<SEC-DOCUMENT>0001193125-15-244346.txt : 20150702
<SEC-HEADER>0001193125-15-244346.hdr.sgml : 20150702
<ACCEPTANCE-DATETIME>20150702163209
ACCESSION NUMBER:		0001193125-15-244346
CONFORMED SUBMISSION TYPE:	S-8
PUBLIC DOCUMENT COUNT:		3
FILED AS OF DATE:		20150702
DATE AS OF CHANGE:		20150702
EFFECTIVENESS DATE:		20150702

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Amphastar Pharmaceuticals, Inc.
		CENTRAL INDEX KEY:			0001297184
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				330702205
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		S-8
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-205470
		FILM NUMBER:		15970209

	BUSINESS ADDRESS:	
		STREET 1:		11570 SIXTH STREET
		CITY:			RANCHO CUCAMONGA
		STATE:			CA
		ZIP:			91730
		BUSINESS PHONE:		909-980-9484

	MAIL ADDRESS:	
		STREET 1:		11570 SIXTH STREET
		CITY:			RANCHO CUCAMONGA
		STATE:			CA
		ZIP:			91730
</SEC-HEADER>
<DOCUMENT>
<TYPE>S-8
<SEQUENCE>1
<FILENAME>d949153ds8.htm
<DESCRIPTION>FORM S-8
<TEXT>
<HTML><HEAD>
<TITLE>Form S-8</TITLE>
</HEAD>
 <BODY BGCOLOR="WHITE">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>As filed with the Securities and Exchange Commission on July&nbsp;2, 2015 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>Registration No.&nbsp;333-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </B></P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES
AND EXCHANGE COMMISSION </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Washington, D.C. 20549 </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>FORM S-8 </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>REGISTRATION
STATEMENT </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>UNDER </I></B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>THE SECURITIES ACT OF 1933 </I></B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:24pt; font-family:Times New Roman" ALIGN="center"><B>AMPHASTAR
PHARMACEUTICALS, INC. </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Exact name of Registrant as specified in its charter) </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:8pt" ALIGN="center">


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<TD WIDTH="48%"></TD></TR>


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<TD VALIGN="top" ALIGN="center"><B>Delaware</B></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top" ALIGN="center"><B>33-0702205</B></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:8pt">
<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(State or other jurisdiction of</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>incorporation or organization)</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(I.R.S. Employer</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Identification Number)</B></P></TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>11570 6th Street </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Rancho Cucamonga, California 91730 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Address, including Zip Code, of Principal Executive Offices) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>2015 Equity Incentive Plan </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Full title of the plan) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Jason B. Shandell </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>President </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Amphastar
Pharmaceuticals, Inc. </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>11570 6th Street </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Rancho Cucamonga, California 91730 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(909) 980-9484 </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Name,
address and telephone number, including area code, of agent for service) </B></P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B></B><B><I>Copies to:</I></B><B> </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


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<TD WIDTH="48%"></TD></TR>


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<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Donna M. Petkanics</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Andrew D. Hoffman</B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Wilson
Sonsini Goodrich&nbsp;&amp; Rosati, P.C.</B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>650 Page Mill Road</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Palo Alto, California 94304</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(650) 493-9300</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>William J. Peters</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Richard D. Whitlow</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Amphastar Pharmaceuticals, Inc.</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>11570 6th Street</B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Rancho
Cucamonga, California 91730</B></P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(909) 980-9484</B></P></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See
the definitions of &#147;large accelerated filer,&#148; &#147;accelerated filer&#148; and &#147;smaller reporting company&#148; in Rule 12b-2 of the Exchange Act. (Check one): </P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="16%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="59%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="20%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="1%"></TD></TR>


<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">Large&nbsp;accelerated&nbsp;filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">Accelerated&nbsp;filer</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">Non-accelerated filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT>&nbsp;&nbsp;(Do&nbsp;not&nbsp;check&nbsp;if&nbsp;a&nbsp;smaller&nbsp;reporting&nbsp;company)</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">Smaller&nbsp;reporting&nbsp;company</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>CALCULATION OF REGISTRATION FEE </B></P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:8pt" ALIGN="center">


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<TD WIDTH="44%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="13%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="13%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="13%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="13%"></TD></TR>


<TR STYLE="font-size:1px; ">
<TD COLSPAN="9" VALIGN="bottom"> <P STYLE="border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Title&nbsp;of Securities</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>to be Registered</B></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Amount</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>to be</B></P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Registered
(1)</B></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Proposed</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Maximum</B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Offering
Price</B></P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>per Share</B></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Proposed</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Maximum<BR>Aggregate</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Offering Price</B></P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Amount of</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Registration Fee</B></P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" STYLE="BORDER-TOP:1px solid #000000"> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Common Stock, par value $0.0001 per share, reserved for issuance pursuant to the 2015 Equity
Incentive Plan</P></TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">5,000,000(2)</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$17.54(3)</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$87,700,000(3)</TD>
<TD VALIGN="bottom" STYLE="BORDER-LEFT:1px solid #000000; BORDER-TOP:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="BORDER-TOP:1px solid #000000">$10,190.74(3)</TD></TR>
<TR STYLE="font-size:1px; ">
<TD COLSPAN="9" VALIGN="bottom"> <P STYLE="border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
<TR STYLE="font-size:1px; ">
<TD COLSPAN="9" VALIGN="bottom"> <P STYLE="border-top:1.00px solid #000000">&nbsp;</P></TD></TR>
</TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(1)</TD>
<TD ALIGN="left" VALIGN="top">Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the &#147;Securities Act&#148;), this registration statement shall also cover any additional shares of the Registrant&#146;s common stock that become
issuable pursuant to the Registrant&#146;s 2015 Equity Incentive Plan (the &#147;2015 Plan&#148;) by reason of any dividend or other distribution (whether in the form of cash, shares of the Registrant&#146;s common stock, other securities, or other
property), recapitalization, stock split, reorganization, merger, consolidation, split-up, spin-off, combination, repurchase, or exchange of shares of the Registrant&#146;s common stock or other securities of the Registrant, or other change in the
corporate structure of the Registrant affecting the shares of the Registrant&#146;s common stock. </TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(2)</TD>
<TD ALIGN="left" VALIGN="top">Represents 5,000,000 shares of common stock reserved for issuance pursuant to awards under the 2015 Plan. The shares of common stock subject to outstanding awards previously granted under the Registrant&#146;s Amended
and Restated 2002 Stock Option/Stock Issuance Plan, the Registrant&#146;s Amended and Restated 2005 Equity Incentive Award Plan, or any other equity incentive plans or arrangement of the Registrant (the &#147;Existing Plans&#148;) that expire or
terminate without having been exercised on or after March&nbsp;18, 2015 and the shares issued pursuant to awards granted under the Existing Plans that are forfeited or repurchased by the Registrant on or after March&nbsp;18, 2015 will be added to
the number of shares available for issuance under the 2015 Plan, subject to the limits in the next sentence. No more than 12,000,000 shares of common stock will be added to the 2015 Plan from the Existing Plans pursuant to the preceding sentence.
</TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">(3)</TD>
<TD ALIGN="left" VALIGN="top">Estimated in accordance with Rule 457(h) solely for purposes of calculating the registration fee on the basis of $17.54, the average of the high and low prices of Registrant&#146;s common stock as reported on the NASDAQ
Global Select Market on June&nbsp;29, 2015. </TD></TR></TABLE> <P STYLE="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>

<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>PART I </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>INFORMATION REQUIRED IN THE PROSPECTUS </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The documents containing the information specified in Item&nbsp;1 and Item&nbsp;2 of this Registration Statement will be sent or given to
employees, officers, directors or others as specified by Rule&nbsp;428(b)(1) under the Securities Act of 1933, as amended (the &#147;<B>Securities Act</B>&#148;). In accordance with the rules and regulations of the Securities and Exchange Commission
(the &#147;<B>Commission</B>&#148;) and the instructions to the Registration Statement, such documents are not being filed with the Commission either as part of this Registration Statement or as prospectuses or prospectus supplements pursuant to
Rule&nbsp;424. </P> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>PART II </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>INFORMATION REQUIRED IN THE REGISTRATION STATEMENT </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;3.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Incorporation of Documents by Reference. </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Amphastar Pharmaceuticals, Inc. (the
&#147;<B>Registrant</B>&#148;) hereby incorporates by reference in this Registration Statement the following documents and information previously filed with the Commission: </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">(1)</TD>
<TD ALIGN="left" VALIGN="top">The Registrant&#146;s Annual Report on Form 10-K for the fiscal year ended December&nbsp;31, 2014, filed with the Commission on March&nbsp;26, 2015 pursuant to Section 13(a) of the Securities Exchange Act of 1934, as
amended (the &#147;<B>Exchange Act</B>&#148;); </TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="8%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">(2)</TD>
<TD ALIGN="left" VALIGN="top">All other reports filed by the Registrant with the Commission pursuant to Sections 13(a) or 15(d) of the Exchange Act since the end of the fiscal year covered by the Registrant&#146;s Annual Report referred to in (1)
above; and </TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="8%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">(3)</TD>
<TD ALIGN="left" VALIGN="top">The description of the Registrant&#146;s common stock contained in the Registrant&#146;s Registration Statement on Form 8-A (File No.&nbsp;001-36509) filed with the Commission on June&nbsp;18, 2014, pursuant to
Section&nbsp;12(b) of the Exchange Act, including any amendment or report filed for the purpose of updating such description. </TD></TR></TABLE>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">All documents filed by the Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act on or after the date of this
Registration Statement and prior to the filing of a post-effective amendment to this Registration Statement that indicate that all securities offered have been sold or that deregisters all securities then remaining unsold shall be deemed to be
incorporated by reference in this Registration Statement and to be a part hereof from the date of filing of such documents; <I>provided</I>, <I>however</I>, that documents or information deemed to have been furnished and not filed in accordance with
the rules of the Commission shall not be deemed incorporated by reference into this Registration Statement. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Any statement contained in a
document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any other subsequently filed
document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this
Registration Statement. </P> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;4.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Description of Securities. </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Not applicable. </P>

<p Style='page-break-before:always'>
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<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;5.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Interests of Named Experts and Counsel. </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Not applicable. </P>
<P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;6.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Indemnification of Directors and Officers. </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Section&nbsp;102 of the General Corporation
Law of the State of Delaware permits a corporation to eliminate the personal liability of directors of a corporation to the corporation or its stockholders for monetary damages for a breach of fiduciary duty as a director, except for breaches of the
director&#146;s duty of loyalty to the corporation or its stockholders, acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of a law, authorizations of the payments of a dividend or approval of a stock
repurchase or redemption in violation of Delaware corporate law or for any transactions from which the director derived an improper personal benefit. The Registrant&#146;s amended and restated certificate of incorporation provides that no director
will be liable to the Registrant or its stockholders for monetary damages for breach of fiduciary duties as a director, subject to the same exceptions as described above. The Registrant has entered into separate indemnification agreements with each
of its directors which may, in some cases, be broader than the specific indemnification provisions contained under Delaware law.&nbsp;These indemnification agreements generally require the Registrant, among other things, to indemnify its directors
against liabilities that may arise by reason of their status or service as directors. These indemnification agreements also generally require the Registrant to advance any expenses incurred by the directors as a result of any proceeding against them
as to which they could be indemnified. The Registrant also has purchased and expects to maintain standard insurance policies that provide coverage (1)&nbsp;to its directors and officers against loss arising from claims made by reason of breach of
duty or other wrongful act and (2)&nbsp;to it with respect to indemnification payments it may make to such officers and directors. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Section&nbsp;145 of the General Corporation Law of the State of Delaware provides that a corporation has the power to indemnify a director,
officer, employee, or agent of the corporation and certain other persons serving at the request of the corporation in related capacities against expenses (including attorneys&#146; fees), judgments, fines and amounts paid in settlements actually and
reasonably incurred by the person in connection with a threatened, pending, or completed action, suit or proceeding to which he or she is or is threatened to be made a party by reason of such position, if such person acted in good faith and in a
manner he or she reasonably believed to be in or not opposed to the best interests of the corporation, and, in any criminal action or proceeding, had no reasonable cause to believe his or her conduct was unlawful, except that, in the case of actions
brought by or in the right of the corporation, indemnification is limited to expenses (including attorneys&#146; fees) actually and reasonably incurred by the person in connection with defense or settlement of such action or suit and no
indemnification shall be made with respect to any claim, issue, or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery or other adjudicating court
determines that, despite the adjudication of liability but in view of all of the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which the Court of Chancery or such other court shall deem
proper. In addition, to the extent that a present or former director or officer of a corporation has been successful on the merits or otherwise in defense of any action, suit, or proceeding described above (or claim, issue, or matter therein), such
person shall be indemnified against expenses (including attorneys&#146; fees) actually and reasonably incurred by such person in connection therewith. Expenses (including attorneys&#146; fees) incurred by an officer or director in defending any
civil, criminal, administrative, or investigative action, suit, or proceeding may be advanced by the corporation upon receipt of an undertaking by such person to repay such amount if it is ultimately determined that such person is not entitled to
indemnification by the corporation under Section&nbsp;145 of the General Corporation Law of the State of Delaware. </P>
 <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">2 </P>


<p Style='page-break-before:always'>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Registrant&#146;s amended and restated certificate of incorporation provide that it will, to
the fullest extent permitted by law, indemnify any person made or threatened to be made a party to an action or proceeding by reason of the fact that he or she (or his or her testators or intestate) is or was a director or officer of the Registrant
or serves or served at any other corporation, partnership, joint venture, trust or other enterprise in a similar capacity or as an employee or agent at the Registrant&#146;s request, including service with respect to employee benefit plans
maintained or sponsored by the Registrant, against expenses (including attorneys&#146;), judgments, fines, penalties and amounts paid in settlement incurred in connection with the investigation, preparation to defend, or defense of such action,
suit, proceeding, or claim. However, the Registrant is not required to indemnify or advance expenses in connection with any action, suit, proceeding, claim, or counterclaim initiated by it or on behalf of it. The Registrant&#146;s amended and
restated bylaws provide that it will indemnify and hold harmless each person who was or is a party or threatened to be made a party to any action, suit, or proceeding by reason of the fact that he or she is or was a director or officer of the
Registrant, or is or was serving at the Registrant&#146;s request in a similar capacity of another corporation, partnership, joint venture, trust or other enterprise, including service with respect to employee benefit plans (whether the basis of
such action, suit, or proceeding is an action in an official capacity as a director or officer or in any other capacity while serving as a director of officer) to the fullest extent authorized by the Delaware General Corporation Law against all
expense, liability and loss (including attorneys&#146; fees, judgments, fines, ERISA excise taxes, or penalties and amounts paid in settlement) reasonably incurred or suffered by such person in connection with such action, suit or proceeding, and
this indemnification continues after such person has ceased to be an officer or director and inures to the benefit of such person&#146;s heirs, executors and administrators. The indemnification rights also include the right generally to be advanced
expenses, subject to any undertaking required under Delaware General Corporation Law, and the right generally to recover expenses to enforce an indemnification claim or to defend specified suits with respect to advances of indemnification expenses.
</P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The indemnification rights set forth above are not exclusive of any other right which an indemnified person may have or hereafter acquire
under any statute, provision of the Registrant&#146;s amended and restated certificate of incorporation, the Registrant&#146;s amended and restated bylaws, agreement, vote of stockholders or disinterested directors, or otherwise. </P>
<P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;7.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Exemption from Registration Claimed. </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Not applicable. </P>
<P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;8.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Exhibits </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">See Exhibit Index immediately following the signature pages. </P>
<P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR>
<TD WIDTH="8%" VALIGN="top" ALIGN="left"><B>Item&nbsp;9.</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Undertakings. </B></TD></TR></TABLE> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">A. The undersigned Registrant hereby undertakes: </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:4%; text-indent:4%; font-size:10pt; font-family:Times New Roman">(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration
statement: </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; text-indent:4%; font-size:10pt; font-family:Times New Roman">(i) To include any prospectus required by Section&nbsp;10(a)(3) of the Securities Act of 1933; </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; text-indent:4%; font-size:10pt; font-family:Times New Roman">(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the
most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of
securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any </P>
 <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">3 </P>


<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; margin-left:8%; font-size:10pt; font-family:Times New Roman">
deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
changes in volume and price represent no more than a 20 percent change in the maximum aggregate offering price set forth in the &#147;Calculation of Registration Fee&#148; table in the effective registration statement; </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:8%; text-indent:4%; font-size:10pt; font-family:Times New Roman">(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration
statement or any material change to such information in the registration statement. </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:4%; text-indent:4%; font-size:10pt; font-family:Times New Roman"><I>Provided, however</I>, that
paragraphs (A)(1)(i) and (A)(1)(ii) do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the Registrant pursuant to
Section&nbsp;13 or Section&nbsp;15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in this registration statement. </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:4%; text-indent:4%; font-size:10pt; font-family:Times New Roman">(2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment
shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial <I>bona fide</I> offering thereof. </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; margin-left:4%; text-indent:4%; font-size:10pt; font-family:Times New Roman">(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain
unsold at the termination of the offering. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">B. The undersigned Registrant hereby undertakes that, for purposes of determining any
liability under the Securities Act of 1933, each filing of the Registrant&#146;s annual report pursuant to Section&nbsp;13(a) or Section&nbsp;15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit
plan&#146;s annual report pursuant to Section&nbsp;15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered
therein, and the offering of such securities at that time shall be deemed to be the initial <I>bona fide</I> offering thereof. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">C. Insofar
as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in
the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the
payment by the Registrant of expenses incurred or paid by a director, officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification
by it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue. </P>
 <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">4 </P>


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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>SIGNATURES </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:8%; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Act, the Registrant certifies that it has reasonable grounds to believe that it meets all of
the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of Rancho Cucamonga, State of California, on this 2<SUP
STYLE="font-size:85%; vertical-align:top">nd</SUP> day of July, 2015. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><DIV ALIGN="right">
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<TR>
<TD WIDTH="6%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="92%"></TD></TR>


<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="3"><B>Amphastar Pharmaceuticals, Inc.</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Jason B. Shandell</P></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">Jason B. Shandell</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">President</TD></TR>
</TABLE></DIV> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>POWER OF ATTORNEY </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:8%; font-size:10pt; font-family:Times New Roman"><I>KNOW ALL PERSONS BY THESE PRESENTS</I>, that each person whose signature appears below hereby constitutes and appoints Jack Yongfeng Zhang,
Jason B. Shandell and William J. Peters, and each of them, as their true and lawful attorney-in-fact and agent with full power of substitution, for him or her in any and all capacities, to sign any and all amendments to this Registration Statement
and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorney-in-fact, proxy and agent full power and authority to do and perform each and every
act and thing requisite and necessary to be done in connection therewith, as fully for all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorney-in-fact, proxy and agent, or his or her
substitute, may lawfully do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act, this registration statement and the Power of Attorney has been signed by the following persons in the capacities and on the dates
indicated. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="37%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="44%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="15%"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="border-bottom:1.00pt solid #000000; width:33.30pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Signature</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="border-bottom:1.00pt solid #000000; width:15.95pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Title</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="border-bottom:1.00pt solid #000000; width:16.00pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Date</B></P></TD></TR>


<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Jack Yongfeng Zhang</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Jack Yongfeng Zhang</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Chief Executive Officer and Director</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">(Principal
Executive Officer)</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>July 2, 2015</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Mary Z. Luo</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Mary Z. Luo</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Chairman, Chief Operating Officer and</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Director</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>July 2, 2015</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ William J. Peters</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">William J. Peters</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Chief Financial Officer (Principal Financial</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Officer and Principal Accounting Officer)</P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>July 2, 2015</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Jason B. Shandell</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Jason B. Shandell</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">President and Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>July 2, 2015</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Richard Koo</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Richard Koo</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>July 2, 2015</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Howard Lee</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Howard Lee</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>July 2, 2015</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Floyd Petersen</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Floyd Petersen</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>July 2, 2015</TD></TR>
</TABLE>
 <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">5 </P>


<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">

<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


<TR>
<TD WIDTH="37%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="44%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="15%"></TD></TR>


<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Richard Prins</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Richard Prins</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">July&nbsp;2, 2015</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Stephen Shohet</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Stephen Shohet</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">July 2, 2015</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Michael A. Zasloff</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Michael A. Zasloff</P></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="top">July 2, 2015</TD></TR>
</TABLE>
 <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">6 </P>


<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>EXHIBIT INDEX </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>
<TD WIDTH="5%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="63%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="5%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="8%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="4%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="9%"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" COLSPAN="5" ALIGN="center"><B>Incorporated by Reference Herein</B></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ALIGN="center"><B>Exhibit<BR>Number</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Description</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Filed<BR>Herewith</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Form</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Exhibit</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Filing&nbsp;Date</B></TD></TR>


<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;4.1</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Specimen Common Stock certificate of the Registrant</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP>Form&nbsp;S-1/A</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center">4.1</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP>June&nbsp;5,&nbsp;2014</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;4.2</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">2015 Equity Incentive Plan and forms of agreement thereunder</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP>Form 8-K</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center">10.1</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP>June&nbsp;1,&nbsp;2015</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">&nbsp;&nbsp;5.1</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Opinion of Wilson Sonsini Goodrich &amp; Rosati, Professional Corporation</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center">X</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">23.1</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Consent of Independent Registered Public Accounting Firm</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center">X</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">23.2</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Consent of Wilson Sonsini Goodrich &amp; Rosati, Professional Corporation (contained in Exhibit 5.1 hereto)</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center">X</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP> <P STYLE="margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">24.1</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Power of Attorney (contained on signature pages hereto)</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP ALIGN="center">X</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD></TR>
</TABLE>
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</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>d949153dex51.htm
<DESCRIPTION>EX-5.1
<TEXT>
<HTML><HEAD>
<TITLE>EX-5.1</TITLE>
</HEAD>
 <BODY BGCOLOR="WHITE">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>EXHIBIT 5.1 </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">OPINION OF WILSON SONSINI GOODRICH&nbsp;&amp; ROSATI, </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">PROFESSIONAL CORPORATION </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">July&nbsp;2, 2015 </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Amphastar Pharmaceuticals,
Inc. </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">11570 6th Street </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Rancho Cucamonga, California 91730
</P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><B>Re:</B></TD>
<TD ALIGN="left" VALIGN="top"><B>Registration Statement on Form S-8</B> </TD></TR></TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Ladies and Gentlemen: </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">We have examined the Registration Statement on Form&nbsp;S-8 (the &#147;<B>Registration Statement</B>&#148;) to be filed by Amphastar
Pharmaceuticals, Inc., a Delaware corporation, with the Securities and Exchange Commission on or about the date hereof, in connection with the registration under the Securities Act of 1933, as amended, of an aggregate of 5,000,000 shares (the
&#147;<B>Shares</B>&#148;) of your common stock, par value $0.0001 per share (the &#147;<B>Common Stock</B>&#148;) reserved for issuance pursuant to the 2015 Equity Incentive Plan (the &#147;<B>Plan</B>&#148;). As your legal counsel, we have
reviewed the actions proposed to be taken by you in connection with the issuance and sale of the Shares to be issued under the Plan. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">It
is our opinion that the Shares, when issued and sold in the manner referred to in the Plan and pursuant to the agreements which accompany the Plan, will be legally and validly issued, fully paid and nonassessable. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">We consent to the use of this opinion as an exhibit to the Registration Statement, and further consent to the use of our name wherever
appearing in the Registration Statement and any amendments thereto. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


<TR>
<TD WIDTH="100%"></TD></TR>


<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Sincerely,</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">WILSON SONSINI GOODRICH&nbsp;&amp; ROSATI</TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Professional Corporation</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">/s/ Wilson Sonsini Goodrich&nbsp;&amp; Rosati, P.C.</TD></TR>
</TABLE></DIV>
</BODY></HTML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-23.1
<SEQUENCE>3
<FILENAME>d949153dex231.htm
<DESCRIPTION>EX-23.1
<TEXT>
<HTML><HEAD>
<TITLE>EX-23.1</TITLE>
</HEAD>
 <BODY BGCOLOR="WHITE">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>Exhibit 23.1 </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Consent of Independent Registered Public Accounting Firm </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">We consent to the incorporation by reference in the Registration Statement (Form S-8) pertaining to the 2015 Equity Incentive Plan of
Amphastar Pharmaceuticals, Inc. of our report dated March&nbsp;26, 2015, with respect to the consolidated financial statements of Amphastar Pharmaceuticals, Inc. included in its Annual Report (Form 10-K) for the year ended December&nbsp;31, 2014,
filed with the Securities and Exchange Commission. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">/s/ Ernst&nbsp;&amp; Young LLP </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Los Angeles, California </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">July&nbsp;2, 2015 </P>
</BODY></HTML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
