2 AMYLIN PHARMACEUTICALS, INC.

Exhibit 4.5

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (55 WATER STREET, NEW YORK, NEW YORK) (THE “DEPOSITARY”, WHICH TERM INCLUDES ANY SUCCESSOR DEPOSITARY FOR THE CERTIFICATES) TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY (AND ANY PAYMENT HEREIN IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

THE NOTE EVIDENCED HEREBY HAS NOT BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), OR ANY STATE SECURITIES LAWS AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT AS SET FORTH IN THE FOLLOWING SENTENCE.  BY ITS ACQUISITION HEREOF, THE HOLDER (1) REPRESENTS THAT IT IS A “QUALIFIED INSTITUTIONAL BUYER” (AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT); (2) AGREES THAT IT WILL NOT, PRIOR TO EXPIRATION OF THE HOLDING PERIOD APPLICABLE TO SALES OF THIS NOTE UNDER RULE 144(K) UNDER THE SECURITIES ACT (OR ANY SUCCESSOR PROVISION), RESELL OR OTHERWISE TRANSFER THIS NOTE OR THE COMMON STOCK ISSUABLE UPON CONVERSION OF THIS NOTE EXCEPT (A) TO AMYLIN PHARMACEUTICALS, INC. OR ANY SUBSIDIARY THEREOF, (B) TO A QUALIFIED INSTITUTIONAL BUYER IN COMPLIANCE WITH RULE 144A UNDER THE SECURITIES ACT, (C) PURSUANT TO THE EXEMPTION FROM REGISTRATION PROVIDED BY RULE 144 UNDER THE SECURITIES ACT (IF AVAILABLE) OR (D) PURSUANT TO A REGISTRATION STATEMENT WHICH HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT (AND WHICH CONTINUES TO BE EFFECTIVE AT THE TIME OF SUCH TRANSFER); (3) PRIOR TO SUCH TRANSFER (OTHER THAN A TRANSFER PURSUANT TO CLAUSE  2(D) ABOVE), IT WILL FURNISH TO J.P. MORGAN TRUST COMPANY, NATIONAL ASSOCIATION, AS TRUSTEE (OR A SUCCESSOR TRUSTEE, AS APPLICABLE), SUCH CERTIFICATIONS, LEGAL OPINIONS OR OTHER INFORMATION AS THE TRUSTEE MAY REASONABLY REQUIRE TO CONFIRM THAT SUCH TRANSFER IS BEING MADE PURSUANT TO AN EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION

REQUIREMENTS OF THE SECURITIES ACT; AND (4) AGREES THAT IT WILL DELIVER TO EACH PERSON TO WHOM THIS NOTE IS TRANSFERRED A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND.  IN CONNECTION WITH ANY TRANSFER OF THIS NOTE PRIOR TO THE EXPIRATION OF THE HOLDING PERIOD APPLICABLE TO SALES OF THIS NOTE UNDER RULE 144(k) UNDER THE SECURITIES ACT (OR ANY SUCCESSOR PROVISION), THE HOLDER MUST CHECK THE APPROPRIATE BOX SET FORTH ON THE REVERSE HEREOF RELATING TO THE MANNER OF SUCH TRANSFER AND SUBMIT THIS CERTIFICATE TO J.P. MORGAN TRUST COMPANY, NATIONAL ASSOCIATION, AS TRUSTEE (OR A SUCCESSOR TRUSTEE, AS APPLICABLE).  THIS LEGEND WILL BE REMOVED UPON THE EARLIER OF THE TRANSFER OF THE NOTE EVIDENCED HEREBY PURSUANT TO CLAUSE 2(D) ABOVE OR UPON ANY TRANSFER OF THIS NOTE UNDER RULE 144 UNDER THE SECURITIES ACT (OR ANY SUCCESSOR PROVISION).  THE INDENTURE CONTAINS A PROVISION REQUIRING THE TRUSTEE TO REFUSE TO REGISTER ANY TRANSFER OF THIS NOTE IN VIOLATION OF THE FOREGOING RESTRICTION.

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AMYLIN PHARMACEUTICALS, INC.

2.50% CONVERTIBLE SENIOR NOTE DUE 2011

Amylin Pharmaceuticals, Inc., a corporation duly organized and validly existing under the laws of the State of Delaware (herein called the “Company”, which term includes any successor corporation under the Indenture referred to on the reverse hereof), for value received hereby promises to pay to CEDE & CO. or its registered assigns, the principal sum set forth on Schedule I hereto on April 15, 2011 at the office or agency of the Company maintained for that purpose in accordance with the terms of the Indenture, in such coin or currency of the United States of America as at the time of payment shall be legal tender for the payment of public and private debts, and to pay interest, semiannually on April 15 and October 15 of each year, commencing October 15, 2004, on said principal sum, in like coin or currency, at the rate per annum of 2.50%, from the date hereof.  Except as otherwise provided in the Indenture, the interest payable on this Note pursuant to the Indenture on any April 15 or October 15 will be paid to the Person entitled thereto as it appears in the Note Register at the close of business on the record date, which shall be the April 1 or October 1 (whether or not a Business Day) next preceding such April 15 or October 15, as provided in the Indenture; provided that any such interest not punctually paid or duly provided for shall be payable as provided in Section 6.01 of the Indenture.  Interest on the Notes shall be computed on the basis of a 360-day year of twelve 30-day months.

The Company shall pay interest (i) on any Notes in certificated form by check mailed to the address of the Person entitled thereto as it appears in the Note Register (or, upon written notice by such Person, by wire transfer in immediately available funds, if such Person is entitled to interest on aggregate principal in excess of $2.0 million) or (ii) on any Global Note by wire transfer of immediately available funds to the account of the Depositary or its nominee.

The Company promises to pay interest on overdue principal, premium, if any, and (to the extent that payment of such interest is enforceable under applicable law) interest and Liquidated Damages, if any, at the stated rate per annum of the Notes.

Reference is made to the further provisions of this Note set forth on the reverse hereof, including, without limitation, provisions giving the holder of this Note the right to convert this Note into Common Stock of the Company on the terms and subject to the limitations referred to on the reverse hereof and as more fully specified in the Indenture.  Such further provisions shall for all purposes have the same effect as though fully set forth at this place.

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This Note shall be deemed to be a contract made under the laws of the State of New York, and for all purposes shall be construed in accordance with and governed by the laws of the State of New York, without regard to conflicts of laws principles thereof.

This Note shall not be valid or become obligatory for any purpose until the certificate of authentication hereon shall have been manually signed by the Trustee or a duly authorized authenticating agent under the Indenture.

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IN WITNESS WHEREOF, the Company has caused this Note to be duly executed.

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TRUSTEE’S CERTIFICATE OF AUTHENTICATION

This is one of the Notes described in the within-named Indenture.

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FORM OF REVERSE OF NOTE

AMYLIN PHARMACEUTICALS, INC.

2.50% CONVERTIBLE SENIOR NOTE DUE 2011

This Note is one of a duly authorized issue of Notes of the Company, designated as its 2.50% Convertible Senior Notes due 2011 (herein called the “Notes”), limited in aggregate principal amount to $175,000,000 (or if the Company sells an additional $25,000,000 principal amount of its Notes pursuant to the option of the Initial Purchasers granted pursuant to the Purchase Agreement dated as of March 31, 2004 between the Company and the Initial Purchasers, limited in the aggregate principal amount to $200,000,000), issued and to be issued under and pursuant to an Indenture dated as of April 6, 2004 (herein called the “Indenture”), between the Company and J.P. Morgan Trust Company, National Association, as trustee (herein called the “Trustee”), to which Indenture and all indentures supplemental thereto reference is hereby made for a description of the rights, limitations of rights, obligations, duties and immunities thereunder of the Trustee, the Company and the holders of the Notes.

The Notes are issuable in fully registered form, without coupons, in denominations of $1,000 principal amount and any multiple of $1,000.  Upon due presentment for registration of transfer of this Note at the office or agency of the Company maintained for that purpose in accordance with the terms of the Indenture, a new Note or Notes of authorized denominations for an equal aggregate principal amount will be issued to the transferee in exchange thereof, subject to the limitations provided in the Indenture, without charge except for any tax, assessment or other governmental charge imposed in connection therewith.

The Notes are not subject to redemption through the operation of any sinking fund and may not be redeemed at the option of the Company prior to maturity other than pursuant to Section 3.06 of the Indenture.

If a Designated Event occurs at any time prior to maturity of the Notes, this Note will be redeemable at the option of the holder of this Note at a redemption price equal to 100% of the principal amount hereof, together with accrued interest and Liquidated Damages, if any to (but excluding) the redemption date, as provided in Article 3 of the Indenture.

At the Company’s option (subject to the conditions set forth in the Indenture), pursuant to the provisions of Section 3.02 of the Indenture, the Company may, upon the occurrence of a Designated Event, pay the redemption price in the Company’s Common Stock (or that of the Company’s parent, if applicable) or a combination of cash and the applicable common stock.

Subject to compliance with the provisions of the Indenture, prior to the close of business on the final maturity date of the Notes, the holder hereof has the

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right, at its option, to convert each $1,000 principal amount of this Note into 29.1117 shares (the “Conversion Rate”) of the Company’s Common Stock, as such shares shall be constituted at the date of conversion and subject to adjustment from time to time as provided in the Indenture.

No adjustment in respect of interest on any Note converted or dividends on any shares issued upon conversion of such Note will be made upon any conversion except as set forth in the next sentence.  If this Note (or portion hereof) is surrendered for conversion during the period from the close of business on any record date for the payment of interest to the close of business on the Business Day preceding the following interest payment date, this Note (or portion hereof being converted) must be accompanied by payment, in immediately available funds or other funds acceptable to the Company, of an amount equal to the interest otherwise payable on such interest payment date on the principal amount being converted; provided that no such payment shall be required (1) if the Company has specified a redemption date following a Designated Event that is after a record date and on or prior to the next interest payment date or (2) to the extent of any overdue interest at the time of conversion with respect to this Note.

No fractional shares will be issued upon any conversion, but an adjustment and payment in cash will be made, as provided in the Indenture, in respect of any fraction of a share which would otherwise be issuable upon the surrender of any Note or Notes for conversion.

A Note in respect of which a holder is exercising its right to require redemption upon a Designated Event may be converted up to the close of business on the business day immediately preceding the applicable redemption date.

In case an Event of Default shall have occurred and be continuing, the principal of, premium, if any, and accrued interest, on all Notes may be declared by either the Trustee or the holders of not less than 25% in aggregate principal amount of the Notes then outstanding, and upon said declaration shall become, due and payable, in the manner, with the effect and subject to the conditions provided in the Indenture.

The Indenture contains provisions permitting the Company and the Trustee, with the consent of the holders of at least a majority in aggregate principal amount of the Notes at the time outstanding, to execute supplemental indentures adding any provisions to or changing in any manner or eliminating any of the provisions of the Indenture or of any supplemental indenture or modifying in any manner the rights of the holders of the Notes, subject to the exceptions set forth in Section 10.02 of the Indenture.  Subject to the provisions of the Indenture, the holders of a majority in aggregate principal amount of the Notes at the time outstanding may on behalf of the holders of all of the Notes waive any past, current or future breach of any provision of the Indenture, default or Event of Default, in each case subject to the exceptions set forth in the Indenture.  Any such consent or waiver by the holder of this Note (unless revoked as provided in

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the Indenture) shall be conclusive and binding upon such holder and upon all future holders and owners of this Note and any Notes which may be issued in exchange or substitution hereof, irrespective of whether or not any notation thereof is made upon this Note or such other Notes.

No reference herein to the Indenture and no provision of this Note or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional, to pay the principal of and any premium and interest, on this Note at the place, at the respective times, at the rate and in the coin or currency herein prescribed.

The Company, the Trustee, any authenticating agent, any paying agent, any conversion agent and any Note Registrar may deem and treat the registered holder hereof as the absolute owner of this Note (whether or not this Note shall be overdue and notwithstanding any notation of ownership or other writing hereon made by anyone other than the Company or any Note Registrar) for the purpose of receiving payment hereof, or on account hereof, for the conversion hereof and for all other purposes, and neither the Company nor the Trustee nor any other authenticating agent nor any paying agent nor other conversion agent nor any Note Registrar shall be affected by any notice to the contrary.  All payments made to or upon the order of such registered holder shall, to the extent of the sum or sums paid, satisfy and discharge liability for monies payable on this Note.

No recourse for the payment of the principal of or any premium or interest on this Note, or for any claim based hereon or otherwise in respect hereof, and no recourse under or upon any obligation, covenant or agreement of the Company in the Indenture or any supplemental indenture or in any Note, or because of the creation of any indebtedness represented thereby, shall be had against any incorporator, stockholder, employee, agent, officer or director or subsidiary, as such, past, present or future, of the Company or of any successor corporation, either directly or through the Company or any successor corporation, whether by virtue of any constitution, statute or rule of law or by the enforcement of any assessment or penalty or otherwise, all such liability being, by acceptance hereof and as part of the consideration for the issue hereof, expressly waived and released.

Terms used in this Note and defined in the Indenture are used herein as therein defined.

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ABBREVIATIONS

The following abbreviations, when used in the inscription of the face of this Note, shall be construed as though they were written out in full according to applicable laws or regulations.

Additional abbreviations may also be used though not in the above list.

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CONVERSION NOTICE

The undersigned registered owner of this Note hereby irrevocably exercises the option to convert this Note, or the portion thereof (which is $1,000 or a multiple thereof) below designated, into shares of Common Stock of Amylin Pharmaceuticals, Inc. in accordance with the terms of the Indenture referred to in this Note, and directs that the shares issuable and deliverable upon such conversion, together with any check in payment for fractional shares and any Notes representing any unconverted principal amount hereof, be issued and delivered to the registered holder hereof unless a different name has been indicated below.  Capitalized terms used herein but not defined shall have the meanings ascribed to such terms in the Indenture.  If shares or any portion of this Note not converted are to be issued in the name of a person other than the undersigned, the undersigned will provide the appropriate information below and pay all transfer taxes payable with respect thereto.  Any amount required to be paid by the undersigned on account of interest accompanies this Note.

Fill in the registration of shares of Common Stock if to be issued, and Notes if to be delivered, other than to and in the name of the registered holder:

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OPTION TO ELECT REDEMPTION
UPON A DESIGNATED EVENT

The undersigned registered owner of this Note hereby irrevocably acknowledges receipt of a notice from Amylin Pharmaceuticals, Inc. (the “Company”) as to the occurrence of a Designated Event with respect to the Company and requests and instructs the Company to redeem the entire principal amount of this Note, or the portion thereof (which is $1,000 or a multiple thereof) below designated, in accordance with the terms of the Indenture referred to in this Note at the price of 100% of such entire principal amount or portion thereof, together with accrued interest and Liquidated Damages, if any, to, but excluding, the Designated Event Redemption Date, to the registered holder hereof.  Capitalized terms used herein but not defined shall have the meanings ascribed to such terms in the Indenture.

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ASSIGNMENT

For value received                                                          hereby sell(s) assign(s) and transfer(s) unto                                                          (Please insert social security or other Taxpayer Identification Number of assignee) the within Note, and hereby irrevocably constitutes and appoints                                                          attorney to transfer said Note on the books of the Company, with full power of substitution in the premises.

In connection with any transfer of the Note prior to the expiration of the holding period applicable to sales thereof under Rule 144(k) under the Securities Act (or any successor provision) (other than any transfer pursuant to a registration statement that has been declared effective under the Securities Act), the undersigned confirms that such Note is being transferred:

o                                    To Amylin Pharmaceuticals, Inc. or a subsidiary thereof; or

o                                    To a “qualified institutional buyer” in compliance with Rule 144A under the Securities Act of 1933, as amended; or

o                                    Pursuant to and in compliance with Rule 144 under the Securities Act of 1933, as amended; or

o                                    Pursuant to a Registration Statement which has been declared effective under the Securities Act of 1933, as amended, and which continues to be effective at the time of transfer;

and unless the Note has been transferred to Amylin Pharmaceuticals, Inc. or a subsidiary thereof, the undersigned confirms that such Note is not being transferred to an “affiliate” of the Company as defined in Rule 144 under the Securities Act of 1933, as amended.

Unless one of the boxes is checked, the Trustee will refuse to register any of the Notes evidenced by this certificate in the name of any person other than the registered holder thereof.

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NOTICE: The signature on the Conversion Notice, the Option to Elect Redemption Upon a Designated Event, or the Assignment must correspond with the name as written upon the face of the Note in every particular without alteration or enlargement or any change whatever.

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Schedule I

AMYLIN PHARMACEUTICALS, INC.

2.50% Convertible Senior Note due 2011

No.  1

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