Material Agreement (Form 8-K)

Item 1.01. Entry into a Material Definitive Agreement.

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On October 21, 2025 (the "Effective Date") Amphastar Pharmaceuticals, Inc. ("Amphastar"), a wholly-owned subsidiary of Amphastar Pharmaceuticals, Inc. (the "Company"), and Nanjing Chengong Pharmaceutical Co., Limited ("Chengong"), a wholly-owned subsidiary of Nanjing Hanxin Pharmaceutical Technology Co., Ltd. ("Hanxin"), entered into a Distribution Agreement (the "Agreement") pursuant to which Amphastar and Chengong will collaborate to expand distribution of the Company's nasal powder product, BAQSIMI^®, in Mainland China, Taiwan, Hong Kong, and Macau in the Greater China region (the "Region"). Per the terms of the Agreement, Amphastar has appointed Chengong as the exclusive distributor to market and sell BAQSIMI^® in the Region. Chengong is responsible for obtaining any and all regulatory approvals in the Region, and performing the required post marketing clinical trials for BAQSIMI^®. During the term of the Agreement, Chengong is subject to minimum purchase amounts per contract year. Amphastar and Chengong will engage in profit sharing for any earnings above a certain floor price per unit, which will be determined using Chengong's per unit net revenue for BAQSIMI^®. Chengong has certain obligations with respect to the safety of data and quality control as set forth in a safety and data exchange agreement and quality agreement attached respectively as appendices to the Agreement and entered into in connection therewith. Each of Amphastar and Chengong have made customary representations, warranties and covenants in the Agreement. The term of the Agreement is for ten (10) years from the Effective Date and the parties may commence negotiations on an extension of the Agreement six (6) months prior to expiration. Both parties have termination rights without cause following the completion of the fourth (4^th) Contract Year. Payments under the Agreement will be made in U.S. dollars. The total revenue of the Agreement to the Company for the ten (10) year period of the Agreement is not determinable at this time as the per unit net revenues may vary over time.

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As previously disclosed in theDefinitive Proxy Statement for the Company's 2025 Annual Meeting of Stockholders, as filed with the SEC on Schedule 14A on April 14, 2025, Dr. Jack Zhang, the Company's Chief Executive Officer, President, and Director; and Dr. Mary Luo, the Company's Chairman, Chief Operating Officer, and Director; and certain members of their family beneficially own a majority of the equity interest in Hanxin, the parent of Chengong, and the Agreement between Amphastar and Chengong represents a related party transaction. Accordingly, the independent and disinterested members of the Audit Committee of the Board of Directors of the Company evaluated and approved entry into the Agreement following their review of applicable considerations.

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The foregoing is a brief description of the material terms of the Agreement, does not purport to be a complete description of the rights and obligations of the parties thereunder, and is qualified in its entirety by reference to the copy of the Agreement that will be filed as an exhibit to the Company's Quarterly Report on Form 10-Q to be filed with the Securities and Exchange Commission for the fiscal quarter ending September 30, 2025, and is incorporated herein by reference.

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