
<PAGE>   1
This announcement is neither an offer to purchase nor a solicitation of an offer
 to sell Shares (as defined below). The Offer (as defined below) is made solely
    by the Offer to Purchase dated August 14, 1997 and the related Letter of
Transmittal and any amendments or supplements thereto, and is being made to all
holders of Shares. The Offer is not being made to, nor will tenders be accepted
 from or on behalf of, holders of Shares in any jurisdiction in which the making
of the Offer or the acceptance thereof would not be in compliance with the laws
 of such jurisdiction. In any jurisdictions where securities, blue sky or other
laws require the Offer to be made by a licensed broker or dealer, the Offer will
  be deemed to be made on behalf of the Purchaser (as defined below) by Credit
Suisse First Boston Corporation (the "Dealer Manager") or one or more registered
        brokers or dealers licensed under the laws of such jurisdiction.

                      NOTICE OF OFFER TO PURCHASE FOR CASH
                     ALL OUTSTANDING SHARES OF COMMON STOCK
                                       OF
                          AMERICAN MEDSERVE CORPORATION
                                       AT
                              $18.00 NET PER SHARE
                                       BY
                           OMNICARE ACQUISITION CORP.
                          A WHOLLY OWNED SUBSIDIARY OF
                                 OMNICARE, INC.

    Omnicare Acquisition Corp., a Delaware corporation (the "Purchaser") and a
wholly owned subsidiary of Omnicare, Inc., a Delaware corporation (the
"Parent"), is offering to purchase all outstanding shares of Common Stock, par
value $0.01 per share (the "Shares"), of American Medserve Corporation, a
Delaware corporation (the "Company"), at a price of $18.00 per Share, net to the
seller in cash, without interest thereon (the "Offer Price"), upon the terms and
subject to the conditions set forth in the Offer to Purchase dated August 14,
1997 (the "Offer to Purchase"), and in the related Letter of Transmittal (which,
as amended or supplemented from time to time, together constitute the "Offer").
Tendering stockholders who hold Shares in their name will not be obligated to
pay brokerage fees or commissions to the Dealer Manager, the Depository (as
defined below) or the Information Agent (as defined below) or, subject to
Instruction 6 of the Letter of Transmittal, transfer taxes on the purchase of
Shares pursuant to the Offer. The purpose of the Offer is to acquire for cash as
many outstanding Shares as possible as the first step in a negotiated
acquisition of the entire equity interest in the Company. Following the
consummation of the Offer, the Purchaser intends to effect the Merger (as
defined below).

  THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY
      TIME, ON THURSDAY, SEPTEMBER 11, 1997, UNLESS THE OFFER IS EXTENDED.

    The Offer is being made pursuant to the Agreement and Plan of Merger, dated
as of August 7, 1997 (the "Merger Agreement"), by and among the Parent, the
Purchaser and the Company. The Merger Agreement provides, among other things,
for the commencement of the Offer by the Purchaser, and further provides that,
following the purchase of Shares pursuant to the Offer and promptly after the
satisfaction or waiver of certain conditions and in accordance with the Delaware
General Corporation Law, the Purchaser will be merged with and into the Company
(the "Merger"). Following consummation of the Merger, the Company will continue
as the surviving corporation and will be a wholly owned subsidiary of the
Parent. At the effective time of the Merger, each outstanding Share (except for
Shares held in the treasury of the Company or owned by the Purchaser, Parent or
any of Parent's other wholly owned subsidiaries and Shares held by stockholders
properly exercising their appraisal rights under the Delaware General
Corporation Law) will be converted into the right to receive the Offer Price (or
any higher price per Share paid for Shares pursuant to the Offer).

    THE BOARD OF DIRECTORS OF THE COMPANY HAS UNANIMOUSLY DETERMINED THAT THE
OFFER AND THE MERGER ARE FAIR TO, AND IN THE BEST INTERESTS OF, THE COMPANY'S
STOCKHOLDERS, HAS APPROVED THE MERGER AGREEMENT AND THE TRANSACTIONS
CONTEMPLATED THEREBY, INCLUDING THE OFFER AND THE MERGER, AND RECOMMENDS THAT
THE STOCKHOLDERS ACCEPT THE OFFER AND TENDER THEIR SHARES PURSUANT TO THE OFFER.

    THE OFFER IS CONDITIONED UPON, AMONG OTHER THINGS, (1) THERE BEING VALIDLY
TENDERED AND NOT WITHDRAWN PRIOR TO THE EXPIRATION DATE (AS DEFINED BELOW) THAT
NUMBER OF SHARES WHICH REPRESENTS AT LEAST A MAJORITY OF THE SHARES OUTSTANDING
ON A FULLY-DILUTED BASIS (THE "MINIMUM CONDITION") AND (2) ANY WAITING PERIOD
UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976, AS AMENDED, AND
THE REGULATIONS THEREUNDER APPLICABLE TO THE PURCHASE OF THE SHARES PURSUANT TO
THE OFFER HAVING EXPIRED OR BEEN TERMINATED.

    For purposes of the Offer, the Purchaser will be deemed to have accepted for
payment, and thereby purchased, Shares validly tendered and not properly
withdrawn as, if and when the Purchaser gives oral or written notice to First
Chicago Trust Company of New York, as the Depositary (the "Depositary"), of the
Purchaser's acceptance of such Shares for payment pursuant to the Offer. In all
cases, upon the terms and subject to the conditions of the Offer, payment for
Shares purchased pursuant to the Offer will be made by deposit of the purchase
price therefor with the Depositary, which will act as agent for tendering
stockholders for the purpose of receiving payment from the Purchaser and
transmitting payment to validly tendering stockholders. In all cases, payment
for Shares purchased pursuant to the Offer will be made only after timely
receipt by the Depositary of (i) certificates for such Shares (or a confirmation
of a book-entry transfer of such Shares into the Depositary's account at The
Depository Trust Company or the Philadelphia Depository Trust Company (each a
"Book-Entry Transfer Facility"), pursuant to the procedures set forth in the
Offer to Purchase and the Letter of Transmittal), (ii) the Letter of Transmittal
(or a facsimile thereof), properly completed and duly executed, with required
signature guarantees, or an Agent's Message (as defined in the Offer to
Purchase), in connection with a book-entry transfer and (iii) all other
documents required by the Letter of Transmittal. Under no circumstances will
interest on the purchase price for Shares be paid by the Purchaser by reason of
any delay in making such payment.

    The term "Expiration Date" shall mean 12:00 Midnight, New York City Time, on
Thursday, September 11, 1997, unless and until the Purchaser, in accordance with
the terms of the Offer and the Merger Agreement, shall have extended the period
of time during which the Offer is open, in which event the term "Expiration
Date" shall mean the latest time and date at which the Offer, as so extended by
the Purchaser, shall expire. Subject to the terms of the Merger Agreement and
the applicable rules and regulations of the Securities and Exchange Commission
(the "Commission"), the Purchaser expressly reserves the right, in its sole
discretion, at any time or from time to time, and regardless of whether any of
the events set forth in Section 14 of the Offer to Purchase shall have occurred
or shall have been determined by the Purchaser to have occurred, (a) if,
immediately prior to the Expiration Date of the Offer, the Shares tendered and
not withdrawn pursuant to the Offer equal less than 90% of the outstanding
Shares but more than 80% of the outstanding Shares, to extend the Offer for a
period not to exceed seven business days, notwithstanding that all conditions to
the Offer are satisfied as of such date, and thereby delay acceptance for
payment of and the payment for any Shares, by giving oral or written notice of
such extension to the Depositary and (b) prior to the Expiration Date, to waive
any of the conditions set forth in Section 14 of the Offer to Purchase (other
than the Minimum Condition) and to make any other changes in the terms and
conditions of the Offer by giving oral or written notice of such waiver or
amendment to the Depositary. There can be no assurance that the Purchaser will
exercise its right to extend the Offer.

     The Offer is subject to certain conditions set forth in the Offer to
Purchase. If, by the Expiration Date any or all of the conditions to the Offer
have not been satisfied or waived, the Purchaser reserves the right (but shall
not be obligated), in its sole discretion, subject to the terms of the Merger
Agreement and the applicable rules and regulations of the Commission, (a) to
terminate the Offer and not accept for payment or pay for any Shares and return
all tendered Shares to tendering stockholders, (b) prior to the Expiration Date,
to waive all the unsatisfied conditions (other than the Minimum Condition) and
accept for payment and pay for all Shares validly tendered prior to the
Expiration Date, or (c) extend the Offer and, subject to the right of
stockholders to withdraw Shares during such extension, retain the Shares that
have been tendered during the period or periods for which the Offer is extended.
Any extension, delay in payment, termination or amendment will be followed as
promptly as practicable by public announcement thereof, the announcement in the
case of an extension to be issued not later than 9:00 A.M., New York City Time,
on the next business day after the previously scheduled Expiration Date. Without
limiting the manner in which the Purchaser may choose to make any public
announcement, the Purchaser currently intends to make announcements by issuing a
press release to the Dow Jones News Service. During any such extension, all
Shares previously tendered and not properly withdrawn will remain subject to the
Offer, subject to the right of a tendering stockholder to withdraw such
stockholder's Shares.

    Tenders of Shares made pursuant to the Offer are irrevocable except as
otherwise provided below. Shares tendered pursuant to the Offer may be withdrawn
at any time prior to the Expiration Date and, unless theretofore accepted for
payment by the Purchaser pursuant to the Offer, may also be withdrawn at any
time after October 12, 1997. For a withdrawal to be effective, a written,
telegraphic or facsimile transmission notice of withdrawal must be timely
received by the Depositary at its address set forth on the back cover of the
Offer to Purchase. Any such notice of withdrawal must specify the name of the
person who tendered the Shares to be withdrawn, the number of Shares to be
withdrawn and the name of the registered holder of such Shares, if different
from that of the person who tendered such Shares. If certificates evidencing
Shares to be withdrawn have been delivered or otherwise identified to the
Depositary, then, prior to the physical release of such certificates, the serial
numbers shown on such certificates must be submitted to the Depositary and the
signature(s) on the notice of withdrawal must be guaranteed by an Eligible
Institution (as defined in the Offer to Purchase), unless such Shares have been
tendered for the account of an Eligible Institution. If Shares have been
tendered pursuant to the procedure for book-entry transfer as set forth under
Section 3 in the Offer to Purchase, any notice of withdrawal must also specify
the name and number of the account at the Book-Entry Transfer Facility to be
credited with the withdrawn Shares. All questions as to the form and validity
(including time of receipt) of notices of withdrawal will be determined by the
Purchaser, in its sole discretion, whose determination will be final and
binding. No withdrawal of Shares shall be deemed to have been properly made
until all defects and irregularities have been cured or waived. None of the
Purchaser, Parent, the Dealer Manager, the Depositary, the Information Agent or
any other person will be under any duty to give notification of any defects or
irregularities in any notice of withdrawal or incur any liability for failing to
give such notification.

    The information required to be disclosed by Rule 14d-6(e)(1)(vii) of the
General Rules and Regulations under the Securities Exchange Act of 1934, as
amended, is contained in the Offer to Purchase and is incorporated herein by
reference.

    The Company is providing to the Purchaser its list of stockholders and
security position listings for the purpose of disseminating the Offer to holders
of Shares. The Offer to Purchase and the related Letter of Transmittal and other
relevant materials will be mailed to record holders of Shares and will be
furnished to brokers, dealers, commercial banks, trust companies and similar
persons whose names, or the names of whose nominees appear on the Company's
stockholder list or, if applicable, who are listed as participants in a clearing
agency's security position listing for subsequent transmittal to beneficial
owners of Shares.

    THE OFFER TO PURCHASE AND THE RELATED LETTER OF TRANSMITTAL CONTAIN
IMPORTANT INFORMATION WHICH SHOULD BE READ CAREFULLY BEFORE ANY DECISION IS MADE
WITH RESPECT TO THE OFFER.

    Requests for copies of the Offer to Purchase, the Letter of Transmittal and
other tender offer documents may be directed to the Information Agent as set
forth below, and copies will be furnished promptly at the Purchaser's expense.
Questions and requests for assistance may be directed to the Dealer Manager or
the Information Agent at their respective addresses and telephone numbers set
forth below. The Purchaser will not pay any fees or commissions to any broker or
dealer or any other person (other than the Dealer Manager and the Information
Agent) for soliciting tenders of Shares pursuant to the Offer.

                     The Information Agent for the Offer is:
                              D.F. KING & CO., INC.
                                 77 Water Street
                            New York, New York 10005
                          Call Toll Free (800) 697-6975

                      The Dealer Manager for the Offer is:

                             
                      [CREDIT SUISSE FIRST BOSTON LOGO]

                              Eleven Madison Avenue
                          New York, New York 10010-3629
                          Call Toll Free (800) 881-8320




August 14, 1997

