Amphastar Pharmaceuticals, Inc. engages in developing, manufacturing, marketing, and selling technically challenging generic and proprietary injectable, inhalation, and intranasal products, and insulin active pharmaceutical ingredient. It operates through Finished Pharmaceutical Products and Active Pharmaceutical Ingredients Products segments. The Finished Pharmaceutical Products segment manufactures, markets, and distributes Primatene Mist, enoxaparin, naloxone, phytonadione, lidocaine, and other critical and non-critical care drugs. The Active Pharmaceutical Ingredients Products segment offers RHI API and porcine insulin API for external customers and internal product development. The company was founded by Zi-Ping Luo and Yong Feng Zhang on February 29, 1996 and is headquartered in Rancho Cucamonga, CA.