144 0001047579 XXXXXXXX LIVE 0001297184 Amphastar Pharmaceuticals, Inc. 001-36509 11570 6th Street Rancho Cucamonga CA 91730 909-980-9484 Richard Prins Director Common Stock UBS Financial Services Inc

1000 Harbor Blvd 3rd Floor Weehawken NJ 07086

7973 161931.63 44009000 08/11/2026 NASDAQ Common Stock 06/05/2024 RSU Vesting Issuer N 216 06/05/2024 N/A Common Stock 06/03/2025 RSU Vesting Issuer N 1567 06/03/2025 N/A Common Stock 06/07/2019 RSU Vesting Issuer N 2295 06/07/2019 N/A Common Stock 06/12/2020 RSU Vesting Issuer N 1395 06/12/2020 N/A Common Stock 06/07/2020 RSU Vesting Issuer N 295 06/07/2020 N/A Common Stock 06/09/2017 RSU Vesting Issuer N 271 06/09/2017 N/A Common Stock 06/08/2018 RSU Vesting Issuer N 1934 06/08/2018 N/A Y 08/11/2026 /s/Mijo Suric, for UBS Financial Services Inc, as attorney-in-fact for Richard Prins