 RANCHO CUCAMONGA, Calif., April 29, 2021 GLOBE NEWSWIRE -- Amphastar Pharmaceuticals, Inc. NASDAQ: AMPH announced that the Company will release results for its first quarter of 2021 ended March 31, 2021, after the market closes on Thursday, May 6th, 2021, and will hold a conference call to discuss its financial results at 2:00 p.m. Pacific Time. 