OFFER TO PURCHASE FOR CASH
                     ALL OUTSTANDING SHARES OF COMMON STOCK
                                       OF

                          ESPERION THERAPEUTICS, INC.
                                       BY

                            ENZO ACQUISITION CORP.,
                          A WHOLLY OWNED SUBSIDIARY OF

                                  PFIZER INC.
                                       AT
                                $35.00 PER SHARE

THE OFFER (AS DEFINED HEREIN) AND WITHDRAWAL RIGHTS WILL EXPIRE AT MIDNIGHT, NEW
YORK CITY TIME, ON FEBRUARY 4, 2004, UNLESS THE OFFER IS EXTENDED.

                                                                 January 6, 2004

To Brokers, Dealers, Banks,
Trust Companies and Other Nominees:

     We have been engaged by Enzo Acquisition Corp., a Delaware corporation (the
"Purchaser") and a wholly owned subsidiary of Pfizer Inc., a Delaware
corporation ("Parent"), to act as the information agent (the "Information
Agent") in connection with Purchaser's offer to purchase all of the outstanding
shares of common stock, par value $0.001 per share (the "Shares" or "Company
Common Stock"), of Esperion Therapeutics, Inc., a Delaware corporation
("Esperion" or the "Company"), at a price of $35.00 per share (the "Offer
Price"), net to the seller in cash,, on the terms and subject to the conditions
set forth in Purchaser's Offer to Purchase, dated January 6, 2004 (the "Offer to
Purchase"), and in the Letter of Transmittal (which, together with any
amendments or supplements thereto, collectively constitute the "Offer"). All
references in this letter to Company Common Stock include the Rights to such
common stock. Please furnish copies of the enclosed materials to those of your
clients for whom you hold Shares that are registered in your name or in the name
of your nominee.

     Holders of Shares who wish to tender their Shares but whose certificates
for such Shares (the "Share Certificates") are not immediately available, who
cannot complete the procedures for book-entry transfer on a timely basis, or who
cannot deliver all other required documents to EquiServe Trust, (the
"Depositary"), prior to the Expiration Date (as defined in the Offer to
Purchase) of the Offer must tender their Shares according to the guaranteed
delivery procedure set forth in the Offer to Purchase.

     Enclosed herewith are copies of the following documents:

          1. The Offer to Purchase dated January 6, 2004;

          2. The Letter of Transmittal to be used by stockholders of Esperion to
     tender Shares in the Offer (manually signed facsimile copies of the Letter
     of Transmittal may also be used to tender Shares);

          3. A letter to stockholders of Esperion from Roger S. Newton, of
     Esperion, accompanied by Esperion's Solicitation/Recommendation Statement
     on Schedule 14D-9 filed with the SEC by Esperion which includes the
     recommendation of Esperion's board of directors that Esperion stockholders
     accept the Offer and tender their Shares to Purchaser pursuant to the
     Offer;


          4. A printed form of letter that may be sent to your clients for whose
     account you hold Shares that are registered in your name or in the name of
     your nominee, with space provided for obtaining such clients instructions
     with regard to the Offer;

          5. Notice of Guaranteed Delivery to be used to accept the Offer if
     Share Certificates are not immediately available or if such certificates
     and all other required documents cannot be delivered to the Depositary or
     if the procedures for book-entry transfer cannot be completed on a timely
     basis;

          6. Guidelines for Certification of Taxpayer Identification Number on
     Substitute Form W-9; and

          7. Return envelope addressed to EquiServe Trust as the Depositary for
     the Offer.

     We urge you to contact your clients promptly. Please note that the Offer
and withdrawal rights will expire at Midnight, New York City time, on February
4, 2004, unless the Offer is extended.

     The Offer is being made pursuant to an Agreement and Plan of Merger, dated
as of December 19, 2003 (the "Merger Agreement"), by and among Parent, Purchaser
and Esperion pursuant to which, following the purchase of shares of Company
Common Stock in the Offer and the satisfaction or waiver of certain conditions,
Purchaser will be merged with and into Esperion (the "Merger"), with Esperion
surviving the Merger as a wholly owned subsidiary of Parent. As a result of the
Merger, each outstanding Share (other than shares owned by Purchaser, Esperion
or any stockholder of Esperion who is entitled to and properly exercises
appraisal rights under Delaware law and other than certain shares of unvested
restricted stock which will be cancelled in exchange for payment based on
vesting contingencies) will be converted into the right to receive the price per
Share paid in the Offer in cash, without interest thereon.

     Esperion's board of directors has, at a meeting held on December 19, 2003,
(i) determined that the Merger Agreement and the transactions contemplated
thereby, including the Offer and the Merger, are advisable and in the best
interests of Esperion and its stockholders, (ii) approved the Merger Agreement,
and the transactions contemplated thereby, including the Offer and the Merger,
and (iii) resolved to recommend that the stockholders of Esperion accept the
Offer, tender their shares of common stock pursuant to the Offer and (if
required by applicable law) adopt the Merger Agreement and approve the Merger.

     The Offer is conditioned on, among other things, there being validly
tendered in accordance with the terms of the Offer and not withdrawn prior to
the Expiration Date (as defined in the Offer to Purchase) of the Offer, that
number of Shares that, together with any shares of Company Common Stock then
owned by Parent or any wholly owned subsidiary of Parent (including Purchaser),
represents a majority of the shares of Company Common Stock outstanding on a
fully-diluted basis. (The foregoing condition is referred to as the "Minimum
Condition" in this Offer to Purchase). The Offer is subject to certain other
conditions contained in Section 1 (Terms of the Offer) and Section 13 (Certain
Conditions to the Offer) of the Offer to Purchase.

     On the terms of and subject to the conditions to the Offer, promptly after
the Expiration Date of the Offer, Purchaser will accept for payment, and pay
for, all Shares validly tendered to Purchaser and not withdrawn prior to the
Expiration Date of the Offer. To validly tender Shares in the Offer (i) the
certificate(s) representing the tendered Shares, together with the Letter of
Transmittal (or a facsimile copy of it), properly completed and duly executed,
together with any required signature guarantees, and any other required
documents, must be received by the Depositary prior to the Expiration Date of
the Offer, (ii) in the case of a tender effected pursuant to the book-entry
transfer procedures described in the Offer to Purchase (a) either the Letter of
Transmittal, properly completed and duly executed, together with any required
signature guarantees, or an Agent's Message, (as defined in the Offer to
Purchase), and any other required documents, must be received by the Depositary
prior to the Expiration Date of the Offer and (b) the Shares to be tendered must
be delivered pursuant to the book-entry transfer procedures described in the
Offer to Purchase and a Book-Entry Confirmation (as defined in the Offer to
Purchase), must be received by the Depositary prior to the Expiration Date of
the Offer or (iii) the tendering stockholder must comply with the guaranteed
delivery procedures described in the Offer to Purchase prior to the Expiration
Date of the Offer.

     Neither Purchaser nor Parent will pay any fees or commissions to any broker
or dealer or other person (other than the Depositary and the Information Agent)
in connection with the solicitation of tenders of Shares in connection with the
Offer. You will be reimbursed by Purchaser on request for customary mailing and
handling expenses incurred by you in forwarding the enclosed materials to your
customers. Purchaser will pay or cause to be paid all stock transfer taxes

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applicable to its purchase of Shares pursuant to the Offer, except as otherwise
provided in Instruction 6 of the Letter of Transmittal.

     Questions regarding the Offer, and requests for additional copies of the
enclosed material, may be directed to the Information Agent at our address and
telephone number listed on the back cover of the Offer to Purchase.

                                         Very truly yours,

                                         MORROW & CO., INC.

Nothing contained herein or in the enclosed documents shall render you or any
other person the agent of Purchaser, Parent, Esperion, the Depositary or the
Information Agent or authorize you or any other person to give any information
or make any representation on behalf of any of them with respect to the Offer
not contained in the Offer to Purchase or the Letter of Transmittal for the
Offer.

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