pralidoxima

Pralidoxime, also known as pralidoxime chloride or 2-PAM, is an antidote used to treat organophosphate poisoning by reactivating acetylcholinesterase that has been inhibited by organophosphates. It acts as a nucleophilic oxime, cleaving the bond between the organophosphate and the enzyme to restore enzyme activity and reduce both nicotinic and some muscarinic symptoms. Its effectiveness depends on timing and the chemical form of the agent, because aging of the enzyme–organophosphate complex can render reactivation unlikely.

Indications for pralidoxime include life-threatening organophosphate poisoning from pesticides or nerve agents, typically as part of a treatment regimen with atropine. It is not generally effective for poisoning by carbamates and some other cholinesterase inhibitors, and its use in such cases is limited or not recommended.

Administration is parenteral, given by intravenous or intramuscular injection. A common adult regimen starts with a loading dose of about 1–2 g IV, followed by a continuous infusion of roughly 0.5 g per hour for several hours; dosing can be adjusted based on clinical response and the agent involved. Pediatric dosing is weight-based. The timing of administration is important; earlier treatment increases the chances of successful enzyme reactivation.

Contraindications are mainly hypersensitivity to pralidoxime. Caution is advised in renal impairment, and concomitant use with atropine is common to manage muscarinic symptoms. Possible adverse effects include dizziness, nausea, tachycardia, hypertension, blurred vision, and injection-site reactions.

Pharmacokinetically, pralidoxime is hydrophilic and has limited blood-brain barrier penetration, with renal excretion as a primary route of elimination.