Amifampridine phosphate

As Part of the Settlement, Hetero Labs Ltd. Receives a License to Market Generic FIRDAPSE Beginning in January 2035 Catalyst has No Other FIRDAPSE Patent Litigation Pending CORAL GABLES, Fla., May 07, 2026 (GLOBE NEWSWIRE) -- Catalyst Pharmaceuticals, Inc. (“Catalyst” or “Company”) (Nasdaq: CPRX), a commercial-stage biopharmaceutical company focused on in-licensing, developing, and commercializing novel medicines for patients living with rare and difficult-to-treat diseases, today announced that the Company and its licensor SERB S.A. (“SERB”) have entered into a Settlement Agreement (“Agreement”) with Hetero Labs Ltd., Hetero USA, Grace Consulting Services, Inc., and Annora Pharma Private Limited (collectively, Hetero). This Agreement resolves the patent litigation brought by Catalyst and SERB in response to Hetero’s Abbreviated New Drug Application (“ANDA”) seeking approval to market a generic version of FIRDAPSE® (amifampridine) 10 mg tablets prior to expiration of the applicable patents. Pursuant to the terms of the Agreement, Hetero will not market its generic version of FIRDAPSE in the United States any earlier than a specified date in January 2035, if approved by the U.S. Food and Drug Administration, unless certain limited circumstances customarily included in these types of agreements occur. In accordance with the Agreement, the parties will terminate all ongoing patent litigation between Catalyst/SERB and Hetero regarding FIRDAPSE patents pending in the U.S. District Court for the District of New Jersey prior to the scheduled trial commencement on May 18, 2026. Catalyst previously settled similar litigation regarding ANDA applications for FIRDAPSE with Lupin Pharmaceuticals, Teva Pharmaceuticals, and Inventia Healthcare Limited. This settlement resolves all pending patent litigation relating to FIRDAPSE. As required by law, the companies will submit the confidential settlement agreement to the U.S. Federal Trade Commission and the U.S. Department of Justice for review. About Catalyst Pharmaceuticals, Inc.Catalyst Pharmaceuticals, Inc. (Nasdaq: CPRX), is a biopharmaceutical company committed to improving the lives of patients with rare diseases. With a proven track record of bringing life-changing treatments to the market, we focus on in-licensing, commercializing, and developing innovative therapies. Guided by our deep commitment to patient care, we prioritize accessibility, ensuring patients receive the care they need through a comprehensive suite of support services designed to provide seamless access and ongoing assistance. Catalyst maintains a well-established U.S. presence, which remains the cornerstone of our commercial strategy, while continuously evaluating strategic opportunities to expand our global footprint. Catalyst, headquartered in Coral Gables, Fla., was recognized on the Forbes 2025 list as one of America's Most Successful Mid-Cap Companies and on the 2024 Deloitte Technology Fast 500™ list as one of North America’s Fastest-Growing Companies. For more information, please visit Catalyst's website at www.catalystpharma.com. Forward-Looking StatementsThis press release contains forward-looking statements, as that term is defined in the Private Securities Litigation Reform Act of 1995. Forward-looking statements involve known and unknown risks and uncertainties, which may cause Catalyst's actual results in future periods to differ materially from forecasted results. A number of factors, including those factors described in Catalyst's Annual Report on Form 10-K for the fiscal year 2025 and its other filings with the U.S. Securities and Exchange Commission ("SEC"), could adversely affect Catalyst. Copies of Catalyst's filings with the SEC are available from the SEC, may be found on Catalyst's website, or may be obtained upon request from Catalyst. Catalyst does not undertake any obligation to update the information contained herein, which speaks only as of this date. Source: Catalyst Pharmaceuticals, Inc. Investor Contact Melissa Kendis, Catalyst Pharmaceuticals, Inc. (305) 420-3200 IR@catalystpharma.com Media Contact Jed Repko / Mahmoud Siddig Joele Frank, Wilkinson Brimmer Katcher (212) 355-4449

Angelini Pharma is spending $4.1 billion to buy Catalyst Pharmaceuticals and its trio of FDA-approved treatments for rare neurological diseases. The buyout will add three medicines to Angelini’s portfolio: Firdapse for Lambert-Eaton myasthenic syndrome, Agamree for Duchenne muscular dystrophy and Fycompa for partial-onset seizures and primary generalized tonic-clonic seizures. The Italian pharma said the move will allow it to enter the US market, and also aligns with its historical and current focus on brain diseases. Angelini will buy all of Catalyst’s shares for $31.50 apiece. That figure represents a 21% markup on Catalyst’s share price $CPRX on April 22, which was the last day “before market signs that the transaction had become public information,” according to a release. Catalyst will operate as a wholly-owned subsidiary of Angelini after the deal closes, which is expected in the third quarter. Firdapse and Agamree are expected to pull about $443 million and $146 million, respectively, in global sales this year, according to Visible Alpha consensus estimates. Catalyst’s total US sales in 2025 grew almost 20% from the year prior to reach $589 million . The three drugs are also approved in Europe but marketed by other companies. Also on Thursday, Catalyst said in a separate release that it has now resolved all Firdapse patent disputes. The drugmaker said that it has settled with generic drugmaker Hetero Labs, which can start marketing generic Firdapse from January 2035 under the terms of the agreement. Catalyst previously settled other Firdapse disputes with Lupin Pharmaceuticals, Teva Pharmaceuticals and Inventia Healthcare. Catalyst’s efforts to expand Firdapse’s label have been unsuccessful, with the drug flunking a Phase 3 myasthenia gravis trial six years ago. The Florida-headquartered company has no new drug candidates in its pipeline. In February, it had 182 employees in total, 128 of which are in the commercial arm and eight in R&D.