SCHEDULE 13G

CUSIP No.

03209R103

Names of Reporting Persons

Jack Y. Zhang

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

CHINA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 3,899,921.00
6	Shared Voting Power 8,624,232.00
7	Sole Dispositive Power 3,899,921.00
8	Shared Dispositive Power 8,624,232.00

Aggregate Amount Beneficially Owned by Each Reporting Person

12,524,153.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

24.8 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: The shares set forth in Row 9 include (i) 2,312,948 shares of common stock held of record by Jack Y. Zhang; (ii) 1,586,973 shares of common stock that are issuable upon exercise of outstanding options within 60 days of December 31, 2024 by Dr. Zhang; (iii) 1,021,492 shares of common stock held of record by Mary Z. Luo, Dr. Zhang's spouse; (iv) 775,061 shares of common stock that are issuable upon exercise of outstanding options within 60 days of December 31, 2024 by Dr. Luo; and (v) 6,827,679 shares of common stock held of record by Applied Physics & Chemistry Laboratories, Inc., or APCL, of which Dr. Zhang, Dr. Luo and The Bill Luobei Zhang 2004 Irrevocable Trust are the sole owners. The percentage set forth in Row 11 is based on 48,081,433 shares of the Issuer's common stock outstanding as of November 1, 2024, as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2024, filed with the Securities and Exchange Commission on November 7, 2024.

SCHEDULE 13G

CUSIP No.

03209R103

Names of Reporting Persons

Mary Z. Luo

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 1,796,553.00
6	Shared Voting Power 10,727,600.00
7	Sole Dispositive Power 1,796,553.00
8	Shared Dispositive Power 10,727,600.00

Aggregate Amount Beneficially Owned by Each Reporting Person

12,524,153.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

24.8 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: The shares set forth in Row 9 include (i) 1,021,492 shares of common stock held of record by Mary Z. Luo; (ii) 775,061 shares of common stock that are issuable upon exercise of outstanding options within 60 days of December 31, 2024 by Dr. Luo; (iii) 2,312,948 shares of common stock held of record by Jack Y. Zhang, Dr. Luo's spouse; (iv) 1,586,973 shares of common stock that are issuable upon exercise of outstanding options within 60 days of December 31, 2024 by Dr. Zhang; and (v) 6,827,679 shares of common stock held of record by Applied Physics & Chemistry Laboratories, Inc., or APCL, of which Dr. Luo, Dr. Zhang and The Bill Luobei Zhang 2004 Irrevocable Trust are the sole owners. The percentage set forth in Row 11 is based on 48,081,433 shares of the Issuer's common stock outstanding as of November 1, 2024, as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2024, filed with the Securities and Exchange Commission on November 7, 2024.

SCHEDULE 13G

CUSIP No.

03209R103

Names of Reporting Persons

Applied Physics & Chemistry Laboratories, Inc.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

CALIFORNIA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 6,827,679.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 6,827,679.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

6,827,679.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

14.2 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person: Jack Y. Zhang, Mary Z. Luo and The Bill Luobei Zhang 2004 Irrevocable Trust, the sole owners of Applied Physics & Chemistry Laboratories, Inc., or APCL, have shared voting and dispositive power over the shares set forth in Row 9. The percentage set forth in Row 11 is based on 48,081,433 shares of the Issuer's common stock outstanding as of November 1, 2024, as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2024, filed with the Securities and Exchange Commission on November 7, 2024.

SCHEDULE 13G

Item 1.

(a)

Name of issuer:

Amphastar Pharmaceuticals, Inc.

(b)

Address of issuer's principal executive offices:

11570 6th Street Rancho Cucamonga, CA, 91730

Item 2.

(a)

Name of person filing:

Jack Y. Zhang Mary Z. Luo Applied Physics & Chemistry Laboratories, Inc.

(b)

Address or principal business office or, if none, residence:

The address for the principal business office of Dr. Zhang and Dr. Luo is: c/o Amphastar Pharmaceuticals, Inc. 11570 6th Street Rancho Cucamonga, California 91730 The address for the principal business office of APCL is: 13760 Magnolia Avenue Chino, California 91710

(c)

Citizenship:

Reference is hereby made to the response to item 4 on each of pages 2-4 of this Schedule 13G (this "Schedule"), which responses are incorporated herein by reference.

(d)

Title of class of securities:

Common Stock

(e)

CUSIP No.:

03209R103

Item 3.

If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)

An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);

(f)

An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);

(g)

A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h)

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:

(k)

Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).

Item 4.

Ownership

(a)

Amount beneficially owned:

Reference is hereby made to the responses to items 5-9 of each of pages 2-4 of this Schedule, which responses are incorporated herein by reference.

(b)

Percent of class:

Reference is hereby made to the response to item 11 on each of pages 2-4 of this Schedule, which responses are incorporated herein by reference.

(c)

Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote:

Reference is hereby made to the response to item 5 on each of pages 2-4 of this Schedule, which responses are incorporated herein by reference.

(ii) Shared power to vote or to direct the vote:

Reference is hereby made to the response to item 6 on each of pages 2-4 of this Schedule, which responses are incorporated herein by reference.

(iii) Sole power to dispose or to direct the disposition of:

Reference is hereby made to the response to item 7 on each of pages 2-4 of this Schedule, which responses are incorporated herein by reference.

(iv) Shared power to dispose or to direct the disposition of:

Reference is hereby made to the response to item 8 on each of pages 2-4 of this Schedule, which responses are incorporated herein by reference.

Item 5.

Ownership of 5 Percent or Less of a Class.

Item 6.

Ownership of more than 5 Percent on Behalf of Another Person.

Not Applicable

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Not Applicable

Item 8.

Identification and Classification of Members of the Group.

Not Applicable

Item 9.

Notice of Dissolution of Group.

Not Applicable

Item 10.

Certifications:

Not Applicable

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Jack Y. Zhang

Signature:	/s/ Jack Y. Zhang
Name/Title:	Jack Y. Zhang
Date:	02/07/2025

Mary Z. Luo

Signature:	/s/ Mary Z. Luo
Name/Title:	Mary Z. Luo
Date:	02/07/2025

Applied Physics & Chemistry Laboratories, Inc.

Signature:	/s/ Jack Y. Zhang
Name/Title:	Jack Y. Zhang, President
Date:	02/07/2025

Exhibit Information

Exhibit 99.1 Joint Filing Agreement, dated February 5, 2015, by and among Jack Yongfeng Zhang, Mary Ziping Luo and Applied Physics & Chemistry Laboratories, Inc. https://www.sec.gov/Archives/edgar/data/1297184/000110465915009569/a15-4133_1ex99d1.htm filed with the SEC as Exhibit 99.1 to the Schedule 13G on February 12, 2015.