X0306 4 2015-12-04 0 0001297184 Amphastar Pharmaceuticals, Inc. AMPH 0001611158 Applied Physics & Chemistry Laboratories, Inc. 13760 MAGNOLIA AVENUE CHINO CA 91710 0 0 1 0 Common Stock 2015-12-04 4 S 0 28712 14.952 D 7564299 D Common Stock 2015-12-07 4 S 0 15046 14.5879 D 7549253 D Common Stock 2015-12-08 4 S 0 24359 14.4964 D 7524894 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 4, 2015. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $14.835 to $15.36, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (2), (3) and (4) to this Form 4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $14.38 to $14.94, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $14.34 to $14.64, inclusive. Jack Y. Zhang (''Dr. Zhang'') is the Chief Executive Officer and a director of the Issuer and Mary Z. Luo (''Dr. Luo'') is the Chief Operating Officer and Chairman of the Board of Directors of the Issuer. Drs. Zhang and Luo are the sole owners of the Reporting Person and have shared voting and investment power of the Reporting Person. /s/ Ken Stupak, Corporate Counsel 2015-12-08