ZP LETTERHEAD]

Exhibit 10.28

[ZP LETTERHEAD]

July 15, 2013

Xxxxxxxxx X. Xxxxxxxxxxxx, Ph.D.

c/o Regulus Therapeutics

0000 Xxxx Xxxxxxx Xx., Xxxxx 000

San Diego, CA 92121-1121

Re: Modification to Consulting Agreement

Dear Xxxxxxxxx:

This letter agreement (this “Amendment”) amends certain provisions of your Independent Director Agreement with ZP Holdings, Inc. (the “Company”) dated as of March 28, 2013 (the “Original Agreement”).

Per your request, beginning on the Company’s next scheduled pay date, all payments of the consulting fee and out-of-pocket expenses under the Original Agreement will be made to “Helios Capital, Inc.,” a California corporation controlled by you and located at 0000 Xx Xxxxxx Xxx Xxxxxx, Xx Xxxxx, Xxxxxxxxxx 00000. Accordingly, your Original Agreement is hereby amended such that each occurrence of the word “Director” in Section 2(i) and Section 2(iii) of the Original Agreement, Section 2(a) of Schedule A to the Original Agreement, and the first sentence of Section 2(c) of Schedule A to the Original Agreement shall be deleted and replaced with the words “Director or his designee.”

Except as expressly amended by this Amendment, the Original Agreement remains in full force and affect and otherwise unchanged. The Original Agreement shall, together with this Amendment, be read and construed as a single document. Please indicate your agreement to the Amendment by signing below and returning a copy of this letter to the Company at your earliest convenience.

Very truly yours,
ZP HOLDINGS, INC.
By:		/s/ Xxxxxx Xxxxx
		Xxxxxx Xxxxx
		President and Chief Executive Officer

Acknowledged and agreed by:

/s/ Xxxxxxxxx X. Xxxxxxxxxxxx

Xxxxxxxxx X. Xxxxxxxxxxxx