pyridostigmina

Pyridostigmina, also known as pyridostigmine bromide, is a reversible acetylcholinesterase inhibitor of the carbamate class. It increases the concentration of acetylcholine at the neuromuscular junction, improving transmission between nerves and muscles. It is primarily used for symptomatic treatment of myasthenia gravis, where it helps improve muscle strength and reduces fatigability. The medication is usually taken orally as tablets or solution, with dosing tailored to the individual and often started around 30 mg every 4 to 6 hours. It may be given by other routes in certain settings, but oral administration is most common. The drug is a quaternary ammonium compound and therefore has limited penetration into the central nervous system.

Pyridostigmina has also been used as a prophylactic pretreatment in some military contexts to provide limited protection against certain nerve agents, such as soman, under regulatory guidance. This use is not a substitute for standard antidotes and is subject to specific protocols.

Mechanism and pharmacokinetics: By carbamylating acetylcholinesterase, pyridostigmine reduces the breakdown of acetylcholine, increasing its availability at the neuromuscular junction. Onset after dosing is typically 15 to 60 minutes, with peak effects in about 1–2 hours and a duration of 3–6 hours. CNS effects are minimal due to poor CNS penetration. It is mainly eliminated by the kidneys, and renal impairment may necessitate dose adjustments.

Adverse effects and interactions: Cholinergic side effects—nausea, abdominal cramps, diarrhea, increased salivation, sweating, lacrimation, miosis, bradycardia, and fasciculations—can occur, especially at higher doses. Overdose may cause a cholinergic crisis; treatment includes atropine. Coadministration with other cholinesterase inhibitors or anticholinergic drugs can alter efficacy and safety.