Exhibit A.
JOINT FILING AGREEMENT
The undersigned hereby agree that the Statement on this Schedule 13D,
dated April 15, 2005 (the "Schedule 13D"), with respect to the Common Stock, par
value $.001 per share, of Acadia Pharmaceutical Inc. is filed on behalf of each
of us pursuant to and in accordance with the provisions of Rule 13d-1(k) under
the Securities and Exchange Act of 1934, as amended, and that this Agreement
shall be included as an Exhibit to this Schedule 13D. Each of the undersigned
agrees to be responsible for the timely filing of the Schedule 13D, and for the
completeness and accuracy of the information concerning itself contained
therein. This Agreement may be executed in any number of counterparts, all of
which taken together shall constitute one and the same instrument.
IN WITNESS WHEREOF, the undersigned have executed this Agreement as of
the 29th day of April 2005.
OrbiMed Advisors LLC
By: /s/ Xxxxxx X. Xxxxx
---------------------------
Name: Xxxxxx X. Xxxxx
Title: Managing Partner
OrbiMed Capital LLC
By: /s/ Xxxxxx X. Xxxxx
----------------------------
Name: Xxxxxx X. Xxxxx
Title: Managing Partner
By: /s/ Xxxxxx X. Xxxxx
----------------------------
Name: Xxxxxx X. Xxxxx
A-1
