Amphastar Pharmaceuticals, Inc.

Except as noted below, there were no material changes from the risk factors previously disclosed in our Annual Report on Form 10-K for the year ended December 31, 2025, filed with the SEC on February 26, 2026.

We must manufacture our drug products at our facilities in conformity with cGMP regulations; failure to maintain compliance with cGMP regulations may prevent or delay the manufacture or marketing of our products or product candidates and may prevent us from gaining approval of our products.

All of our products and product candidates for use in clinical studies must be manufactured, packaged, labeled and stored in accordance with cGMP. For our approved products, modifications, enhancements, or changes in manufacturing processes and sites may require supplemental FDA approval, which may be subject to a lengthy application process or which we may be unable to obtain.

All facilities of Amphastar, our subsidiaries and our CMOs and suppliers are periodically subject to inspection by the FDA and other governmental entities, and operations at these facilities could be interrupted or halted if the FDA or another governmental entity deems such inspections as unsatisfactory. For example, our facilities in Rancho Cucamonga, CA, South El Monte, CA, Canton, MA, Éragny Sur Epte, France, and Nanjing, China are subject to FDA cGMP inspections as well as pre-approval, routine and other inspections by the FDA, state, and other regulatory authorities and may be again in the future per applicable law. Our facility in South El Monte, CA was inspected by the FDA in December 2025, and we responded to the Form 483 observations in January 2026. Subsequently, in April 2026, the FDA notified us that the facility would be classified as “Official Action Indicated.” We have undertaken corrective actions to address the observations noted in the Form FDA 483 and do not anticipate any interruption that could have a material adverse effect on Amphastar and its operations.

Compliance with cGMP standards requires substantial expenditures of time, money and effort in such areas as production and quality control to ensure full technical compliance. Failure to comply with cGMP or with other state, federal, or foreign requirements may result in unanticipated compliance expenditures, total or partial suspension of production or distribution, suspension of review of applications submitted for approval of our product candidates, termination of ongoing research, disqualification of data derived from studies on our products and/or enforcement actions such as recall or seizure of products, injunctions, civil penalties and criminal prosecutions of the company and company officials. There can be no assurance that we will be able to remedy any deficiencies cited by FDA or other regulatory agencies in their inspections.

Jack Y. Zhang and Mary Z. Luo have each pledged shares of our common stock to secure funds borrowed under existing credit lines from three financial institutions. Each of the lenders has varying rights as a lender, including one which has the right to conduct a forced sale at its sole discretion. An action by one of the lenders could include a sale of certain shares of our common stock pledged as collateral, the sale of which could cause the price of our common stock to decline. An action to cure and cover indebtedness by any one of the lenders could also have other negative impacts on our business.

Jack Y. Zhang and Mary Z. Luo have each pledged shares of our common stock to secure funds borrowed under existing credit lines by UBS Group and its affiliates, or UBS, East West Bank, or East West, and Cathay Bank. As of March 31, 2026, UBS had extended combined credit lines of $15.0 million to Applied Physics & Chemistry Laboratories, Inc., or APCL, which is controlled by Dr. Zhang and Dr. Luo, East West had agreed to a loan of up to $12.0 million to Drs. Zhang and Luo, and Cathay Bank had agreed to a loan of up to $30.0 million to APCL and Dr. Luo. The UBS credit lines are secured by a pledge of 1,500,000 shares of our common stock currently held by APCL, the East West loan is secured by a pledge of 1,200,000 shares of our common stock held by APCL and Dr. Zhang, and the Cathay Bank loan is secured by a pledge of 3,000,000 shares of our common stock held by APCL and Dr. Luo. Interest on each of these

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loans accrues at market rates. UBS has an unlimited and unilateral right to call each of the credit lines for any reason whatsoever, and each of East West and Cathay Bank has acceleration rights to protect itself in the event of a default.

We have a pledging policy to restrict the pledging of shares by our executive officers and directors, which was created in 2021 and most recently amended in 2026. The policy prohibits our executive officers and directors from entering into any transaction whereby the executive officer or director, directly or indirectly, pledges, hypothecates, or otherwise encumbers more than sixty (60) percent of shares of common stock held by the individual or more than fifteen (15) percent of our total outstanding shares of common stock as of the date of the transaction, whichever is lower, as collateral for indebtedness. This restriction extends to any hedging or similar transaction designed to decrease the risks associated with holding our securities.

While we are not a party to these loans, which are full recourse against APCL and each of Drs. Zhang and Luo, respectively, and are secured by pledges of a portion of the shares of our common stock currently held by APCL and each of Drs. Zhang and Luo, if the price of our common stock declines, Drs. Zhang and Luo may be forced by these financial institutions to provide additional collateral for the loans or to sell shares of our common stock held by them in order to remain within the margin limitations imposed under the terms of their loans. Furthermore, the pledged shares of our common stock may be acquired and sold by the lenders. These factors may limit Drs. Zhang and Luo’s ability to either pledge additional shares of our common stock or sell shares of our common stock held by them as a means to avoid or satisfy a margin call with respect to their pledged shares of our common stock in the event of a decline in our stock price that is large enough to trigger a margin call. Any significant sales of shares of our common stock by one or more of these three lenders could cause the price of our common stock to decline further.