Joint Filer Information

Names:	Deerfield Mgmt, L.P., Deerfield Management Company, L.P., Deerfield Special Situations Fund, L.P., Deerfield Partners, L.P., Deerfield International Master Fund, L.P., Deerfield Private Design Fund II, L.P., Deerfield Private Design International II, L.P.

Address:	780 Third Avenue, 37th Floor New York, NY 10017

Designated Filer:	James E. Flynn

Issuer and Ticker Symbol:	Auspex Pharmaceuticals, Inc. [ASPX]

Date of Earliest Transaction Reported:	May 5, 2015

The undersigned, Deerfield Mgmt, L.P., Deerfield Management Company, L.P., Deerfield Special Situations Fund, L.P., Deerfield Partners, L.P., Deerfield International Master Fund, L.P., Deerfield Private Design Fund II, L.P. and Deerfield Private Design International II, L.P. are jointly filing the attached Statement of Changes in Beneficial Ownership on Form 4 with James E. Flynn with respect to the beneficial ownership of securities of Auspex Pharmaceuticals, Inc.

Signatures:

DEERFIELD MGMT, L.P.

By: J.E. Flynn Capital, LLC, General Partner

By: /s/ Jonathan Isler

Auspex Pharmaceuticals, Inc. 4