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As filed with the Securities and Exchange Commission on June 5, 2009

Registration No. 333-156276

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1 TO

FORM S-3 ON

FORM S-1

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

BIOSANTE PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

111 Barclay Boulevard

Lincolnshire, Illinois 60069

(847) 478-0500

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Phillip B. Donenberg

Chief Financial Officer, Treasurer and Secretary

BioSante Pharmaceuticals, Inc.

111 Barclay Boulevard

Lincolnshire, Illinois  60069

(847) 478-0500

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copy to:

Amy E. Culbert, Esq.

Oppenheimer Wolff & Donnelly LLP

45 South Seventh Street, Suite 3300

Minneapolis, Minnesota  55402

(612) 607-7287

Approximate date of commencement of proposed sale to the public:

From time to time after this registration statement becomes effective.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box:  x

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  o

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Commission, acting pursuant to Section 8(a), may determine.

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The information in this prospectus is not complete and may be changed.  We may not sell these securities until the Securities and Exchange Commission declares our registration statement effective.  This prospectus is not an offer to sell these securities and is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Subject to Completion, dated June 5, 2009

PROSPECTUS

5,705,840 Shares

Common Stock

This prospectus relates to the resale of up to 5,705,840 shares of our common stock by the selling stockholder named herein.  On December 15, 2008, we entered into a common stock purchase agreement with Kingsbridge Capital Limited, or Kingsbridge, pursuant to which we may, in our sole discretion, issue to Kingsbridge up to 5,405,840 shares of our common stock.  On the same date, we also issued Kingsbridge a warrant to purchase up to 300,000 shares of our common stock.  To the extent that we elect to sell any shares of our common stock to Kingsbridge or Kingsbridge elects to exercise the warrant to acquire shares, this prospectus may be used by the selling stockholder named under the section titled “Selling Stockholder” to resell such shares.  We are not selling any securities under this prospectus and will not receive any of the proceeds from the sale of shares by the selling stockholder.

The selling stockholder may sell the shares of common stock described in this prospectus in a number of different ways and at varying prices.  We provide more information about how the selling stockholder may resell its shares of our common stock in the section titled “Plan of Distribution” beginning on page 10.  Kingsbridge is an “underwriter” within the meaning of the Securities Act of 1933 with respect to any shares it resells under this prospectus.  Although we will pay the expenses incurred in registering the shares, we will not be paying any underwriting discounts or commissions in this offering.

Our common stock is listed on the Nasdaq Global Market under the symbol “BPAX.”  On June 4, 2009, the reported closing price of our common stock was $2.32 per share.

Investing in our common stock involves a high degree of risk.  We refer you to “Risk Factors,” beginning on page 8.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete.  Any representation to the contrary is a criminal offense.

The date of this prospectus is                                 , 2009

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In this prospectus, references to “BioSante,” the “company,” “we,” “our” or “us,” unless the context otherwise requires, refer to BioSante Pharmaceuticals, Inc.

We own or have the rights to use various trademarks, trade names or service marks, including BioSante®, Elestrin™, LibiGel®, Bio-T-Gel™, The Pill Plus™, BioVant™, BioLook™, CAP-Oral™ and BioAir™.

You should rely only on the information contained in this prospectus.  We have not authorized any other person to provide you with different information.  This prospectus may only be used where it is legal to sell these securities.  The information in this prospectus is accurate as of the date on the front cover.  You should not assume that the information contained in this prospectus is accurate as of any other date.

This prospectus does not constitute an offer to sell, or a solicitation of an offer to purchase, the securities offered by this prospectus or the solicitation of a proxy, in any jurisdiction to or from any person to whom or from whom it is unlawful to make an offer, solicitation of an offer or proxy solicitation in that jurisdiction.

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PROSPECTUS SUMMARY

The following summary highlights information contained in this prospectus or incorporated by reference into this prospectus. While we have included what we believe to be the most important information about BioSante and this offering, the following summary may not contain all the information that may be important to you. You should read this entire prospectus carefully, including the risks of investing discussed under “Risk Factors” beginning on page 8, and the information to which we refer you and the information incorporated into this prospectus by reference, for a complete understanding of our business and this offering.

Our Company

We are a specialty pharmaceutical company focused on developing products for female sexual health, menopause, contraception and male hypogonadism.  Our primary products are gel formulations of testosterone and estradiol.  We also are engaged in the development of our proprietary calcium phosphate nanotechnology, or CaP, primarily for aesthetic medicine, novel vaccines and drug delivery.

The following is a list of our key products:

·                  LibiGel — once daily transdermal testosterone gel in Phase III clinical development under a Special Protocol Assessment, or SPA, for the treatment of female sexual dysfunction, or FSD.

·                  Elestrin — once daily transdermal estradiol (estrogen) gel approved by the U.S. Food and Drug Administration, or FDA, indicated for the treatment of moderate-to-severe vasomotor symptoms (hot flashes) associated with menopause and marketed in the U.S.

·                  Bio-T-Gel — once daily transdermal testosterone gel in development for the treatment of hypogonadism, or testosterone deficiency, in men.

·                  The Pill-Plus (triple hormone contraceptive) — once daily use of various combinations of estrogens, progestogens and androgens in development for the treatment of FSD in women using oral or transdermal contraceptives.

In order to market our products in the United States, we are required to obtain approval of a new drug application, or NDA, or an abbreviated NDA, or ANDA, for each such product from the FDA.  With respect to Elestrin, we submitted an NDA in February 2006 and received non-conditional and full approval of the NDA from the FDA in December 2006.  In addition, we received three years of marketing exclusivity for Elestrin.  In December 2008, we entered into a sublicense agreement and an asset purchase agreement with Azur Pharma International II Limited for the marketing of Elestrin and the sale of certain assets related to Elestrin.  Azur has agreed to promote Elestrin using its women’s health sales force that targets estrogen prescribing physicians in the U.S. comprised mostly of gynecologists.  In addition, Azur has agreed to minimum marketing expenditures in the first two years of the agreement.

Prior to submitting an NDA or ANDA for our other products, the products must undergo human clinical trials.  With respect to LibiGel, we believe, based on agreements with the FDA, including an SPA received in January 2008, that two Phase III safety and efficacy trials and one year of LibiGel exposure in a Phase III cardiovascular safety study with a four-year follow-up post-NDA filing and potentially post-FDA approval are the essential requirements for submission and, if successful, approval by the FDA of an NDA for LibiGel for the treatment of FSD, specifically, hypoactive sexual desire disorder, or HSDD, in menopausal women.  The SPA process and agreement affirms that the FDA agrees that the LibiGel Phase III safety and efficacy clinical trial design, clinical endpoints, sample size, planned conduct and statistical

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analyses are acceptable to support regulatory approval.  Further, it indicates that these agreed measures will serve as the basis for regulatory review and any decision by the FDA to approve an NDA for LibiGel.  The LibiGel SPA trials use our validated instruments to measure the clinical endpoints.  The January 2008 SPA agreement covers the pivotal Phase III safety and efficacy trials of LibiGel in the treatment of FSD for “surgically” menopausal women.  In July 2008, we received another SPA for our LibiGel program in the treatment of FSD, specifically, HSDD in “naturally” menopausal women.

Currently, three LibiGel Phase III trials are underway: two LibiGel Phase III safety and efficacy clinical trials and one Phase III cardiovascular and breast cancer safety study.  Both Phase III safety and efficacy trials are double-blind, placebo-controlled trials that will enroll up to approximately 500 surgically menopausal women each for a six-month clinical trial.  The Phase III safety study is a randomized, double-blind, placebo-controlled, multi-center, cardiovascular events driven study of between 2,400 and 3,100 women exposed to LibiGel or placebo for 12 months at which time we intend to submit an NDA to the FDA.  Following NDA submission and potential FDA approval, we will continue to follow the subjects in the safety study for an additional four years.  We expect the Phase III clinical trial program of LibiGel to require significant resources.  Therefore, we will need to raise substantial additional capital to fund our operations.  Alternatively, we may choose to sublicense LibiGel, Elestrin (outside the territories already sublicensed) or another product to a third party who may finance a portion or all of the continued development and, if approved, commercialization, sell certain assets or rights we have under our existing license agreements or enter into other business collaborations or combinations, including the possible sale of our company.

Our CaP technology is based on the use of extremely small, solid, uniform particles, which we call “nanoparticles.”  We are pursuing the development of three potential initial applications for our CaP technology. First, CaP technology is being tested in the area of aesthetic medicine.  Second, we are pursuing the creation of improved versions of current vaccines and new vaccines by the “adjuvant” activity of our proprietary nanoparticles that enhance the ability of a vaccine to stimulate an immune response.  The same nanoparticles allow for delivery of the vaccine via alternative routes of administration including non-injectable routes of administration.  Third, we are pursuing the creation of oral, buccal, intranasal, inhaled and longer acting delivery of drugs that currently must be given by injection (e.g., insulin).

The following is a list of our CaP products in development:

·                  BioLook — facial line filler in development using proprietary CaP technology in the area of aesthetic medicine.

·                  BioVant — proprietary CaP adjuvant and delivery technology in development for improved versions of current vaccines and new vaccines against viral and bacterial infections and autoimmune diseases, among others.  BioVant also serves as a delivery system for non-injected delivery of vaccines.

·                  BioOral — a delivery system using CaP technology for oral/buccal/intranasal administration of proteins and other therapies that currently must be injected.

·                  BioAir — a delivery system using CaP technology for inhalable versions of proteins and other therapies that currently must be injected.

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Risks Affecting Us

You should carefully consider the matters discussed in the section “Risk Factors” beginning on page 8, including the following, before you invest in our common stock. For example:

·                  We have a history of operating losses, expect continuing losses and may never become profitable.

·                  We will need to raise substantial additional capital in the near future to fund our operations and we may be unable to raise such funds when needed and on acceptable terms.

·                  One of our strategic goals has been, and continues to be, to seek and implement strategic alternatives with respect to our products and our company, including licenses, business collaborations and other business combinations or transactions with other pharmaceutical and biotechnology companies.  We believe the current domestic and worldwide economic crisis has adversely affected, and may continue to adversely affect, our strategic alternatives process and the results of that process.

·                  Although we believe LibiGel has the potential to be a successful product, its Phase III clinical program requires significant resources and there are significant risks involved in conducting the clinical trials, obtaining regulatory approval and commercializing the product, if approved.

Corporate Information

Our company, which was initially formed as a corporation organized under the laws of the Province of Ontario on August 29, 1996, was continued as a corporation under the laws of the State of Wyoming on December 19, 1996 and was reincorporated under the laws of the State of Delaware on June 26, 2001.

Our principal executive offices are located at 111 Barclay Boulevard, Lincolnshire, Illinois 60069.  Our telephone number is (847) 478-0500 and our Internet web site address is www.biosantepharma.com.  We make available on our website free of charge a link to our annual report on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and amendments to those reports as soon as practicable after we electronically file such material with the Securities and Exchange Commission, or SEC.  Except for the documents specifically incorporated by reference into this prospectus, information contained on our website or that can be accessed through our website does not constitute a part of this prospectus. We have included our website address only as an inactive textual reference and do not intend it to be an active link to our website.

Committed Equity Financing Facility with Kingsbridge

On December 15, 2008, we entered into a committed equity financing facility, or CEFF, with Kingsbridge Capital Limited, pursuant to which Kingsbridge committed to purchase, subject to certain conditions, up to the lesser of $25 million or 5,405,840 shares of our common stock.  In connection with the CEFF, we entered into a common stock purchase agreement and registration rights agreement with Kingsbridge, both dated December 15, 2008, and on that date we also issued a warrant to Kingsbridge to purchase up to 300,000 shares of our common stock at an exercise price of $4.00 per share.  This warrant is exercisable beginning on June 15, 2009 and for a period of five years thereafter.

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The shares of common stock that may be issued to Kingsbridge under the common stock purchase agreement and upon exercise of the warrant will be issued pursuant to an exemption from registration under the Securities Act of 1933, as amended, or the Securities Act.  Pursuant to the registration rights agreement, we have filed a registration statement of which this prospectus is a part, covering the possible resale by Kingsbridge of any shares that we may issue to Kingsbridge under the common stock purchase agreement or upon exercise of the warrant.  Through this prospectus, the selling stockholder may offer to the public for resale shares of our common stock that we may issue to Kingsbridge pursuant to the common stock purchase agreement or that Kingsbridge may acquire upon exercise of the warrant.

The common stock purchase agreement entitles us to sell and obligates Kingsbridge to purchase, from time to time through December 30, 2010 shares of our common stock for cash consideration up to an aggregate of the lesser of $25 million or 5,405,840 shares of our common stock, subject to certain conditions and restrictions.  We are not obligated to sell any shares to Kingsbridge under the common stock purchase agreement.

Through December 30, 2010 we may, from time to time, at our sole discretion, and subject to certain conditions that we must satisfy, “draw down” funds under the CEFF by selling shares of our common stock to Kingsbridge.  The purchase price of these shares will be at a discount ranging from eight to 14 percent of the volume weighted average of the price of our common stock for each of the eight consecutive trading days following our election to sell shares or “draw down” under the CEFF.  The discount on each of these consecutive eight trading days will be determined as follows:

*                 As set forth in the common stock purchase agreement, “VWAP” means the volume weighted average price (the aggregate sales price of all trades of our common stock during each trading day divided by the total number of shares of common stock traded during that trading day) of our common stock during any trading day as reported by Bloomberg L.P. using the AQR function. The VWAP and corresponding discount will be determined for each of the eight trading days during a draw down pricing period.

During the eight trading day pricing period for a draw down, if the VWAP for any trading day is less than the greater of (i) $1.15 or (ii) 90% of the closing price of our common stock for the trading day immediately preceding the beginning of the draw down pricing period, the VWAP for that trading day will not be used in calculating the number of shares to be issued in connection with that draw down, and the draw down amount for that pricing period will be reduced by one-eighth (1/8) of the draw down amount we had initially specified.  In addition, if trading in our common stock is suspended for any reason for more than three consecutive or non-consecutive hours during trading hours on any trading day during a draw down pricing period, that trading day will not be used in calculating the number of shares to be issued in connection with that draw down, and the draw down amount for that pricing period will be reduced by one-eighth (1/8) of the draw down amount we had initially specified.

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The maximum number of shares of common stock that we can issue pursuant to the CEFF is 5,405,840 shares.  An additional 300,000 shares of common stock are issuable if Kingsbridge exercises the warrant that we issued to it in connection with the CEFF.  We intend to exercise our right to draw down amounts under the CEFF, if and to the extent available, at such times as we have a need for additional capital and when we believe that sales of stock under the CEFF provide an appropriate means of raising capital.

Our ability to require Kingsbridge to purchase our common stock is subject to various limitations.  We can make individual draw downs of a maximum amount of, at our discretion, the lesser of (i)(a) 1.5% of our market capitalization as of the date the applicable drawn down notice is given if the market capitalization is equal to or greater than $325 million, (b) 1.0% of our market capitalization as of the date of the applicable drawn down notice is given is such market capitalization is equal to or greater than $180 million but less than $325 million, (c) 0.5% of our market capitalization as of the date of the applicable drawn down notice is given is such market capitalization is equal to or greater than $35 million but less than $180 million or (d) zero if our market capitalization as of the date of the applicable draw down notice is given is less than $35 million and (ii) $5 million.  Unless we and Kingsbridge agree otherwise, a minimum of 15 trading days must elapse between the expiration of any draw down pricing period and the beginning of the next succeeding draw down pricing period. Kingsbridge is not obligated to purchase shares of our common stock when the volume weighted average of the price of our common stock is below $1.15 per share.

During the term of the CEFF, without Kingsbridge’s prior written consent, we may not issue securities that are, or may become, convertible or exchangeable into shares of our common stock where the purchase, conversion or exchange price for our common stock is determined using any floating discount or other post-issuance adjustable discount to the market price of our common stock, including pursuant to an equity line or other financing that is substantially similar to the arrangement provided for in the CEFF, with certain exceptions.

The issuance of our common stock under the CEFF or upon exercise of the Kingsbridge warrant will have no effect on the rights or privileges of existing holders of common stock except that the economic and voting interests of each stockholder will be diluted as a result of any issuance. Although the number of shares of common stock that stockholders presently own will not decrease, these shares will represent a smaller percentage of our total shares that will be outstanding after any issuances of shares of common stock to Kingsbridge.  If we draw down amounts under the CEFF when our share price is decreasing, we will need to issue more shares to raise the same amount than if we were to issue shares when our stock price is higher.  Such issuances will have a dilutive effect and may further decrease our stock price.

Kingsbridge agreed in the common stock purchase agreement that during the term of the CEFF, neither Kingsbridge nor any of its affiliates, nor any entity managed or controlled by it, will enter into, execute, or cause or assist any other person to enter into or execute, any short sale of any of our securities, including our common stock, or engage, through related parties or otherwise, in derivative transactions directly related to shares of our common stock, except during the term of a draw down pricing period with respect to the shares that Kingsbridge purchased pursuant to the CEFF during that draw down pricing period.  Subject to the foregoing restrictions, Kingsbridge has the right during any draw down pricing period to sell shares of our common stock equal in number to the aggregate number of shares of common stock purchased pursuant to the applicable draw down.

Before Kingsbridge is obligated to buy any shares of our common stock pursuant to a draw down, the following conditions, none of which is in the control of Kingsbridge, must be met as of the date we notify Kingsbridge of our election to sell shares pursuant to the CEFF, each trading day during the draw

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down pricing period and the date upon which each settlement of the purchase and sale of our common stock occurs with respect to such draw down:

·                  Each of our representations and warranties in the common stock purchase agreement must be true and correct in all material respects as of the date when made as though made at that time, except for representations and warranties that are expressly made as of a particular date.

·                  We must have performed, satisfied and complied in all material respects with all covenants, agreements and conditions required by the common stock purchase agreement, the registration rights agreement and the warrant to be performed, satisfied or complied with by us.

·                  We must have complied in all respects with all applicable federal, state and local governmental laws, rules, regulations and ordinances in connection with the execution, delivery and performance of the common stock purchase agreement and the consummation of the transactions contemplated by it, except for such failures to comply as would not have a material adverse effect on the business, operations, properties or financial condition of us and our subsidiaries as a whole or prohibit or otherwise interfere with our ability to perform any of our obligations under the common stock purchase agreement, the registration rights agreement or the warrant in any material respect.

·                  The registration statement, of which this prospectus is a part, must have previously become effective and must remain effective and neither us nor Kingsbridge shall have received notice that the SEC has issued or intends to issue a stop order with respect to the registration statement or that the SEC, either temporarily or permanently, intends or has threatened to do so and no other suspension of the use or withdrawal of the effectiveness of the registration statement or this prospectus shall exist.

·                  We must not have knowledge of any event that could reasonably be expected to have the effect of causing the registration statement, of which this prospectus is a part, to be suspended or otherwise ineffective.

·                  Trading in our common stock must not have been suspended by the SEC, the Nasdaq Global Market or the Financial Industry Regulatory Authority and trading in securities generally on the Nasdaq Global Market must not have been suspended or limited.

·                  There must not be any statute, rule, regulation, order, decree, writ, ruling or injunction enacted, entered, promulgated, endorsed or, to our knowledge, threatened by any court or governmental authority which prohibits the consummation of or would materially modify or delay any of the transactions contemplated by the common stock purchase agreement.

·                  There must not be any action, suit or proceeding before any arbitrator or any governmental authority that is pending, and, to our knowledge, there must not be any investigation by any governmental authority threatened, against us or any of our officers, directors or affiliates seeking to enjoin, prevent or change the transactions contemplated by the common stock purchase agreement or seeking material damages in connection with such transactions.

·                  We must have sufficient shares of common stock, calculated using the closing sale price of our common stock as of the trading day immediately preceding the date we notify Kingsbridge of our election to sell shares to Kingsbridge pursuant to the CEFF, registered

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under the registration statement of which this prospectus is a part to issue and sell such shares in accordance with such draw down.

·                  We must not be in default in any material respect under the warrant.

·                  Kingsbridge must have received an opinion of counsel as to certain legal matters regarding the transaction from our outside legal counsel.

There is no guarantee that we will be able to meet the foregoing conditions or that we will be able to draw down any portion of the amounts available under the CEFF.

We also entered into a registration rights agreement with Kingsbridge, dated December 15, 2008.  Pursuant to the registration rights agreement, we have filed the registration statement, of which this prospectus is a part, with the SEC relating to the resale by Kingsbridge of any shares of common stock purchased by it under the common stock purchase agreement or issued to it upon the exercise of its warrant.  The effectiveness of this registration statement is a condition precedent to our ability to sell common stock to Kingsbridge under the common stock purchase agreement.  We are entitled in certain circumstances, including the existence of certain kinds of material nonpublic information, to deliver a “blackout” notice to Kingsbridge to suspend the use of this prospectus and prohibit Kingsbridge from selling shares under this prospectus for a period of not more than 30 days.  If we deliver a blackout notice in the 15 trading days following the settlement of a draw down or if the registration statement, of which this prospectus is a part, is not effective in circumstances not permitted by the registration rights agreement, then we must pay amounts to Kingsbridge or issue Kingsbridge additional shares in lieu of payment.  The payment or issuance would be calculated based on the number of shares held by Kingsbridge that were purchased pursuant to such draw down and the change in the market price of our common stock between the date the blackout notice is delivered (or the registration statement is not effective) and the date the prospectus again becomes available.

We may terminate the CEFF upon one trading day’s notice to Kingsbridge, except that we may not terminate the CEFF during any draw down pricing period.  Kingsbridge may, upon one trading day’s notice to us, terminate the CEFF if we enter into a transaction prohibited by the common stock purchase agreement without Kingsbridge’s prior written consent or if Kingsbridge provides notice to us of a material adverse event relating to our business and the event continues for 10 trading days after the notice.  Kingsbridge may also terminate the CEFF upon one trading day’s notice to us at any time in the event that a registration statement is not initially declared effective in accordance with the registration rights agreement.  In addition, either we or Kingsbridge may terminate the CEFF upon one trading day’s notice if the other party has breached a material representation, warranty or covenant to the common stock purchase agreement and such breach is not remedied within 10 trading days after notice of such breach is delivered to the breaching party. In the event of a termination of the CEFF by Kingsbridge or us pursuant to the terms of the CEFF, Kingsbridge would retain the warrant to purchase 300,000 shares of our common stock.

The foregoing summary of the CEFF does not purport to be complete and is qualified by reference to the common stock purchase agreement, the registration rights agreement and the warrant, copies of which have been filed as exhibits to the registration statement of which this prospectus is a part.

As of June 5, 2009, we had not issued any shares of our common stock to Kingsbridge under the CEFF.

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RISK FACTORS

Investing in our common stock involves a high degree of risk. You should carefully consider the risks and uncertainties set forth under the heading “Risk Factors” in our annual report on Form 10-K for the year ended December 31, 2008, which is incorporated by reference into this prospectus, before you decide to purchase our common stock. If any of these possible adverse events actually occurs, we may be unable to conduct our business as currently planned and our financial condition and operating results could be harmed. In addition, the trading price of our common stock could decline due to the occurrence of any of these risks, and you may lose all or a part of your investment. Please see “Special Note Regarding Forward-Looking Statements” and “Incorporation by Reference.”

CAUTIONARY STATEMENT CONCERNING
FORWARD-LOOKING STATEMENTS

This prospectus and the documents that we have incorporated by reference into this prospectus contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.  All statements other than statements of historical facts included in or incorporated by reference into this prospectus that address activities, events or developments that we expect, believe or anticipate will or may occur in the future are forward-looking statements.  Our forward-looking statements generally include statements about our plans, objectives, strategies and prospects regarding, among other things, our business, results of operations, liquidity and financial condition.  In some cases, we have identified these forward-looking statements with words like “believe,” “may,” “could,” “might,” “possible,” “potential,” “project,” “will,” “should,” “expect,” “intend,” “plan,” “predict,” “anticipate,” “estimate,” “approximate,” “contemplate” or “continue” or the negative of these words or other words and terms of similar meaning.

Forward-looking statements involve risks and uncertainties.  These uncertainties include factors that affect all businesses as well as matters specific to us.  Some of the factors known to us that could cause our actual results to differ materially from what we have anticipated in our forward-looking statements include:  our ability to implement strategic alternatives with respect to our products and our company, including licenses, business collaborations, and other business combinations or transactions with other pharmaceutical and biotechnology companies; our ability to obtain additional capital when needed or on acceptable terms; the effects of the current global economic crisis and our ability to seek strategic alternatives or raise additional capital or otherwise conduct our business in light thereof; the level of market acceptance of Elestrin, and our other products if and when they are commercialized; our dependence upon our licensees for the development, marketing and sale of certain of our products, including in particular Azur to sell Elestrin; our dependence upon the maintenance of our licenses with Antares Pharma IPL AG, Wake Forest University Health Sciences and Cedars-Sinai Medical Center and the University of California — Los Angeles; subject recruitment and enrollment in our current and future clinical trials, including in particular our Phase III clinical trial program for LibiGel; uncertainties associated with the impact of published studies regarding the adverse health effects of certain forms of hormone therapy; the failure of certain of our products to be commercially introduced for several years or at all; our failure to obtain and maintain required regulatory approvals on a timely basis or at all; our ability to compete in a competitive industry; our ability to protect our proprietary technology and to operate our business without infringing the proprietary rights of third parties; our dependence upon key employees; our ability to maintain effective internal controls over financial reporting; adverse changes in applicable laws or regulations and our failure to comply with applicable laws and regulations; changes in generally accepted accounting principles; or conditions and changes in the biopharmaceutical industry or in general economic or business conditions.  We refer you to the section entitled “Risk Factors” in our annual report on Form 10-K for the year ended December 31, 2008, which is incorporated by reference into this prospectus, and in any similar section in any accompanying prospectus supplement.

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We wish to caution readers not to place undue reliance on any forward-looking statement that speaks only as of the date made and to recognize that forward-looking statements are predictions of future results, which may not occur as anticipated.  Actual results could differ materially from those anticipated in the forward-looking statements and from historical results, due to the risks and uncertainties described above and under the section entitled “Risk Factors” in our annual report on Form 10-K for the year ended December 31, 2008, which is incorporated by reference into this prospectus, and in any similar section in any accompanying prospectus supplement, as well as others that we may consider immaterial or do not anticipate at this time.  Although we believe that the expectations reflected in our forward-looking statements are reasonable, we do not know whether our expectations will prove correct.  We assume no obligation to update forward-looking statements to reflect actual results or changes in factors or assumptions affecting such forward-looking statements, except if we otherwise are required by law.  We advise you, however, to consult any further disclosures we make on related subjects in our annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K we file with or furnish to the Securities and Exchange Commission.

USE OF PROCEEDS

We will not receive any of the proceeds from the sale of shares of our common stock by the selling stockholder pursuant to this prospectus. Any issuance of shares by us to Kingsbridge under the common stock purchase agreement or in connection with the exercise of the Kingsbridge warrant will be made pursuant to an exemption from the registration requirements of the Securities Act. To the extent the warrant held by the selling stockholder is exercised at its current exercise price, we would receive approximately $1.2 million in cash proceeds, unless such warrant is exercised on a cashless basis pursuant to its terms.

We currently intend to use the proceeds from our sales, if any, to Kingsbridge to finance our Phase III clinical trials for LibiGel and for working capital and other general corporate purposes.  We may also use a portion of the proceeds to acquire or invest in complementary businesses or products or to obtain rights to additional product candidates and other technologies. We have no commitments with respect to any such acquisitions or investments.  The amounts and timing of our actual expenditures will depend on numerous factors, including the progress in, and costs of, our Phase III clinical trials for LibiGel, the timing of revenues, if any, from any future collaborations or similar transactions and the amount of cash used by our operations.  We therefore cannot estimate the amount of proceeds to be used for all of the purposes described above.  We may find it necessary or advisable to use the net proceeds for other purposes, and we will have broad discretion in the application of the proceeds.  Pending the uses described above, we intend to deposit the proceeds temporarily in our non-interest bearing 100% FDIC-insured checking account or to invest them temporarily in short-term or marketable securities until we use them for their stated purpose.

SELLING STOCKHOLDER

This prospectus relates to the possible resale by the selling stockholder, Kingsbridge, of shares of common stock that we may issue pursuant to the common stock purchase agreement we entered into with Kingsbridge in December 2008, or upon exercise of the warrant that we issued to Kingsbridge in December 2008.  We are filing the registration statement, of which this prospectus is a part, pursuant to the provisions of the registration rights agreement we entered into with Kingsbridge.  The selling stockholder may from time to time offer and sell pursuant to this prospectus any or all of the shares that it acquires under the common stock purchase agreement or upon exercise of the warrant.

The following table presents information regarding Kingsbridge, as the selling stockholder, and the shares that it may offer and sell from time to time under this prospectus.  This table is prepared based

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on information supplied to us by the selling stockholder, and reflects holdings as of May 26, 2009.  As used in this prospectus, the term “selling stockholder” includes Kingsbridge and any donees, pledges, transferees or other successors in interest selling shares received after the date of this prospectus from the selling stockholder as a gift, pledge, or other non-sale related transfer.  The number of shares in the column “Number of Shares Being Offered” represents all of the shares that the selling stockholder may offer under this prospectus.  The selling stockholder may sell some, all or none of its shares.  We do not know how long the selling stockholder will hold the shares before selling them, and we currently have no agreements, arrangements or understandings with the selling stockholder regarding the sale of any of the shares.

Beneficial ownership is determined in accordance with Rule 13d-3(d) promulgated by the SEC under the Securities Exchange Act of 1934, as amended.  The percentage of shares of common stock beneficially owned prior to the offering shown in the table below is based both on an aggregate of 27,042,764 shares of our common stock outstanding on May 26, 2009, and on the assumption that all shares of common stock issuable under the common stock purchase agreement with Kingsbridge and all shares of common stock issuable upon exercise of the warrant are outstanding as of that date.

*              Less than one percent (1%)

PLAN OF DISTRIBUTION

To the extent that we issue shares to Kingsbridge under the CEFF or Kingsbridge acquires shares upon exercise of its warrant, the selling stockholder may offer such shares for resale under this prospectus. Except as described below, to our knowledge, the selling stockholder has not entered into any agreement, arrangement or understanding with any particular broker or market maker with respect to the shares of common stock offered hereby, nor, except as described below, do we know the identity of the brokers or market makers that will participate in the resale of the shares.

The selling stockholder may decide not to sell any shares.  The selling stockholder may from time to time offer some or all of the shares of common stock through brokers, dealers or agents who may receive compensation in the form of discounts, concessions or commissions from the selling stockholder and/or the purchasers of the shares of common stock for whom they may act as agent.  In effecting sales,

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broker-dealers that are engaged by the selling stockholder may arrange for other broker-dealers to participate. Kingsbridge is an “underwriter” within the meaning of the Securities Act.  Any brokers, dealers or agents who participate in the distribution of the shares of common stock by the selling stockholder may also be deemed to be “underwriters,” and any profits on the sale of the shares of common stock by them and any discounts, commissions or concessions received by any such brokers, dealers or agents may be deemed to be underwriting discounts and commissions under the Securities Act.  To the extent the selling stockholder may be deemed to be an underwriter, the selling stockholder will be subject to the prospectus delivery requirements of the Securities Act and may be subject to certain statutory liabilities of, including but not limited to, Sections 11, 12 and 17 of the Securities Act and Rule 10b-5 under the Securities Exchange Act of 1934, as amended, or the Exchange Act.

The selling stockholder will act independently of us in making decisions with respect to the timing, manner and size of each sale by it.  Such sales may be made on the Nasdaq Global Market, on the over-the-counter market, otherwise, or in a combination of such methods of sale, at then prevailing market prices, at prices related to prevailing market prices or at negotiated prices.  The shares of common stock may be sold by the selling stockholder according to one or more of the following methods:

·                  a block trade in which the broker or dealer so engaged will attempt to sell the shares of common stock as agent but may position and resell a portion of the block as principal to facilitate the transaction;

·                  purchases by a broker or dealer as principal and resale by such broker or dealer for its account pursuant to this prospectus;

·                  an over-the-counter distribution in accordance with the rules of the Nasdaq Stock Market;

·                  ordinary brokerage transactions and transactions in which the broker solicits purchasers;

·                  privately negotiated transactions;

·                  a combination of such methods of sale; and

·                  any other method permitted pursuant to applicable law.

Any shares covered by this prospectus which qualify for sale pursuant to Rule 144 of the Securities Act may be sold under Rule 144 rather than pursuant to this prospectus.  In addition, the selling stockholder may transfer the shares by other means not described in this prospectus.

Any broker-dealer participating in such transactions as agent may receive commissions from Kingsbridge (and, if they act as agent for the purchaser of such shares, from such purchaser).  Broker-dealers may agree with Kingsbridge to sell a specified number of shares at a stipulated price per share, and, to the extent such a broker-dealer is unable to do so acting as agent for Kingsbridge, to purchase as principal any unsold shares at the price required to fulfill the broker-dealer commitment to Kingsbridge.  Broker-dealers who acquire shares as principal may thereafter resell such shares from time to time in transactions (which may involve crosses and block transactions and which may involve sales to and through other broker-dealers, including transactions of the nature described above) on the Nasdaq Global Market, on the over-the-counter market, in privately-negotiated transactions or otherwise at market prices prevailing at the time of sale or at negotiated prices, and in connection with such resales may pay to or receive from the purchasers of such shares commissions computed as described above.  To the extent required under the Securities Act, an amendment to this prospectus or a prospectus supplement will be filed, disclosing:

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·                  the name of any such broker-dealers;

·                  the number of shares involved;

·                  the price at which such shares are to be sold;

·                  the commission paid or discounts or concessions allowed to such broker-dealers, where applicable;

·                  that such broker-dealers did not conduct any investigation to verify the information set out or incorporated by reference in this prospectus, as supplemented; and

·                  other facts material to the transaction.

Underwriters and purchasers that are deemed underwriters under the Securities Act may engage in transactions that stabilize, maintain or otherwise affect the price of the securities, including the entry of stabilizing bids or syndicate covering transactions or the imposition of penalty bids.  Kingsbridge and any other persons participating in the sale or distribution of the shares will be subject to the applicable provisions of the Exchange Act and the rules and regulations thereunder including, without limitation, Regulation M.  These provisions may restrict certain activities of, and limit the timing of, purchases by the selling stockholder or other persons or entities.  Under Regulation M, persons engaged in a distribution of securities are prohibited from simultaneously engaging in market making and certain other activities with respect to such securities for a specified period of time prior to the commencement of such distributions, subject to special exceptions or exemptions.  Regulation M may restrict the ability of any person engaged in the distribution of the securities to engage in market-making and certain other activities with respect to those securities.  The anti-manipulation rules under the Exchange Act may apply to sales of the securities in the market.  All of these limitations may affect the marketability of the shares and the ability of any person to engage in market-making activities with respect to the securities.

We have agreed to pay the expenses of registering the shares of common stock under the Securities Act, including registration and filing fees, printing expenses, administrative expenses and certain legal and accounting fees, as well as certain fees of counsel for the selling stockholder incurred in the preparation and negotiation of the CEFF agreements and the registration statement of which this prospectus forms a part.  The selling stockholder will bear all discounts, commissions or other amounts payable to underwriters, dealers or agents, as well as transfer taxes and certain other expenses associated with its sale of securities.

Under the terms of the Kingsbridge common stock purchase agreement and the registration rights agreement, we have agreed to indemnify the selling stockholder and certain other persons against certain liabilities in connection with the offering of the shares of common stock offered hereby, including liabilities arising under the Securities Act or, if such indemnity is unavailable, to contribute toward amounts required to be paid in respect of such liabilities.

At any time a particular offer of the shares of common stock is made by the selling stockholder, a revised prospectus or prospectus supplement, if required, will be distributed.  Such prospectus supplement or post-effective amendment will be filed with the SEC, to reflect the disclosure of required additional information with respect to the distribution of the shares of common stock.  We may suspend the sale of shares by the selling stockholder pursuant to this prospectus for certain periods of time for certain reasons, including if the prospectus is required to be supplemented or amended to include additional material information.

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DESCRIPTION OF CAPITAL STOCK

The following description of our capital stock is only a summary.  You should refer to our certificate of incorporation and bylaws, both of which have been filed with the SEC as exhibits to our registration statement of which this prospectus is a part. See “Where You Can Find More Information.”

Authorized and Outstanding Capital Stock

We are authorized to issue 100,000,000 shares of common stock, $0.0001 par value per share, 4,687,684 shares of class C special stock, $0.0001 par value per share, and 10,000,000 shares of undesignated preferred stock, $0.0001 par value per share.  As of May 26, 2009, we had 27,042,764 shares of common stock outstanding, 391,286 shares of class C special stock outstanding and no shares of preferred stock outstanding.

Common Stock

For all matters submitted to a vote of stockholders, each holder of common stock is entitled to one vote for each share registered in the holder’s name on our books. Our common stock does not have cumulative voting rights.  The holders of a majority of the shares of our common stock and class C special stock entitled to vote in any election of directors, voting together as a single class, can elect all of the directors standing for election, if they so choose.  Subject to limitations under Delaware law and preferences that may be applicable to any then outstanding preferred stock, holders of common stock are entitled to receive ratably those dividends, if any, as may be declared by our board of directors out of legally available funds.  Upon our liquidation, dissolution or winding up, the holders of common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all of our debts and other liabilities of our company, subject to the prior rights of any preferred stock then outstanding.  All shares of our outstanding common stock are fully paid and nonassessable and any additional shares of common stock that we issue will be fully paid and nonassessable.  Holders of our common stock do not have preemptive or subscription rights, and they have no right to convert their common stock into any other securities. There are no redemption or sinking fund provisions applicable to the common stock.  The rights, preferences and privileges of common stockholders are subject to the rights of the stockholders of any series of preferred stock which we may designate in the future. Our certificate of incorporation and bylaws do not restrict the ability of a holder of common stock to transfer the holder’s shares of common stock.

Class C Special Stock

Each share of class C special stock entitles its holder to one vote per share. Each share of our class C special stock is exchangeable, at the option of the holder, for one share of common stock, at an exchange price of $2.50 per share, subject to adjustment upon certain capitalization events. Holders of our class C special stock are not entitled to receive dividends. Holders of our class C special stock are not entitled to participate in the distribution of our assets upon any liquidation, dissolution or winding-up of our company. The holders of our class C special stock have no cumulative voting, preemptive, subscription, redemption or sinking fund rights.

Preferred Stock

The board of directors is authorized, without stockholder approval subject to any limitations prescribed by law and imposed by the listing standards of the Nasdaq Global Market, to issue up to an aggregate of 10,000,000 shares of preferred stock in one or more series and to fix the rights, preferences, privileges and restrictions granted to or imposed upon the preferred stock, including voting rights,

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dividend rights, conversion rights, redemption privileges and liquidation preferences. The rights of the holders of our common stock and class C special stock will be subject to, and may be adversely affected by, the rights of holders of any preferred stock that may be issued in the future. Our board of directors could authorize the issuance of shares of preferred stock with terms and conditions more favorable than our common stock or class C special stock and with rights that could adversely affect the voting power or other rights of holders of our common stock or class C special stock.  Prior to issuance of shares of each series of our undesignated preferred stock, our board of directors is required by the Delaware General Corporate Law and our certificate of incorporation to adopt resolutions and file a Certificate of Designations with the Secretary of State of the State of Delaware, fixing for each such series the designations, powers, preferences, rights, qualifications, limitations and restrictions of the shares of such series.  Issuance of preferred stock, while providing flexibility in connection with possible acquisitions and other corporate purposes, could have the effect of delaying, deferring or preventing a change in control of our company.  We have no present plans to issue any shares of preferred stock.

Stock Options

As of May 26, 2009, we had an aggregate of 2,736,691shares of common stock reserved for issuance upon the exercise of outstanding stock options granted under the BioSante Pharmaceuticals, Inc. Amended and Restated 1998 Stock Plan and the BioSante Pharmaceuticals, Inc. 2008 Stock Incentive Plan and an additional 1,098,500 shares of common stock reserved for issuance pursuant to future grants under the BioSante Pharmaceuticals, Inc. 2008 Stock Incentive Plan.

Warrants

As of May 26, 2009, we had an aggregate of 2,698,705 shares of common stock reserved for issuance upon the exercise of outstanding warrants.  As of May 26, 2009, the following warrants were outstanding:

·                  Warrants to purchase an aggregate of 534,996 shares of our common stock at an exercise price of $7.00 per share issued to various institutional and accredited investors in connection with our private placement completed on May 14, 2004;

·                  Warrants to purchase an aggregate of 853,292 shares of our common stock at an exercise price of $2.75 per share issued to various institutional and accredited investors in connection with our private placement completed on July 21, 2006;

·                  Warrants to purchase an aggregate of 763,750 shares of our common stock at an exercise price of $8.00 per share issued to various institutional and accredited investors in connection with our private placement completed on June 13, 2007;

·                  A warrant to purchase up to 300,000 shares of our common stock at an exercise price of $4.00 per share issued to Kingsbridge Capital Limited on December 15, 2008 connection with our committed equity financing facility; and

·                  Warrants to purchase an aggregate of 246,667 shares of our common stock at exercise prices ranging from $4.78 to $8.00 issued to investor and public relations vendors in 2007 and 2008.

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Anti-Takeover Effects of Provisions of Our Certificate of Incorporation, Our Bylaws and Delaware Law

Some provisions of our certificate of incorporation and bylaws and Delaware law contain provisions that could make the following transactions more difficult: acquisition of us by means of a tender offer; acquisition of us by means of a proxy contest or otherwise; or removal of our incumbent officers and directors. It is possible that these provisions could make it more difficult to accomplish or could deter transactions that stockholders may otherwise consider to be in their best interest or in our best interests, including transactions that might result in a premium over the market price for our shares.

These provisions, summarized below, are designed to discourage coercive takeover practices and inadequate takeover bids. These provisions also are designed to encourage persons seeking to acquire control of us to first negotiate with our board of directors. We believe that the benefits of increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure us outweigh the disadvantages of discouraging these proposals because negotiation of these proposals could result in an improvement of their terms.

Certificate of Incorporation and Bylaws

The following provisions in our certificate of incorporation and bylaws could delay or discourage transactions involving an actual or potential change in control or change in our management, including transactions that stockholders may otherwise consider to be in their best interest or in our best interests, including transactions that might result in a premium over the market price for our shares.

·                  Authorized But Unissued Capital Stock.  We have shares of common stock, class C special stock and undesignated preferred stock available for future issuance without stockholder approval, subject to any limitations imposed by the listing standards of the Nasdaq Global Market. We may use these additional shares for a variety of corporate purposes, including for future public offerings to raise additional capital or to facilitate corporate acquisitions or for payment as a dividend on our capital stock.  The existence of unissued and unreserved capital stock may enable our board of directors to issue shares to persons friendly to current management that could render more difficult or discourage a third-party attempt to obtain control of us by means of a merger, tender offer, proxy contest or otherwise, thereby protecting the continuity of our management.  In addition, the ability to authorize undesignated preferred stock makes it possible for our board of directors to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to change control of us. These and other provisions may have the effect of deferring hostile takeovers or delaying changes in control or management of our company.

·                  Stockholder Meetings.  Our bylaws provide that a special meeting of stockholders may be called only by our chairman of the board, president and chief executive officer, or by our board of directors.

·                  Requirements for Advance Notification of Stockholder Nominations and Proposals.  Our bylaws establish advance notice procedures with respect to stockholder proposals and the nomination of candidates for election as directors, other than nominations made by or at the direction of the board of directors or a committee of the board of directors.

·                  No Cumulative Voting Rights.  Our certificate of incorporation and bylaws do not provide for cumulative voting rights. The holders of a majority of the shares of our common stock and

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class C special stock entitled to vote in any election of directors, voting together as a single class, can elect all of the directors standing for election, if they so choose.

Delaware Anti-Takeover Law

We are subject to Section 203 of the Delaware General Corporation Law. This law prohibits a publicly-held Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years following the date that the stockholder became an interested stockholder unless:

·                  prior to the date of the transaction, the board of directors of the corporation approved either the business combination or the transaction which resulted in the stockholder becoming an interested stockholder;

·                  upon consummation of the transaction which resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the number of shares outstanding those shares owned by persons who are directors and also officers and by employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or

·                  on or subsequent to the date of the transaction, the business combination is approved by the board of directors and authorized at an annual or special meeting of stockholders, and not by written consent, by the affirmative vote of at least two-thirds of the outstanding voting stock which is not owned by the interested stockholder.

Section 203 defines “business combination” to include:

·                  any merger or consolidation involving the corporation and the interested stockholder;

·                  any sale, transfer, pledge or other disposition of 10% or more of our assets involving the interested stockholder;

·                  in general, any transaction that results in the issuance or transfer by us of any of our stock to the interested stockholder; or

·                  the receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other financial benefits provided by or through the corporation.

Listing for our Common Stock

Our common stock is listed on the Nasdaq Global Market under the symbol “BPAX.”

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Computershare Investor Services, LLC.

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LEGAL MATTERS

The validity of the shares of common stock offered hereby has been passed upon for BioSante by Oppenheimer Wolff & Donnelly LLP, Minneapolis, Minnesota.

EXPERTS

The financial statements incorporated in this prospectus by reference from the BioSante Pharmaceuticals, Inc.’s Annual Report on Form 10-K, and the effectiveness of BioSante’s internal control over financial reporting have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their reports, which are incorporated herein by reference.  Such financial statements have been so incorporated in reliance upon the reports of such firm given upon their authority as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We are a public company and file annual, quarterly and current reports, proxy statements and other information with the Securities and Exchange Commission.  You may read and copy any document we file at the SEC’s Public Reference Room at 100 F Street, N.E., Room 1580, Washington, D.C. 20549.  You can request copies of these documents by writing to the SEC and paying a fee for the copying cost.  Please call the SEC at 1-800-SEC-0330 for more information about the operation of the public reference room. Our SEC filings are also available to the public at the SEC’s web site at http://www.sec.gov.

Our common stock is listed on the Nasdaq Global Market.  Reports and other information concerning BioSante may also be inspected at the offices of the Nasdaq OMX Group, Inc., 9600 Blackwell Road, Rockville, MD  20850 or on the Nasdaq OMX Group, Inc. website at http://www.nasdaq.com.

We also file annual audited and interim unaudited financial statements, proxy statements and other information with the Ontario, Alberta and British Columbia Securities Commissions.  Copies of these documents that are filed through the System for Electronic Document Analysis and Retrieval “SEDAR” of the Canadian Securities Administrators are available at its web site http://www.sedar.com.

In addition, we maintain a web site that contains information regarding our company, including copies of reports, proxy statements and other information we file with the SEC.  The address of our web site is www.biosantepharma.com.  Except for the documents specifically incorporated by reference into this prospectus, information contained on our website or that can be accessed through our website does not constitute a part of this prospectus. We have included our website address only as an inactive textual reference and do not intend it to be an active link to our website.

We have filed a registration statement on Form S-1 with the SEC for the common stock offered by the selling stockholder under this prospectus.  This prospectus does not include all of the information contained in the registration statement.  You should refer to the registration statement and its exhibits for additional information that is not contained in this prospectus.  Whenever we make reference in this prospectus to any of our contracts, agreements or other documents, you should refer to the exhibits attached to the registration statement for copies of the actual contract, agreement or other document.  You may:

·                  inspect a copy of this prospectus, including the exhibits and schedules, without charge at the public reference room;

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·                  obtain a copy from the SEC upon payment of the fees prescribed by the SEC; or

·                  obtain a copy from the SEC website.

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate by reference” information into this prospectus.  This means that we can disclose important information to you by referring you to those documents.  Any information referred to in this way is and thus incorporated by reference is considered to be part of this prospectus.  We incorporate by reference into this prospectus the following documents or information filed with the SEC (other than, in each case, documents or information deemed to have been furnished and not filed in accordance with SEC rules):

·                  our annual report on Form 10-K for the year ended December 31, 2008;

·                  our definitive proxy statement in connection with our 2009 annual meeting of stockholders;

·                  our quarterly report on Form 10-Q for the quarter ended March 31, 2009; and

·                  the description of our common stock contained in our registration statement on Form 8-A/A filed on October 31, 2007 and any amendments or reports filed for the purpose of updating such description.

We will provide without charge to each person, including any beneficial owner, to whom this prospectus is delivered, upon his or her written or oral request, a copy of any or all of the reports or documents referred to above that have been incorporated by reference into this prospectus excluding exhibits to those documents unless they are specifically incorporated by reference into those documents. You can request those documents by contacting our Phillip B. Donenberg, Chief Financial Officer, Treasurer and Secretary, BioSante Pharmaceuticals, Inc., 111 Barclay Boulevard, Lincolnshire, Illinois  60069, by telephone at (847) 478-0500 ext. 101 or by email at pdonenberg@biosantepharma.com, or you may obtain them from our corporate website at www.biosantepharma.com.  Except for the documents specifically incorporated by reference into this prospectus, information contained on our website or that can be accessed through our website does not constitute a part of this prospectus. We have included our website address only as an inactive textual reference and do not intend it to be an active link to our website.

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PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 13.  Other Expenses of Issuance and Distribution.

The following table sets forth the costs and expenses payable by BioSante in connection with the issuance and distribution of the shares of common stock being registered.  The selling stockholder will not bear any portion of such expenses.  All such expenses are estimated except for the SEC registration fee.

*                                         None of the expenses listed above will be borne by the selling stockholder.

Item 14.  Indemnification of Directors and Officers.

BioSante’s Certificate of Incorporation limits the liability of its directors to the fullest extent permitted by the Delaware General Corporation Law.  Specifically, Article VII of BioSante’s Certificate of Incorporation provides that no director of BioSante shall be personally liable to BioSante or its stockholders for monetary damages for any breach of fiduciary duty by such a director as a director, except to the extent provided by applicable law (i) for any breach of the director’s duty of loyalty to BioSante or its stockholders, (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) pursuant to Section 174 of the Delaware General Corporation Law, or (iv) for any transaction from which such director derived an improper personal benefit.  If the Delaware General Corporation Law is amended to authorize corporate action further eliminating or limiting the personal liability of directors, then the liability of a director of BioSante shall be eliminated or limited to the fullest extent permitted by the Delaware General Corporation Law as so amended.  No amendment to or repeal of Article VII shall apply to or have any effect on the liability or alleged liability of any director of BioSante for or with respect to any acts or omissions of such director occurring prior to such amendment or repeal.

BioSante’s Certificate of Incorporation provides for indemnification of BioSante’s directors and officers. Specifically, Article VI provides that BioSante shall indemnify, to the fullest extent authorized or permitted by law, as the same exists or may thereafter be amended, any person who was or is made or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of BioSante), by reason of the fact that such person is or was a director or officer of BioSante, or is or was serving at the request of BioSante as a director, officer, employee or agent of any other company, partnership, limited liability company, joint venture, trust, employee benefit plan or other enterprise; provided, however, that BioSante shall not indemnify any director or officer in connection with any action by such director or officer against BioSante unless BioSante shall have consented to such action.  BioSante may, to the extent authorized from time to time by BioSante’s Board of Directors, provide rights to indemnification to employees and agents of BioSante similar to those conferred in Article VI to directors and officers of

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BioSante.  No amendment or repeal of Article VI shall apply to or have any effect on any right to indemnification provided thereunder with respect to any acts or omission occurring prior to such amendment or repeal.

BioSante has entered into agreements with its directors and officers regarding indemnification, in addition to indemnification provided for in BioSante’s Certificate of Incorporation, Bylaws and the Delaware General Corporation Law and intends to enter into indemnification agreements with any new directors and officers in the future.  Under these agreements, BioSante is required to indemnify its current and former directors and officers against expenses, judgments, penalties, fines, settlements and other amounts actually and reasonably incurred, including expenses of a derivative action, in connection with an actual or threatened proceeding if any of them may be made a party because he or she is or was one of BioSante’s directors or officers.  BioSante will be obligated to pay these amounts only if the director or officer acted in good faith and in a manner that he or she reasonably believed to be in or not opposed to BioSante’s best interests.  With respect to any criminal proceeding, BioSante will be obligated to pay these amounts only if the director or officer had no reasonable cause to believe his or her conduct was unlawful.  The indemnification agreements also set forth procedures that will apply in the event of a claim for indemnification.

BioSante maintains an insurance policy for its directors and officers pursuant to which its directors and officers are insured against liability for certain actions in their capacity as directors and officers of BioSante.

BioSante has also agreed to indemnify the selling stockholder against certain losses, claims, damages, liabilities, costs and expenses under the securities laws, or to contribute to any losses associated with these liabilities.  The selling stockholder has also agreed to indemnify BioSante against certain civil liabilities under the securities laws deriving from information provided by it, or to contribute to any losses associated with these liabilities.

Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to BioSante’s directors, officers or persons controlling BioSante pursuant to the foregoing provisions, BioSante is aware that in the opinion of the Securities and Exchange Commission that this indemnification is against public policy as expressed in the Securities Act of 1933 and is therefore unenforceable.

Item 15.  Recent Sales of Unregistered Securities.

Since May 26, 2006, we have issued the following securities without registration under the Securities Act:

1.             On December 15, 2008, we entered into a Committed Equity Financing Facility, or CEFF, with Kingsbridge Capital Limited, pursuant to which Kingsbridge has committed to provide up to $25 million of capital through December 30, 2010 through the purchase of newly-issued shares of our common stock.  The terms of the CEFF are set forth in a Common Stock Purchase Agreement and a Registration Rights Agreement, each of which was entered into with Kingsbridge on December 15, 2008.  Under the terms of the CEFF, the maximum number of shares that we may sell is 5,680,840 shares (exclusive of the 300,000 shares underlying a warrant issued concurrently to Kingsbridge with the CEFF).  Subject to certain conditions and limitations, from time to time under the Purchase Agreement, we may, at our sole discretion, require Kingsbridge to purchase newly-issued shares of our common stock in tranches of up to a maximum amount of the lesser of (i) (a) 1.5% of our market capitalization if our market capitalization at the time of the draw down of such tranche is at least $325 million, (b) 1.0% of our market capitalization if our market capitalization at the time of the draw down of such tranche is at least

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$180 million and less than $325 million, or (c) 0.5% of our market capitalization if our market capitalization at the time of the draw down of such tranche is at least $35 million and less than $180 million and (ii) $5 million.  Each tranche will be issued and priced over an eight-day pricing period. Kingsbridge will purchase shares of common stock pursuant to the CEFF at discounts ranging from 8% to 14% depending on the volume-weighted average price of our common stock during the eight-day pricing period, provided that the minimum acceptable purchase price for any shares to be issued to Kingsbridge during the eight-day period will be equal to the higher of $1.15 or 90% of our common stock closing sale price the day before the commencement of each draw down.  In connection with the CEFF, we issued a warrant to Kingsbridge to purchase up to 300,000 shares of common stock at an exercise price of $4.00 per share.  The warrant will become exercisable after the six-month anniversary of the date of the Purchase Agreement, and will remain exercisable, subject to certain exceptions, for a period of five years thereafter.

2.             In May 2008, we issued warrants to purchase an aggregate of 80,000 shares of our common stock at an exercise price of $4.78 to investor and public relations vendors.

3.             In June 2007, we issued warrants to purchase an aggregate of 180,000 shares of our common stock at an exercise price of $8.00 to investor and public relations vendors.

4.             On May 25, 2007, we entered into definitive subscription agreements with certain institutional and other accredited investors, as defined in Rule 501 of Regulation D promulgated under the Securities Act of 1933, as amended, pursuant to which we sold in a private placement an aggregate of 3,054,999 shares of our common stock and warrants to purchase an aggregate of 763,750 shares of our common stock, at a purchase price of $6.00 per unit, for an aggregate purchase price of approximately $18.3 million, resulting in net proceeds to us of approximately $17.3 million, after the deduction of placement agent commissions and estimated offering expenses.  The warrants are exercisable for a period of three years, beginning six months and one day from the date of issuance, at an exercise price of $8.00 per share.

5.             On July 7, 2006, we entered into definitive subscription agreements with certain institutional and other accredited investors, as defined in Rule 501 of Regulation D promulgated under the Securities Act of 1933, as amended, pursuant to which we sold in a private placement an aggregate of 3,812,978 shares of our common stock and warrants to purchase an aggregate of 1,334,542 shares of our common stock, at a purchase price of $2.00 per unit, for an aggregate purchase price of approximately $7.6 million, resulting in net proceeds to us of approximately $7.2 million, after the deduction of placement agent commissions and estimated offering expenses.  The warrants are exercisable for a period of four years and nine months, beginning six months and one day from the date of issuance, at an exercise price of $2.75 per share.

No underwriting commissions or discounts were paid with respect to the sales of the unregistered securities described above. In addition, all of the above sales were made in reliance on either Section 4(2) of the Securities Act as transactions by an issuer not involving any public offering or Regulation D of the Securities Act. In all such transactions, certain inquiries were made by us to establish that such sales qualified for such exemption from the registration requirements. In particular, we confirmed that with respect to the exemption claimed under Section 4(2) of the Securities Act (i) all offers of sales and sales were made by personal contact from officers and directors of BioSante or other persons closely associated with BioSante, (ii) each investor made representations that he or she was sophisticated in relation to this investment (and we have no reason to believe that such representations were incorrect), (iii) each purchaser gave assurance of investment intent and the certificates for the shares bear a legend accordingly, and (iv) offers and sales within any offering were made to a limited number of persons.

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Item 16.  Exhibits and Financial Statement Schedules.

See the Exhibit Index attached to this registration statement that is incorporated herein by reference.

Item 17.  Undertakings.

(a)                                  The undersigned registrant hereby undertakes:

(1)                                 To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i)                                   To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

(ii)                                To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement.  Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement;

(iii)                             To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement.

(2)                                 That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3)                                 To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(b)                                 Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the provisions described above, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable.  In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant has duly caused this amendment to this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Lincolnshire, State of Illinois on June 5, 2009.

Pursuant to the requirements of the Securities Act of 1933, this amendment has been signed by the following persons in the capacities indicated, on the dates indicated.

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BIOSANTE PHARMACEUTICALS, INC.
POST-EFFECTIVE AMENDMENT TO REGISTRATION STATEMENT ON FORM S-1
EXHIBIT INDEX

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(1)           Confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934, as amended, has been granted with respect to designated portions of this document.

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in this Form S-1 (Post-Effective Amendment No. 1 to Registration Statement No. 333-156276 to Form S-3 on Form S-1) of our reports dated March 16, 2009, relating to the financial statements of BioSante Pharmaceuticals, Inc., and the effectiveness of BioSante Pharmaceuticals, Inc.’s internal control over financial reporting, appearing in the Annual Report on Form 10-K of BioSante Pharmaceuticals, Inc. for the year ended December 31, 2008 and to the reference to us under the heading “Experts” in the Prospectus, which is part of such Registration Statement.

/s/ DELOITTE & TOUCHE LLP

Chicago, Illinois

May 29, 2009