<PAGE>   1
                                                                Exhibit 10.67

                              CONNETICS CORPORATION
                          REGISTRATION RIGHTS AGREEMENT


       This Registration Rights Agreement (the "Agreement") is made as of the
11th day of January, 1999, by and among Connetics Corporation, a Delaware
corporation (the "Company") and Medeva, PLC ("Investor").


                                 R E C I T A L S

       A. Effective as of the same date as this Agreement, the Company and the
Investor have entered into a Common Stock Purchase Agreement (the "Purchase
Agreement") of even date herewith pursuant to which the Company has agreed to
sell to the Investor and the Investor has agreed to purchase from the Company
shares of the Company's Common Stock (all terms not otherwise defined herein
shall have the meanings ascribed in the Purchase Agreement).

       B. A condition to the Investor's obligations under the Purchase Agreement
is that the Company and the Investor enter into this Agreement in order to
provide the Investor with certain rights to register the Common Stock acquired
by the Investor pursuant to the Purchase Agreement. The Company desires to
induce the Investor to purchase the Common Stock pursuant to the Purchase
Agreement by agreeing to the terms and conditions set forth in this Agreement.

       NOW, THEREFORE, the parties hereby agree as follows:


                                    AGREEMENT

        1. Registration Rights. The Company and the Investor covenant and agree
as follows:

           1.1 Definitions. For purposes of this Section 1:

               (a) The terms "register," "registered," and "registration" refer
to a registration effected by preparing and filing a registration statement or
similar document in compliance with the Securities Act of 1933, as amended (the
"Securities Act"), and the declaration or ordering of effectiveness of such
registration statement or document;

               (b) The term "Registrable Securities" means (i) the shares of
Common Stock issued or sold in connection with the Purchase Agreement (such
shares of Common Stock are collectively referred to as the "Shares" or "Stock")
and (ii) any other shares of common stock of the Company issued as (or issuable
upon the conversion or exercise of any warrant, right or other security which is
issued as) a dividend or other distribution with respect to, or in exchange for
or in replacement of, the Stock; provided, that the foregoing definition shall
exclude in all cases any Registrable Securities sold by a person in a
transaction in which his or her rights under this Agreement are not assigned.
Notwithstanding the foregoing, shares of common stock shall only be treated as
Registrable Securities if and so long as they have not been (x) sold to or
through a broker or dealer or underwriter in a public distribution or a public
securities





                                                                          PAGE 1
<PAGE>   2

transaction, or (y) sold in a transaction exempt from the registration and
prospectus delivery requirements under Section 4(1) of the Securities Act so
that all transfer restrictions, and restrictive legends with respect thereto, if
any, are removed upon the consummation of such sale;

               (c) The number of shares of "Registrable Securities then
outstanding" shall be determined by the number of shares of Common Stock then
outstanding which are Registrable Securities, plus the number of shares of
common stock issuable pursuant to then exercisable or convertible securities
which are Registrable Securities;

               (d) The term "Holder" means any person owning or having the right
to acquire Registrable Securities or any assignee thereof in accordance with
this Agreement;

               (e) The term "Form S-3" means such form under the Securities Act
as in effect on the date hereof or any successor form under the Securities Act;
and

               (f) The term "SEC" means the Securities and Exchange Commission.

               (g) The term "Registration Expenses" shall mean all expenses,
except as otherwise stated below, incurred by the Company in complying with
Section 1.2 hereof, including, without limitation, all registration,
qualification and filing fees, printing expenses, escrow fees, fees and
disbursements of counsel for the Company and special counsel to the Selling
Holders, blue sky fees and expenses, the expense of any special audits incident
to or required by any such registration (but excluding the compensation of
regular employees of the Company which shall be paid in any event by the
Company).

               (h) The term "Selling Expenses" shall mean all underwriting
discounts, selling commissions and stock transfer taxes applicable to the
securities registered by the Holders.


           1.2 Registration

               (a) Notice of Registration. If at any time or from time to time
the Company shall determine to register any of its securities, either for its
own account or the account of a security holder or holders, other than (i) a
registration relating solely to employee benefit plans or (ii) a registration
relating solely to a Commission Rule 145 transaction, the Company will:

                   (i) promptly give to each Holder written notice thereof; and

                   (ii) include in such registration (and any related
qualification under blue sky laws or other compliance), and in any underwriting
involved therein, all the Registrable Securities specified in a written request
or requests, made within 20 days after receipt of such written notice from the
Company, by any Holder.





                                                                          PAGE 2
<PAGE>   3

               (b) Underwriting. If the registration of which the Company gives
notice is for a registered public offering involving an underwriting, the
Company shall so advise the Holders as a part of the written notice given
pursuant to Section 1.2(a)(i). In such event the right of any Holder to
registration pursuant to Section 1.2 shall be conditioned upon such Holder's
participation in such underwriting and the inclusion of such Holder's
Registrable Securities in the underwriting to the extent requested shall be
limited to the extent provided herein. All Holders proposing to distribute their
securities through such underwriting shall (together with the Company) enter
into an underwriting agreement in customary form with the managing underwriter
selected for such underwriting by the Company. Notwithstanding any other
provision of this Section 1.2, if the managing underwriter determines that
marketing factors require a limitation of the number of shares to be
underwritten, the managing underwriter may limit the Registrable Securities to
be distributed through such underwriting and if so limited, such Registrable
Securities shall be excluded from such underwriting and registration. The
Company shall so advise all Holders distributing their securities through such
underwriting of such limitation and the number of shares of Registrable
Securities that may be included in the registration and underwriting shall be
allocated among all Holders in proportion, as nearly as practicable, to the
respective amounts of Registrable Securities requested by such Holders to be
included in such registration statement. To facilitate the allocation of shares
in accordance with the above provisions, the Company may round the number of
shares allocated to any Holder or holder to the nearest 100 shares. If any
Holder or holder disapproves of the terms of any such underwriting, such Holder
or holder may elect to withdraw therefrom by written notice to the Company and
the managing underwriter. Any securities excluded or withdrawn from such
underwriting shall be withdrawn from such registration, and shall not be
transferred in a public distribution prior to 90 days after the effective date
of the registration statement relating thereto, or such other shorter period of
time as the underwriters may require.

               (c) Right to Terminate Registration. The Company shall have the
right to terminate or withdraw any registration initiated by it under this
Section 1.2 prior to the effectiveness of such registration whether or not any
Holder has elected to include securities in such registration. The Registration
Expenses of such withdrawn registration shall be borne by the Company in
accordance with Section 1.3 hereof.

           1.3 Expenses of Registration. All Registration Expenses incurred in
connection with registrations pursuant to Section 1.2 shall be borne by the
Company. All Selling Expenses relating to securities registered on behalf of the
Holders shall be borne by the Holders of securities included in such
registration pro rata with the Company and among each other on the basis of the
number of shares so registered.

           1.4. Registration Procedures. In the case of each registration,
qualification or compliance effected by the Company pursuant to this Section 1,
the Company will keep each Holder advised in writing as to the initiation of
each registration, qualification and compliance and as to the completion
thereof. At its expense the Company will:

               (a) Prepare and file with the Commission a registration statement
with respect to such securities and use its best efforts to cause such
registration





                                                                          PAGE 3
<PAGE>   4

statement to become and remain effective for at least thirty (30) days or until
the distribution described in the registration statement has been completed;

               (b) Prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
with such registration statement as may be necessary to comply with the
provisions of the Securities Act with respect to the disposition of all
securities covered by such registration statement;

               (c) Furnish to the Holders participating in such registration and
to the underwriters of the securities being registered such reasonable number of
copies of the registration statement, preliminary prospectus, final prospectus
and such other documents as such underwriters may reasonably request in order to
facilitate the public offering of such securities;

               (d) Furnish, at the request of any Holder requesting registration
of Registrable Securities at the time such securities are delivered to the
underwriters (if any) for sale in connection with a registration pursuant to
this Section 1.4, (i) an opinion, dated such date, of the counsel representing
the Company for the purposes of such registration, in form and substance as is
customarily given to underwriters in an underwritten public offering, addressed
to the underwriters, if any, and to the Holders requesting registration of
Registrable Securities.

               (e) Representations of Holders. Each Holder hereby represents to
and covenants with the Company that, during the period in which a registration
statement effected pursuant to Section 1.2 remains effective, such Holder will:

                   (i) not engage in any stabilization activity in connection
with any of the Company's securities;

                   (ii) cause to be furnished to any purchaser of the Shares and
to the broker-dealer, if any, through whom Shares may be offered, a copy of the
Prospectus; and

                   (iii) not bid for or purchase any securities of the Company
or any rights to acquire the Company's securities, or attempt to induce any
person to purchase any of the Company's securities or any rights to acquire the
Company's securities other than as permitted under the Securities Exchange Act
of 1934, as amended ("Exchange Act").

           1.5 Furnish Information. It shall be a condition precedent to the
obligations of the Company to take any action pursuant to this Section 1 with
respect to the Registrable Securities of any selling Holder that such Holder
shall furnish to the Company such information regarding itself, the Registrable
Securities held by it, and the intended method of disposition of such securities
as shall be required to effect the registration of such Holder's Registrable
Securities.





                                                                          PAGE 4
<PAGE>   5

           1.6 Delay of Registration. No Holder shall have any right to obtain
or seek an injunction restraining or otherwise delaying any such registration as
the result of any dispute that might arise with respect to the interpretation or
implementation of this Section 1.

           1.7 Indemnification. In the event any Registrable Securities are
included in a registration statement under this Section 1:

               (a) To the extent permitted by law, the Company will indemnify
and hold harmless each Holder, any underwriter (as defined in the Securities)
for such Holder and each person, if any, who controls such Holder or underwriter
within the meaning of the Securities or the Exchange Act, against any losses,
claims, damages, or liabilities (joint or several) to which they may become
subject under the Securities, the Exchange Act or other federal or state law,
insofar as such losses, claims, damages, or liabilities (or actions in respect
thereof) arise out of or are based upon any of the following statements,
omissions or violations (collectively a "Violation"): (i) any untrue statement
or alleged untrue statement of a material fact contained in such registration
statement, including any preliminary prospectus or final prospectus contained
therein or any amendments or supplements thereto, (ii) the omission or alleged
omission to state therein a material fact required to be stated therein, or
necessary to make the statements therein not misleading, or (iii) any violation
or alleged violation by the Company of the Securities, the Exchange Act, any
state securities law or any rule or regulation promulgated under the Securities,
the Exchange Act or any state securities law; and the Company will pay to each
such Holder, underwriter or controlling person, as incurred, any legal or other
expenses reasonably incurred by them in connection with investigating or
defending any such loss, claim, damage, liability, or action; provided, however,
that the indemnity agreement contained in this subsection 1.7(a) shall not apply
to amounts paid in settlement of any such loss, claim, damage, liability, or
action if such settlement is effected without the consent of the Company (which
consent shall not be unreasonably withheld), nor shall the Company be liable in
any such case for any such loss, claim, damage, liability, or action to the
extent that it arises out of or is based upon a Violation which occurs in
reliance upon and in conformity with written information furnished expressly for
use in connection with such registration by any such Holder, underwriter or
controlling person.

               (b) To the extent permitted by law, each selling Holder will
indemnify and hold harmless the Company, each of its directors, each of its
officers who has signed the registration statement, each person, if any, who
controls the Company within the meaning of the Securities, any underwriter, any
other Holder selling securities in such registration statement and any
controlling person of any such underwriter or other Holder, against any losses,
claims, damages, or liabilities (joint or several) to which any of the foregoing
persons may become subject, under the Securities, the Exchange Act or other
federal or state law, insofar as such losses, claims, damages, or liabilities
(or actions in respect thereto) arise out of or are based upon any Violation, in
each case to the extent (and only to the extent) that such Violation occurs in
reliance upon and in conformity with written information furnished by such
Holder expressly for use in connection with such registration; and each such
Holder will pay, as incurred, any legal or other expenses reasonably incurred by
any person intended to be indemnified pursuant to this subsection 1.7(b), in
connection with investigating or defending any such loss, claim, damage,
liability, or action; provided, however, that the indemnity agreement contained
in this subsection 1.7(b) shall not apply to amounts paid in settlement of any
such loss, claim, damage, liability or





                                                                          PAGE 5
<PAGE>   6

action if such settlement is effected without the consent of the Holder, which
consent shall not be unreasonably withheld; provided, that, in no event shall
any indemnity under this subsection 1.7(b) exceed the net proceeds from the
offering received by such Holder, except in the case of willful fraud by such
Holder.

               (c) Promptly after receipt by an indemnified party under this
Section 1.7 of notice of the commencement of any action (including any
governmental action), such indemnified party will, if a claim in respect thereof
is to be made against any indemnifying party under this Section 1.7, deliver to
the indemnifying party a written notice of the commencement thereof and the
indemnifying party shall have the right to participate in, and, to the extent
the indemnifying party so desires, jointly with any other indemnifying party
similarly noticed, to assume the defense thereof with counsel mutually
satisfactory to the parties; provided, however, that an indemnified party
(together with all other indemnified parties which may be represented without
conflict by one counsel) shall have the right to retain one separate counsel,
with the reasonable fees and expenses to be paid by the indemnifying party, if
representation of such indemnified party by the counsel retained by the
indemnifying party would be inappropriate due to actual or potential differing
interests between such indemnified party and any other party represented by such
counsel in such proceeding. The failure to deliver written notice to the
indemnifying party within a reasonable time of the commencement of any such
action, if prejudicial to its ability to defend such action, shall relieve such
indemnifying party of any liability to the indemnified party under this Section
1.7, but the omission so to deliver written notice to the indemnifying party
will not relieve it of any liability that it may have to any indemnified party
otherwise than under this Section 1.7.

               (d) If the indemnification provided for in this Section 1.7 is
held by a court of competent jurisdiction to be unavailable to an indemnified
party with respect to any loss, liability, claim, damage, or expense referred to
therein, then the indemnifying party, in lieu of indemnifying such indemnified
party hereunder, shall contribute to the amount paid or payable by such
indemnified party as a result of such loss, liability, claim, damage, or expense
in such proportion as is appropriate to reflect the relative fault of the
indemnifying party on the one hand and of the indemnified party on the other in
connection with the statements or omissions that resulted in such loss,
liability, claim, damage, or expense as well as any other relevant equitable
considerations; provided that, in no event shall any contribution by a Holder
under this Subsection 1.7(d) exceed the net proceeds from the offering received
by such Holder, except in the case of willful fraud by such Holder. The relative
fault of the indemnifying party and of the indemnified party shall be determined
by reference to, among other things, whether the untrue or alleged untrue
statement of a material fact or the omission to state a material fact relates to
information supplied by the indemnifying party or by the indemnified party and
the parties' relative intent, knowledge, access to information, and opportunity
to correct or prevent such statement or omission.

               (e) The obligations of the Company and Holders under this Section
1.7 shall survive the completion of any offering of Registrable Securities in a
registration statement under this Section 1.





                                                                          PAGE 6
<PAGE>   7

           1.8 Reports Under Securities Exchange Act Of 1934. With a view to
making available to the Holders the benefits of Rule 144 and any other rule or
regulation of the SEC that may at any time permit a Holder to sell securities of
the Company to the public without registration or pursuant to a registration on
Form S-3, the Company agrees to:

               (a) make and keep public information available, as those terms
are understood and defined in Rule 144, so long as the Company remains subject
to the periodic reporting requirements under Sections 13 or 15(d) of the
Exchange Act;

               (b) take such action, including the voluntary registration of its
Common Stock under Section 12 of the Exchange Act, as is necessary to enable the
Holders to utilize Form S-3 for the sale of their Registrable Securities;

               (c) file with the SEC in a timely manner all reports and other
documents required of the Company under the Securities and the Exchange Act; and

               (d) furnish to any Holder, so long as the Holder owns any
Registrable Securities, forthwith upon request (i) a written statement by the
Company that it has complied with the reporting requirements of the Exchange Act
and the rules and regulations promulgated thereunder, or that it qualifies as a
registrant whose securities may be resold pursuant to Form S-3, (ii) a copy of
the most recent annual or quarterly report of the Company and such other reports
and documents so filed by the Company, and (iii) such other information as may
be reasonably requested in availing any Holder of any rule or regulation of the
SEC which permits the selling of any such securities without registration or
pursuant to such form.

           1.9 Termination of Registration Rights. The rights granted under this
Section 1 shall terminate on the second anniversary of the effective date of
this Agreement.

        2. MISCELLANEOUS.

           2.1 Successors and Assigns. Except as otherwise provided in this
Agreement, the terms and conditions of this Agreement shall inure to the benefit
of and be binding upon the respective successors and assigns of the parties
(including transferees of any of the Shares). Nothing in this Agreement, express
or implied, is intended to confer upon any party other than the parties hereto
or their respective successors and assigns any rights, remedies, obligations, or
liabilities under or by reason of this Agreement, except as expressly provided
in this Agreement.

           2.2 Governing Law. This Agreement and all acts and transactions
pursuant hereto shall be governed, construed and interpreted in accordance with
the laws of the State of California, without giving effect to principles of
conflicts of laws.

           2.3 Counterparts. This Agreement may be executed in two (2) or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.





                                                                          PAGE 7
<PAGE>   8

           2.4 Titles and Subtitles. The titles and subtitles used in this
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement.

           2.5 Notices. Unless otherwise provided herein, any notice required or
permitted by this Agreement shall be in writing and shall be deemed sufficient
upon delivery, when delivered personally or by overnight courier and addressed
to the party to be notified at such party's address as set forth on the
signature page hereto or as subsequently modified by written notice. In the
event that any date provided for in this Agreement falls on a Saturday, Sunday
or legal holiday, such date shall be deemed extended to the next business day.
Notwithstanding the foregoing, any notice delivered pursuant to Section 1.6
hereto must be made by personal delivery or confirmed facsimile transmission.

           2.6 Expenses. If any action at law or in equity is necessary to
enforce or interpret the terms of this Agreement, the prevailing party shall be
entitled to reasonable attorneys' fees, costs and necessary disbursements in
addition to any other relief to which such party may be entitled.

           2.7 Amendments and Waivers. Any term of this Agreement may be amended
and the observance of any term of this Agreement may be waived (either generally
or in a particular instance and either retroactively or prospectively), only
with the written consent of the Company and the holders of a majority of the
Registrable Securities then outstanding. Any amendment or waiver effected in
accordance with this paragraph shall be binding upon each holder of any
Registrable Securities then outstanding, each future holder of all such
Registrable Securities, and the Company.

           2.8 Severability. If one or more provisions of this Agreement are
held to be unenforceable under applicable law, the parties agree to renegotiate
such provision in good faith. In the event that the parties cannot reach a
mutually agreeable and enforceable replacement for such provision, then (a) such
provision shall be excluded from this Agreement, (b) the balance of the
Agreement shall be interpreted as if such provision were so excluded and (c) the
balance of the Agreement shall be enforceable in accordance with its terms.

           2.9 Entire Agreement. This Agreement, and the documents referred to
in this Agreement (with the exception of the registration statement) constitute
the entire agreement between the parties hereto pertaining to the subject matter
hereof, and any and all other written or oral agreements existing between the
parties hereto are expressly canceled.






                                                                          PAGE 8
<PAGE>   9


IN WITNESS WHEREOF, the parties have executed this Registration Rights Agreement
as of the date first written above.



                                                 COMPANY

Connetics Corporation                            Address:

                                                 3400 West Bayshore Road
                                                 Palo Alto, California 94303
By:   /s/ Thomas G. Wiggans                      Facsimile:  (650) 843-2899
    ---------------------------------------
      Thomas G. Wiggans
      President and Chief Executive Officer



                                                 INVESTOR

Medeva, PLC                                      Address:

                                                 10 St. James's Street
                                                 London SW1A 1EF
                                                 United Kingdom
                                                 Facsimile: 011-44-171-930-7909
By:   /s/ Garry Watts
   ---------------------------------------- 
      Garry Watts
      Its Duly Authorized Officer





















                                                                          PAGE 9