X0206 3 2015-06-09 0 0001297184 Amphastar Pharmaceuticals, Inc. AMPH 0001645326 Zhou Rong C/O AMPHASTAR PHARMACEUTICALS, INC. 11570 6TH STREET RANCHO CUCAMONGA CA 91730 0 1 0 0 EVP, Production Common Stock 25688 D Common Stock 99668 I See footnote Common Stock 5000 I See footnote Employee stock option (right to buy) 30.57 2016-12-21 Common Stock 12000 D Employee stock option (right to buy) 31.65 2017-12-30 Common Stock 24000 D Employee stock option (right to buy) 35.32 2018-08-28 Common Stock 16000 D Employee stock option (right to buy) 20.26 2019-08-05 Common Stock 16000 D Employee stock option (right to buy) 11.41 2021-03-08 Common Stock 20000 D Employee stock option (right to buy) 14.23 2021-12-22 Common Stock 20000 D Employee stock option (right to buy) 10.48 2022-11-07 Common Stock 25000 D Employee stock option (right to buy) 10.93 2023-07-30 Common Stock 28000 D Employee stock option (right to buy) 14.40 2024-04-14 Common Stock 32891 D Employee stock option (right to buy) 14.95 2025-03-26 Common Stock 18524 D Includes 6,187 shares represented by deferred stock units, or DSUs, which vest in four equal annual installments beginning on March 26, 2016. The shares are held of record by the Zhou Family Trust for which the reporting person serves as a trustee. The shares are held of record by the reporting person's spouse. Shares subject to the option are fully vested and immediately exercisable. Shares subject to the option vest in five equal annual installments beginning on March 8, 2012. Shares subject to the option vest in four equal annual installments beginning on December 22, 2012. Shares subject to the option vest in four equal annual installments beginning on November 7, 2013. Shares subject to the option vest in four equal annual installments beginning on July 30, 2014. Shares subject to the option vest in four equal annual installments beginning on April 14, 2015. Shares subject to the option vest in four equal annual installments beginning on March 26, 2016. Exhibit 24 - Power of Attorney /s/ Ken Stupak, by power of attorney 2015-06-17