The company said that this marks the first FDA approved starting material from its Chinese subsidiary ANP, and signifies that this facility has been qualified by the FDA.
According to IMS Health sales data, amphadase will compete in the hyaluronidase market, which had sales of $23m for the 12 months ended 31 March 2015.
Amphadase is designed to improve the resorption of radiopaque agents and the company intends to re-launch the product in the fourth quarter of this year.
Amphastar CEO Dr Jack Zhang said: "We are very happy to have received approval of Amphadase.
"In addition to its monetary value, this approval further strengthens our vertical integration strategy, given that ANP will provide the key APIs and starting materials for our pipeline."
Currently, the company has three abbreviated new drug applications (ANDAs) filed with the FDA targeting products with a market size of over $0.5bn, and another ten generic products in development targeting products with a market size of over $15bn.
The company is currently developing six other proprietary drugs such as injectables, inhalation products, nasal sprays and other dosage forms.