Exhibit 1
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Joint Filing Agreement
The undersigned hereby agree that the statement on Schedule 13D filed by
the undersigned with respect to the Common Stock of Neurogen Corporation is, and
any amendment thereto signed by each of the undersigned shall be, filed on
behalf of each undersigned pursuant to and in accordance with the provisions of
Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended.
Dated: April 21, 2004 WARBURG PINCUS PRIVATE EQUITY VIII, L.P.
By: Warburg Pincus & Co.,
General Partner
By: /s/ Xxxxx X. Xxxxxxx
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Name: Xxxxx X. Xxxxxxx
Title: Partner
Dated: April 21, 2004 WARBURG PINCUS & CO.
By: /s/ Xxxxx X. Xxxxxxx
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Name: Xxxxx X. Xxxxxxx
Title: Partner
Dated: April 21, 2004 WARBURG PINCUS LLC
By: /s/ Xxxxx X. Xxxxxxx
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Name: Xxxxx X. Xxxxxxx
Title: Managing Director
