[13] The drug is used to treat Lambert–Eaton myasthenic syndrome (LEMS), which is a rare neuromuscular disorder characterized by muscle weakness of the limbs, affecting about 3.4 per million people.

[20] As of 2022, the company offered Catalyst Pathways, a program that provides financial aid, insurance navigation, bridge medicine, and Patient Access Liaisons.

[23] In March 2024, Catalyst commercially launched AGAMREE (vamorolone) oral suspension for the treatment of Duchenne muscular dystrophy in patients aged two years and older.

[24] [25] In May 2024, the FDA approved a supplemental New Drug Application increasing the indicated maximum daily dose of Firdapse (amifampridine) for adults and pediatric patients weighing more than 45 kg from 80 mg to 100 mg.[26] Tentative evidence supports 3,4-diaminopyridine treatment at least for a few weeks, with the goal to improve neuromuscular transmission.

[33] In December 2015 a group of neuromuscular doctors published an editorial in the journal, Muscle & Nerve, with concerns about the potential for the price to be increased should Catalyst obtain FDA approval, and stating that 3,4-DAPP represented no real innovation and didn't deserve exclusivity under the Orphan Drug Act.

[33][34] Catalyst responded to this editorial with a response in 2016 that explained they were conducting a full range of clinical and non-clinical studies necessary to obtain approval in order to specifically address the unmet need among the estimated 1500-3000 LEMs patients since about 200 were receiving the product through compassionate use – and that this is exactly what the Orphan Drug Act was intended to do.

With this decision, the Eleventh Circuit rejected the FDA's interpretation of orphan exclusivity and concluded that the agency had improperly approved a competitor product from Jacobus Pharmaceutical Co.[39][40] On February 4, 2019, Bernie Sanders, United States Senator from Vermont, publicly sent a letter to Catalyst asking why they raised the price of their drug Firdapse to an annual cost of $375,000, considering Firdapse was previously free of charge through an FDA compassionate use program.

Catalyst responded by saying, “The approval of Firdapse by the FDA means that all LEMS patients in the United States now have access to this much-needed medication”.