ALSUntangled #81: Pyridostigmine (mestinon®).

Pyridostigmine (Mestinon®, Bausch Health, Canada Inc.) increases acetylcholine availability at the neuromuscular junction, enhancing transmission. Preclinical studies suggest that neuromuscular junction dysfunction develops early in ALS, and pyridostigmine may temporarily improve neuromuscular transmission. However, altered neuromuscular junction transmission has uncertain benefits in ALS progression. Pyridostigmine does not have other plausible mechanisms that truly modify ALS pathophysiology. People with ALS (PALS) who have positive acetylcholine receptor autoantibodies and no myasthenia symptoms are unlikely to respond to pyridostigmine treatment. Clinical trials on pyridostigmine in PALS are lacking, but two clinical trials of other similar anticholinesterase agents did not effectively slow ALS progression. Muscarinic cholinergic side effects, including gastrointestinal symptoms, are common. Given the lack of mechanistic plausibility and efficacy, we do not support the use of pyridostigmine for slowing ALS progression.