FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).         
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
                                                                                  
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940
                       
1. Name and Address of Reporting Person * Zhou Rong 2. Issuer Name and Ticker or Trading Symbol Amphastar Pharmaceuticals, Inc. [ AMPH ] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable)_____ Director                    _____ 10% Owner
__X__ Officer (give title below)    _____ Other (specify below)
EVP, Production Center
(Last)         (First)         (Middle)
C/O AMPHASTAR PHARMACEUTICALS, INC., 11570 6TH STREET		 3. Date of Earliest Transaction (MM/DD/YYYY)
6/3/2020
(Street)
RANCHO CUCAMONGA, CA 91730
(City)       (State)       (Zip)
 4. If Amendment, Date Original Filed (MM/DD/YYYY)
 
 6. Individual or Joint/Group Filing (Check Applicable Line) _X _ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Trans. Date 2A. Deemed Execution Date, if any 3. Trans. Code
(Instr. 8)		 4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)		 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V Amount (A) or (D) Price
Common Stock  6/3/2020    M    11082  A $11.41  93287 (1) D   
Common Stock  6/3/2020    S    13163  D $18.8162 (2) 80124  D   
Common Stock  6/4/2020    M    8918  A $11.41  89042  D   
Common Stock  6/4/2020    S    9806  D $19.19  79236  D   
Common Stock                 99668  I  See footnote (3)
Common Stock                 5000  I  See footnote (4)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security
(Instr. 3)		 2. Conversion or Exercise Price of Derivative Security 3. Trans. Date 3A. Deemed Execution Date, if any 4. Trans. Code
(Instr. 8)		 5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 6. Date Exercisable and Expiration Date 7. Title and Amount of Securities Underlying Derivative Security
(Instr. 3 and 4)		 8. Price of Derivative Security
(Instr. 5)		 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Employee Stock Option (right to buy)  $11.41  6/3/2020    M        11082    (5) 3/8/2021  Common Stock  11082  $0  8918  D   
Employee Stock Option (right to buy)  $11.41  6/4/2020    M        8918    (5) 3/8/2021  Common Stock  8918  $0  0  D   

Explanation of Responses:
(1)  Includes 1,314 shares acquired under the Issuer's 2014 Employee Stock Purchase Plan on May 31, 2020.
(2)  The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $18.7903 to $18.915, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.
(3)  The shares are held of record by the Zhou Family Trust for which the reporting person serves as a trustee.
(4)  The shares are held of record by the reporting person's spouse.
(5)  Shares subject to the option are fully vested and immediately exercisable.

Reporting Owners
Reporting Owner Name / Address
Relationships
Director 10% Owner Officer Other
Zhou Rong
C/O AMPHASTAR PHARMACEUTICALS, INC.
11570 6TH STREET
RANCHO CUCAMONGA, CA 91730

EVP, Production Center

Signatures
/s/ Eva Wen, by power of attorney 6/5/2020
**Signature of Reporting Person Date