Firdapse(Amifampridine) Side Effects

The most frequent adverse reactions (>10%) are paresthesia, upper respiratory infections, abdominal pain, nausea, diarrhea, headache, elevated liver enzymes, back pain, hypertension, and muscle spasms. Serious risks include seizures (2% incidence) and hypersensitivity reactions (e.g., anaphylaxis). Overdose (exceeding 80 mg/day) may cause convulsions, cardiac arrhythmias, or cardiac arrest. Elevated liver enzymes necessitate monitoring but were transient in trials. Drug interactions exacerbate cholinergic effects or seizure risks. Renal/hepatic impairment or slow acetylator status increases drug exposure, heightening adverse event likelihood. Management involves dose reduction, discontinuation, or symptomatic treatment. Long-term safety data beyond 18 months are limited.