X0306 4 2014-07-07 0 0001297184 Amphastar Pharmaceuticals, Inc. AMPH 0001611147 Purchase Marilyn J. C/O AMPHASTAR PHARMACEUTICALS, INC. 11570 6TH STREET RANCHO CUCAMONGA CA 91730 0 1 0 0 Corp. Exec. VP of Operations Common Stock 2014-07-07 4 F 0 1239 8.75 D 31375 D Common Stock 2014-10-03 4 F 0 519 11.41 D 30856 D Common Stock 2015-03-26 4 A 0 14046 0 A 44902 D Common Stock 16044 I See footnote Employee Stock Option (right to buy) 14.95 2015-03-26 4 A 0 42054 0 A 2025-03-26 Common Stock 42054 42054 D The reported securities were withheld to satisfy the Reporting Person's tax liability in connection with the vesting of deferred stock units (DSUs). Excludes 16,044 shares previously reported as held directly. The reported securities are represented by DSUs which vest in four equal annual installments beginning on March 26, 2016. All of the reported shares were previously reported as held directly. The shares are held directly by the Purchase Family Trust for which the Reporting Person serves as co-trustee. Shares subject to the option vest in four equal annual installments beginning on March 26, 2016. /s/ Ken Stupak, by power of attorney 2015-03-27