<SUBMISSION>
<ACCESSION-NUMBER>0000950123-01-002393
<TYPE>SC TO-T/A
<PUBLIC-DOCUMENT-COUNT>2
<FILING-DATE>20010319
<GROUP-MEMBERS>INDIGO ACQUISITION CORP
<GROUP-MEMBERS>INVERESK RESEARCH (CANADA) INC
<GROUP-MEMBERS>INVERESK RESEARCH GROUP LTD
<SUBJECT-COMPANY>
<COMPANY-DATA>
<CONFORMED-NAME>CLINTRIALS RESEARCH INC
<CIK>0000870978
<ASSIGNED-SIC>8734
<IRS-NUMBER>621406017
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>SC TO-T/A
<ACT>34
<FILE-NUMBER>005-48381
<FILM-NUMBER>1571526
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>11000 WESTON PARKWAY
<CITY>CARY
<STATE>NC
<ZIP>27513
<PHONE>9194622556
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>11000 WESTON PARKWAY
<CITY>CARY
<STATE>NC
<ZIP>27513
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>CLINTRIALS INC
<DATE-CHANGED>19930930
</FORMER-COMPANY>
</SUBJECT-COMPANY>
<FILED-BY>
<COMPANY-DATA>
<CONFORMED-NAME>INVERESK RESEARCH GROUP LTD
<CIK>0001135362
<ASSIGNED-SIC>
<IRS-NUMBER>000000000
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>SC TO-T/A
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>ELPHINSTONE RESEARCH CENTRE
<STREET2>TRANENT, EAST LOTHIAN EH33 2NE
<CITY>UNITED KINGDOM
<PHONE>4401875614545
</BUSINESS-ADDRESS>
</FILED-BY>
<DOCUMENT>
<TYPE>SC TO-T/A
<SEQUENCE>1
<FILENAME>y46719a1scto-ta.txt
<DESCRIPTION>AMENDMENT NO. 1 TO SCHEDULE TO
<TEXT>

<PAGE>   1



                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                            -------------------------

                               AMENDMENT NO. 1 TO
                                   SCHEDULE TO
                                 (RULE 14D-100)

               TENDER OFFER STATEMENT PURSUANT TO SECTION 14(D)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

                            CLINTRIALS RESEARCH INC.
                       (Name of Subject Company (Issuer))

                            INDIGO ACQUISITION CORP.
                          a wholly owned subsidiary of
                         INVERESK RESEARCH (CANADA) INC.
                          a wholly owned subsidiary of
                         INVERESK RESEARCH GROUP LIMITED
                       (Name of Filing Persons (Offerors))

                          COMMON STOCK, $0.01 PAR VALUE
                         (Title of Class of Securities)

                                    188767107
                      (CUSIP Number of class of securities)

                                STEWART G. LESLIE
                         INVERESK RESEARCH GROUP LIMITED
                           ELPHINSTONE RESEARCH CENTRE
                         TRANENT, EAST LOTHIAN EH33 2NE
                            SCOTLAND, UNITED KINGDOM
                               +44 (1875) 614-545

        (Name, Address and Telephone No. of Person Authorized to Receive
             Notices and Communications on Behalf of Filing Persons)

                                 with a copy to:
                               JOHN A. HEALY, ESQ.
                       CLIFFORD CHANCE ROGERS & WELLS LLP
                                200 PARK AVENUE,
                            NEW YORK, NEW YORK 10166
                                 (212) 878-8000

                            -------------------------

                            CALCULATION OF FILING FEE

--------------------------------------------------------------------------------
       TRANSACTION VALUATION                         AMOUNT OF FILING FEE
         $123,490,056                                       $24,699*
--------------------------------------------------------------------------------

    * Previously paid.


   |_| Check the box if the filing relates solely to preliminary communications
made before commencement of a tender offer.

       Check the appropriate boxes below to designate any transactions to which
the statement relates:

       |X|    third-party tender offer subject to Rule 14d-1.
       |_|    issuer tender offer subject to Rule 13e-4.
       |_|    going-private transaction subject to Rule 13e-3.
       |_|    amendment to Schedule 13D under Rule 13d-2.


   Check the following box if the filing is a final amendment reporting the
results of the tender offer: |_|




<PAGE>   2



                         AMENDMENT NO. 1 TO SCHEDULE TO

         This Amendment No. 1 amends and supplements the Tender Offer Statement
on Schedule TO, originally filed with the Securities and Exchange Commission on
March 5, 2001 (the "Schedule TO"), relating to the offer by Indigo Acquisition
Corp., a Delaware corporation ("Purchaser"), which is a wholly owned subsidiary
of Inveresk Research (Canada) Inc., a corporation organized under the laws of
Canada ("Inveresk Canada"), which, in turn, is a wholly owned subsidiary of
Inveresk Research Group Limited, a company organized under the laws of Scotland
("Parent"), to purchase all of the outstanding shares of common stock, par value
$0.01 per share (the "Shares"), of ClinTrials Research Inc., a Delaware
corporation (the "Company") at a price of $6.00 per Share, net to the seller in
cash, upon the terms and subject to the conditions set forth in the Offer to
Purchase, dated March 5, 2001 (the "Offer to Purchase"), a copy of which was
attached as Exhibit (a)(1) to the Schedule TO, and in the related Letter of
Transmittal, a copy of which was attached to the Schedule TO as Exhibit (a)(2).

SCHEDULE TO

         The Schedule TO is hereby supplemented and/or amended as provided
below.

ITEM 11.  ADDITIONAL INFORMATION.

         Item 11 of the Schedule TO is amended by adding the following:

         Parent has been notified that it has received clearance from the German
Federal Cartel Office to proceed with the completion of the Offer and the
Merger. The Offer remains conditioned upon, among other things, the expiration
of the applicable waiting period under the U.S. Hart-Scott-Rodino Antitrust
Improvements Act of 1976, as amended.

         For additional information regarding the clearance received from the
German Federal Cartel Office, see the text of the press release filed as an
exhibit hereto.

ITEM 12.  EXHIBITS.

         Item 12 of the Schedule TO is amended by adding the following:

         (a)(9) Press release issued by Parent, dated March 19, 2001, announcing
                the receipt of clearance from the German Federal Cartel Office
                to proceed with the completion of the Offer and the Merger.




                                      -2-


<PAGE>   3



                                    SIGNATURE

         After due inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

Date: March 19, 2001                  INDIGO Acquisition Corp.


                                      /S/ WALTER NIMMO
                                      --------------------------------------
                                      Name:   Walter Nimmo
                                      Title:  President


                                      /S/ ALASTAIR MCEWAN
                                      --------------------------------------
                                      Name:   Alastair McEwan
                                      Title:  Vice President

                                      INVERESK RESEARCH (CANADA) INC.


                                      /S/ WALTER NIMMO
                                      --------------------------------------
                                      Name:   Walter Nimmo
                                      Title:  President

                                      INVERESK RESEARCH GROUP LIMITED


                                      /S/ WALTER NIMMO
                                      --------------------------------------
                                      Name:   Walter Nimmo
                                      Title:  Chief Executive Officer


                                      /S/ STEWART LESLIE
                                      --------------------------------------
                                      Name:   Stewart Leslie
                                      Title:  Director and Company Secretary


                                     - 3 -
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-99.A.9
<SEQUENCE>2
<FILENAME>y46719a1ex99-a_9.txt
<DESCRIPTION>PRESS RELEASE
<TEXT>

<PAGE>   1
                                                                EXHIBIT 99(a)(9)


INVERESK RECEIVES GERMAN CLEARANCE FOR ACQUISITION OF CLINTRIALS RESEARCH INC.,
SCOTLAND, MARCH 19, 2001 - Inveresk Research Group Limited received notification
of clearance from the German Federal Cartel Office to proceed with Inveresk's
offer to purchase all of the outstanding shares of common stock of ClinTrials
Research Inc. (NASDAQ: CCRO) and the proposed merger of an indirect wholly owned
subsidiary of Inveresk into ClinTrials. This satisfies an important condition of
Inveresk's purchase of any ClinTrials shares tendered in the offer. Inveresk's
completion of the offer remains conditioned upon, among other things, the
expiration of the applicable waiting period under U.S. antitrust law.

ClinTrials is a global contract research organization headquartered near
Research Triangle Park, North Carolina with offices in Maidenhead, England;
Glasgow, Scotland; Montreal, Canada; Brussels, Belgium; Paris, France;
Melbourne, Australia; Tel Aviv, Israel; Milan, Italy; Warsaw, Poland; Madrid,
Spain; and Munich, Germany. With more than 1,500 employees, ClinTrials provides
comprehensive research services, including monitoring, data management and
biostatistics, medical and regulatory services to pharmaceutical, biotechnology
and medical device clients.

Headquartered near Edinburgh, Scotland, Inveresk is a leading European provider
of contract research services, primarily to the pharmaceutical and biotechnology
industry.

THIS RELEASE CONTAINS FORWARD-LOOKING STATEMENTS, INCLUDING STATEMENTS ABOUT
FUTURE BUSINESS OPERATIONS, FINANCIAL PERFORMANCE AND MARKET CONDITIONS. SUCH
FORWARD-LOOKING STATEMENTS INVOLVE RISKS AND UNCERTAINTIES INHERENT IN BUSINESS
FORECASTS. THIS RELEASE IS NEITHER AN OFFER TO PURCHASE NOR A SOLICITATION OF AN
OFFER TO SELL SECURITIES OF CLINTRIALS RESEARCH INC. THE TENDER OFFER IS BEING
MADE SOLELY BY AN OFFER TO PURCHASE AND RELATED LETTER OF TRANSMITTAL
DISSEMINATED UPON THE COMMENCEMENT OF THE TENDER OFFER AND AMENDED FROM TIME TO
TIME. SHAREHOLDERS OF CLINTRIALS RESEARCH INC. SHOULD READ THE TENDER OFFER
STATEMENT BECAUSE IT CONTAINS IMPORTANT INFORMATION. THESE DOCUMENTS ARE
AVAILABLE TO CLINTRIALS SHAREHOLDERS AT NO CHARGE AND ARE ALSO AVAILABLE FOR
FREE AT THE SEC'S WEB SITE (HTTP://WWW.SEC.GOV).

CONTACT: GCI Christopher Gordon (212) 886-3428 ClinTrials Research, Inc. Paul
Ottaviano Chief Executive Officer (919) 460-9005




</TEXT>
</DOCUMENT>
</SUBMISSION>
