<PAGE>

                                                                Exhibit 10.17(A)

                               FIRST AMENDMENT TO
                            INVESTOR RIGHTS AGREEMENT

         THIS FIRST AMENDMENT TO INVESTOR RIGHTS AGREEMENT (the "First
Amendment") is entered into as of this 22 day of January, 2001, by and among
Animas Corporation, a Delaware corporation (the "Company") and certain
individuals and entities who are identified as "Investors" in an Investor Rights
Agreement, dated as of January 28, 2000 (the "Original Agreement"),which
individuals and entities are identified on the signature pages to this First
Amendment (collectively, for purposes of this Amendment, the "Series A
Investors"). Capitalized terms used but not otherwise defined herein shall have
the meanings set forth in the Original Agreement.

                                   BACKGROUND

         WHEREAS, the Series A Investors hold shares of the Company's Series A
Preferred Stock, $.01 par value per share (the "Series A Preferred Stock"), and
possess certain registration and other rights with respect to such Series A
Preferred Stock under the Original Agreement; and

         WHEREAS, the Company has agreed to sell and issue up to 1,500,000
shares of its Series B Convertible Preferred Stock, $.01 par value per share
(the "Series B Preferred Stock") to certain new investors (the "Series B
Investors"), pursuant to a Series B Convertible Preferred Stock Purchase
Agreement, dated January 22, 2001 (the "Series B Purchase Agreement"); and

         WHEREAS, in connection with and consideration for the Series B Purchase
Agreement, the Company seeks to extend certain registration and other rights to
the Series B Investors, pursuant to a Registration Rights Agreement to be
entered into by and among the Company and the Series B Investors (the
"Registration Rights Agreement"); and

         WHEREAS, the Company and the Series A Investors desire to amend the
Original Agreement to enable the Series B Investors to receive certain
registration and other rights under the Registration Rights Agreement which are
superior to those of the Series A Investors and to participate in certain other
rights with the Series A Investors; and

         WHEREAS, Sections 2.9 and 2.10 of the Original Agreement provide that
the Original Agreement may be amended or modified upon the written consent of
the Company and the holders of at least a majority of the Registrable Securities
Then Outstanding (for purposes of this First Amendment, the "Requisite Series A
Investor Shares"), and the Series A Investors hold the Requisite Series A
Investor Shares and desire to amend the Original Agreement.

                                       1

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                                                                Exhibit 10.17(A)

         IN CONSIDERATION of the foregoing and of the mutual promises, covenants
and agreement contained in this First Amendment, the parties, intending to be
legally bound, hereby agree as follows:

         1.       Amendment to Original Agreement.

         (a) Section 2.2.1 of the Original Agreement is hereby amended by adding
the following sentence to the end of such section:

                  "Notwithstanding the foregoing, no such request may be made,
                  and the Company shall not comply with the provisions of this
                  Section 2.2, unless at least ninety percent (90%) of the
                  Registrable Securities (as defined in the Registration Rights
                  Agreement) beneficially owned by the Initial Purchasers (as
                  defined in the Series B Purchase Agreement) have been sold by
                  the Initial Purchasers, either pursuant to an effective
                  registration statement under the Securities Act or pursuant to
                  Rule 144 under the Securities Act."

         (b) The parenthetical appearing in Section 2.3.1 of the Original
Agreement is hereby amended and restated in its entirety to read as follows:

                  "(including, but not limited to, registration statements
                  relating to secondary offerings of securities of the Company,
                  but excluding registration statements relating to employee
                  benefit plans, corporate reorganizations or other transactions
                  under Rule 145 of the Securities Act, or registrations not
                  involving an underwritten offering on Form S-3 effected
                  pursuant to Section 6 of the Registration Rights Agreement)"

         (c) Section 2.3.2 of the Original Agreement is hereby amended and
restated in its entirety to read as follows:

                  "2.3.2 UNDERWRITING. If the registration statement under which
                  the Company gives notice under this Section 2.3 is for an
                  underwritten offering, the Company shall so advise the
                  Holders. In such event, the right of any Holder to be included
                  in a registration pursuant to this Section 2.3 shall be
                  conditioned upon the Holder's participation in the
                  underwriting and, if such registration involves a required
                  registration effected by Series B Investors pursuant to
                  Section 4 or 6 of the Registration Rights Agreement (a "Series
                  B Demand"), the maximum number of shares to be registered on

                                       2

<PAGE>

                                                                Exhibit 10.17(A)

                  behalf of the Holders pursuant to the Series B Demand, as of
                  the date of the filing of the registration statement with the
                  Commission, shall be one-third of the aggregate number of
                  shares to be registered by all Holders and Series B Investors
                  participating in such Series B Demand, it being understood
                  that shares allocated to the Holders shall be allocated pro
                  rata among them based on the number of shares initially sought
                  to be registered by such Holder (or in such other manner as
                  the Holders otherwise agree). Notwithstanding any other
                  provision of the Agreement, if the underwriter determines in
                  good faith that marketing factors require a limitation of the
                  number of shares to be underwritten, and if such registration
                  is a Series B Demand, then the number of shares that may be
                  included in the underwriting shall be allocated among each of
                  the Series B Investors and each of the Holders pro rata based
                  on the total number of shares of Common Stock that each such
                  Holder and Series B Investor included in such registration
                  statement as initially filed with the Commission.
                  Notwithstanding any other provision of this Agreement, if the
                  underwriter determines in good faith that marketing factors
                  require a limitation of the number of shares to be
                  underwritten, and if such registration involves an offering
                  and sale of newly-issued securities by the Company, then the
                  number of shares that may be included in the underwriting
                  shall be allocated: first, to the Company; second, to the
                  Holders and the Series B Investors pro rata based on the total
                  number of shares of Common Stock that each of the Holders and
                  each of the Series B Investors sought to include in such
                  registration as reflected in the registration statement as
                  initially filed with the Commission (or in such other manner
                  as the Holders and the Series B Investors shall otherwise
                  agree); and, third, to any other stockholder of the Company
                  (other than a Holder or Series B Investor) pro rata based on
                  the total number of shares of Common Stock that each such
                  stockholder sought to include in such registration (or in such
                  other manner as such other stockholders shall otherwise
                  agree)."

         (d) Section 2.4.1 of the Original Agreement is hereby amended by adding
the following sentence to the end of such section:

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                                                                Exhibit 10.17(A)

                  "Notwithstanding the foregoing, no such request may be made,
                  and the Company shall not comply with the provisions of this
                  Section 2.4, unless at least ninety percent (90%) of the
                  Registrable Securities (as defined in the Series B Purchase
                  Agreement) beneficially owned by the Initial Purchasers (as
                  defined in the Series B Purchase Agreement) have been sold by
                  the Initial Purchasers, either pursuant to an effective
                  registration statement under the Securities Act or pursuant to
                  Rule 144 under the Securities Act."

         (e) Section 3.5 of the Original Amendment is hereby terminated and
shall have no further force or effect.

         (f) Section 4.1 of the Original Agreement is hereby amended and
restated in its entirety to read as follows:

                           "4.1 SUBSEQUENT OFFERINGS. In connection with
                  subsequent equity financings, the Investors shall have a right
                  of first refusal to purchase their pro rata share, which for
                  purposes of this Agreement shall mean the number securities
                  proposed to be issued by the Company multiplied by a fraction,
                  the numerator of which shall be the total number of shares of
                  Common Stock and any other security of the Company which by
                  its terms is convertible into or exchangeable or exercisable
                  for Common Stock (regardless of any vesting or other similar
                  restriction) then held by all Investors, and the denominator
                  of which shall be the total number of shares of Common Stock
                  and any other security of the Company which by its terms is
                  convertible into or exchangeable or exercisable for Common
                  Stock (regardless of any vesting or other similar restriction)
                  then outstanding, of all Equity Securities, as defined below,
                  that the Company may, from time to time, propose to sell and
                  issue after the date of this Agreement, other than the Equity
                  Securities excluded by Section 4.5 hereof. The term "Equity
                  Securities" shall mean (a) any Common Stock or Preferred Stock
                  of the Company, (b) any security convertible, with or without
                  consideration, into any Common Stock or Preferred Stock
                  (including any option to purchase such a convertible
                  security), (c) any security carrying any warrant or right to
                  subscribe to or purchase any Common Stock or Preferred Stock
                  or (d) any such warrant or right.

         2.       Further Effect of Original Agreement. Except as otherwise
amended herein, all other provisions of the Original Agreement shall remain in
full force and effect. The Original Agreement and this First Amendment shall be
construed together and considered one and the same agreement.

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                                                                Exhibit 10.17(A)

         3.       Counterparts. This First Amendment may be executed in
counterparts, each of which when executed shall be deemed to be an original, but
such counterparts shall together constitute one and the same instrument

         4.       Modifications to this Agreement. Sections 2.9 and 2.10 and
Section 5.5 of the Original Agreement (relating to amendments, modifications and
waivers) applies with equal force and effect to this First Amendment as if fully
set forth herein. Neither the Company nor any of the Series A Investors may
waive, amend, modify or supplement any of the provisions of the Original
Agreement which are amended by this First Amendment without the prior written
consent of (i) the Initial Purchasers holding at least sixty percent (60%) of
the Series B Preferred Stock (or the shares of Common Stock issued or issuable
upon conversion thereof) then held by all Initial Purchasers and (ii) a majority
of the then outstanding Conversion Shares; it being understood that the Initial
Purchasers and the holders of the Conversion Shares are intended beneficiaries
hereof.

                                       5

<PAGE>

                                                                Exhibit 10.17(A)

         IN WITNESS WHEREOF, the parties have executed this First Amendment to
Investor Rights Agreement on the date first above written.

COMPANY                                     SERIES A INVESTORS
Animas Corporation

By: /s/ Katherine D. Crothall
    ------------------------------          ------------------------------------

Name: /s/ Katherine D. Crothall
      ----------------------------          ------------------------------------

Its: President
                                            ------------------------------------

                                        6

<PAGE>

                                                                Exhibit 10.17(A)

         IN WITNESS WHEREOF, the parties have executed this First Amendment to
Investor Rights Agreement on the date first above written.

COMPANY                                  SERIES A INVESTORS
Animas Corporation

By:                                      Tennyson Fund II, LLLP
    -------------------------------

Name:                                    /s/ Alfred M. Walpert, Managing Partner
      -----------------------------      ---------------------------------------

Its:                                     Alfred M. Walpert
     ------------------------------

                                        7

<PAGE>

                                                                Exhibit 10.17(A)

         IN WITNESS WHEREOF, the parties have executed this First Amendment to
Investor Rights Agreement on the date first above written.

COMPANY                                     SERIES A INVESTORS
Animas Corporation

By:                                         /s/ William A. Graham IV
    -------------------------------         ------------------------------------

Name:                                       William A. Graham, IV
      -----------------------------

Its:                                        Attorney-In-Fact for:
    -------------------------------          William A. Graham, V

                                        8

<PAGE>

                                                                Exhibit 10.17(A)

         IN WITNESS WHEREOF, the parties have executed this First Amendment to
Investor Rights Agreement on the date first above written.

COMPANY                                     SERIES A INVESTORS
Animas Corporation

By:                                         /s/ William A. Graham IV
    -------------------------------         ------------------------------------

Name:                                       William A. Graham, IV
      -----------------------------

Its:                                        Attorney-In-Fact for:
    -------------------------------          Laura M. Graham

                                        9

<PAGE>

                                                                Exhibit 10.17(A)

         IN WITNESS WHEREOF, the parties have executed this First Amendment to
Investor Rights Agreement on the date first above written.

COMPANY                                     SERIES A INVESTORS
Animas Corporation

By:                                         /s/ William A. Graham IV
    -------------------------------         ------------------------------------

Name:                                       William A. Graham, IV
      -----------------------------

Its:
     ------------------------------         ------------------------------------

                                       10

<PAGE>

                                                                Exhibit 10.17(A)

         IN WITNESS WHEREOF, the parties have executed this First Amendment to
Investor Rights Agreement on the date first above written.

COMPANY                                     SERIES A INVESTORS
Animas Corporation

By:                                         /s/ Joe B. Byrum
    -------------------------------         ------------------------------------

Name:
      -----------------------------         ------------------------------------

Its:
    -------------------------------         ------------------------------------

                                       11

<PAGE>

                                                                Exhibit 10.17(A)

         IN WITNESS WHEREOF, the parties have executed this First Amendment to
Investor Rights Agreement on the date first above written.

COMPANY                                     SERIES A INVESTORS
Animas Corporation                           by FSIP LLC
By:                                         Anvers LP & Anvers II LP
    -------------------------------

Name:                                       /s/ L. Swergold
      -----------------------------         ------------------------------------

Its:                                        Sr. Managing Director
    -------------------------------

                                       12

<PAGE>

                                                                Exhibit 10.17(A)

         IN WITNESS WHEREOF, the parties have executed this First Amendment to
Investor Rights Agreement on the date first above written.

COMPANY                                     SERIES A INVESTORS
Animas Corporation

By:                                         /s/ Katherine D. Crothall
    -------------------------------         ------------------------------------

Name:
      -----------------------------         ------------------------------------

Its:
     ------------------------------         ------------------------------------

                                       13