Pralidoxim

Pralidoxim, also known as pralidoxime chloride or 2-PAM, is a medication used in the treatment of organophosphate poisoning and certain nerve agent exposures. It is a cholinesterase reactivator intended to restore the activity of acetylcholinesterase inhibited by organophosphates.

Mechanism of action is as an oxime that binds to the phosphorylated acetylcholinesterase enzyme and cleaves the bond between the enzyme and the organophosphate inhibitor, thereby reactivating the enzyme. Pralidoxim is a quaternary compound and has limited ability to cross the blood–brain barrier, so it primarily addresses peripheral effects. Its effectiveness depends on the age of the enzyme–OP complex; once aging occurs, reactivation is not possible.

Indications include suspected or confirmed organophosphate poisoning, used in combination with atropine to treat muscarinic symptoms. It may be ineffective for certain carbamate poisonings and is not routinely used for non-organophosphate toxicities. Pralidoxim is administered by injection, typically intravenously or intramuscularly, with dosing tailored to age and weight and under close clinical supervision.

Common dosing regimens for adults involve an initial intravenous bolus of 1 to 2 grams over 15 to 30 minutes, potentially followed by additional doses every 4 to 6 hours or by a continuous infusion, depending on severity and response. Pediatric dosing is weight-based. Dosing must be adjusted for renal impairment and monitored for adverse effects.

Adverse effects are usually mild but can include nausea, dizziness, tachycardia, hypertension, or hypersensitivity reactions. Contraindications include known hypersensitivity to pralidoxime. Caution is advised in patients with renal impairment, and concurrent use with other cholinergic or anticholinergic medications should be managed carefully.

Availability includes brand names such as Protopam; it is supplied as a chloride salt formulation.