X0306 4 2016-03-17 0 0001297184 Amphastar Pharmaceuticals, Inc. AMPH 0001611157 Zhang Jack Y. C/O AMPHASTAR PHARMACEUTICALS, INC. 11570 6TH STREET RANCHO CUCAMONGA CA 91730 1 1 1 0 CEO & Chief Science Officer 0001611156 Luo Mary Z. C/O AMPHASTAR PHARMACEUTICALS, INC. 11570 6TH STREET RANCHO CUCAMONGA CA 91730 1 1 0 0 COO, Chief Scientist, Chairman Common Stock 2016-03-17 4 A 0 184466 0.00 A 1129902 D Common Stock 2016-03-17 4 A 0 79435 0.00 A 767666 I See footnote Common Stock 7461594 I See footnote Common Stock 5000 I See footnote Common Stock 200000 I See footnote Employee Stock Option (right to buy) 12.46 2016-03-17 4 A 0 722046 0.00 A 2024-03-17 Common Stock 722046 722046 D Employee Stock Option (right to buy) 12.46 2016-03-17 4 A 0 310930 0.00 A 2024-03-17 Common Stock 310930 310930 I See footnote The reported shares are represented by deferred stock units, or DSUs, which vest in three equal annual installments beginning on March 17, 2017. The securities are held of record by Mary Z. Luo. The reporting persons are husband and wife. The securities are held of record by APCL, of which the reporting persons are the sole owners. 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. The shares are held of record by a trust 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. Shares subject to the option vest in three equal annual installments beginning on March 17, 2017. /s/ Ken Stupak, by power of attorney for Jack Y. Zhang 2016-03-21 /s/ Ken Stupak, by power of attorney for Mary Z. Luo 2016-03-21