Auspex Pharmaceuticals Form 4 Auspex Pharmaceuticals / James E Flynn ownership change

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

        Jonathan Isler, Attorney-In-Fact

DEERFIELD MANAGEMENT COMPANY, L.P.

By:  Flynn Management LLC, General Partner

By: /s/ Jonathan Isler

        Jonathan Isler, Attorney-In-Fact

DEERFIELD SPECIAL SITUATIONS FUND, L.P.

By:  Deerfield Mgmt, L.P., General Partner

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

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

DEERFIELD PARTNERS, L.P.

By:  Deerfield Mgmt, L.P., General Partner

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

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

DEERFIELD INTERNATIONAL MASTER FUND, L.P.

By:  Deerfield Mgmt, L.P., General Partner

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

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

DEERFIELD PRIVATE DESIGN FUND II, L.P.

By:  Deerfield Mgmt, L.P., General Partner

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

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

DEERFIELD PRIVATE DESIGN INTERNATIONAL II, L.P.

By:  Deerfield Mgmt, L.P., General Partner

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

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact