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 *

Zhang Jack Y.
2. Issuer Name and Ticker or Trading Symbol

Amphastar Pharmaceuticals, Inc. [ AMPH ]
5. Relationship of Reporting Person(s) to Issuer (Check all applicable)

__X__ Director                    __X__ 10% Owner
__X__ Officer (give title below)    _____ Other (specify below)
CEO & Chief Scientific Officer
(Last)          (First)          (Middle)

C/O AMPHASTAR PHARMACEUTICALS, INC., 11570 6TH STREET
3. Date of Earliest Transaction (MM/DD/YYYY)

3/16/2023
(Street)

RANCHO CUCAMONGA,, CA 91730
4. If Amendment, Date Original Filed (MM/DD/YYYY)

 
6. Individual or Joint/Group Filing (Check Applicable Line)

___ Form filed by One Reporting Person
_ X _ Form filed by More than One Reporting Person
(City)        (State)        (Zip)
Rule 10b5-1(c) Transaction Indication
Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

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 3/16/2023  G  57365 D$0.00 0 I See footnote (1)
Common Stock 3/16/2023  G  57365 D$0.00 0 I See footnote (2)
Common Stock 3/16/2023  F  25241 (3)D$37.60 2094486 (4)D  
Common Stock 3/16/2023  F  9998 (3)D$37.60 1462654 (5)I See footnote (6)
Common Stock 3/17/2023  F  15768 (3)D$36.29 2078718 D  
Common Stock 3/17/2023  F  7052 (3)D$36.29 1455602 I See footnote (6)
Common Stock         6827679 I See footnote (7)
Common Stock         5000 I See footnote (8)

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 Security3. Trans. Date3A. Deemed Execution Date, if any4. 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 Date7. 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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares

Explanation of Responses:
(1) The shares are held of record by The Jack Y. Zhang 2020 GRAT dated February 7, 2020, Jack Y. Zhang trustee (the "Zhang GRAT"). On February 7, 2020, Dr. Zhang contributed 353,797 shares of directly held Issuer common stock to the Zhang GRAT for the benefit of himself and his three adult children (the "Distributees"). Pursuant to the terms of the Zhang GRAT, upon termination of the Zhang GRAT, 57,365 of the shares were distributed to Distributees. The remaining 296,431 shares representing annuity payments under the Zhang GRAT were previously distributed to Dr. Zhang and continue to be reported in this Form 4 as directly owned by Dr. Zhang.
(2) The shares are held of record by The Mary Z. Luo 2020 GRAT dated February 7, 2020, Mary Z. Luo trustee (the "Luo GRAT"). On February 7, 2020, Dr. Luo contributed 353,797 shares of directly held Issuer common stock to the Luo GRAT for the benefit of herself and her three adult children (the "Distributees"). Pursuant to the terms of the Luo GRAT, upon termination of the Luo GRAT, 57,365 of the shares were distributed to Distributees. The remaining 296,431 shares representing annuity payments under the Luo GRAT were previously distributed to Dr. Luo and continue to be reported in this Form 4 as directly owned by Dr. Luo.
(3) The reported shares were withheld to satisfy the reporting person's tax liability in connection with the vesting of restricted stock units, or RSUs.
(4) Excludes 57,365 shares previously reported as held directly by Dr. Zhang as described in footnote (1) above.
(5) Excludes 57,365 shares previously reported as held directly by Dr. Luo as described in footnote (2) above.
(6) The securities are held of record by Dr. Luo. The reporting persons are husband and wife.
(7) The shares are held of record by Applied Physics & Chemistry Laboratories, Inc., of which the reporting persons and The Bill Luobei Zhang 2004 Irrevocable Trust are the sole owners.
(8) The shares are held of record in an account for the benefit of the reporting persons' son. The reporting persons disclaim beneficial ownership of these shares, and the inclusion of these shares in this report should not be deemed an admission of beneficial ownership of any such shares for purposes of Section 16, or for any other purpose.

Reporting Owners
Reporting Owner Name / Address
Relationships
Director10% OwnerOfficerOther
Zhang Jack Y.
C/O AMPHASTAR PHARMACEUTICALS, INC.
11570 6TH STREET
RANCHO CUCAMONGA,, CA 91730
XXCEO & Chief Scientific Officer
Luo Mary Z.
C/O AMPHASTAR PHARMACEUTICALS, INC.
11570 6TH STREET
RANCHO CUCAMONGA,, CA 91730
XXCOO,Chief Scientist & Chairman

Signatures
/s/ Eva Wen, by power of attorney for Jack Y. Zhang3/20/2023
**Signature of Reporting PersonDate

/s/ Eva Wen, by power of attorney for Mary Z. Luo3/20/2023
**Signature of Reporting PersonDate


Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
*If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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