2-PAM, Protopam Chloride
Classifications: antidote; Therapeutic: antidote
Pregnancy Category: C
1 g injection
Reactivates cholinesterase inhibited by phosphate esters by displacing the enzyme from its receptor sites; the free enzyme
then can resume its function of degrading accumulated acetylcholine, thereby restoring normal neuromuscular transmission.
More active against effects of anticholinesterases at skeletal neuromuscular junction than at autonomic effector sites or
in CNS respiratory center; therefore, atropine must be given concomitantly to block effects of acetylcholine and its accumulation
in these sites.
Antidote in treatment of poisoning by organophosphate insecticides and pesticides with anticholinesterase activity (e.g.,
parathion, TEPP, sarin) and to control overdosage by anticholinesterase drugs used in treatment of myasthenia gravis (cholinergic
To reverse toxicity of echothiophate ophthalmic solution.
Use in poisoning by carbamate; insecticide (Sevin), inorganic phosphates, or organophosphates having no anticholinesterase
activity; asthma, peptic ulcer, severe cardiac disease, patients receiving aminophylline, theophylline, morphine, succinylcholine,
reserpine, or phenothiazines; pregnancy (category C).
Myasthenia gravis; renal insufficiency; concomitant use of barbiturates in organophosphorus poisoning; lactation, children.
Route & Dosage
Adult: IV 12 g in 100 mL NS infused over 1530 min; or 12 g as 5% solution in sterile water over not less than
5 min, may repeat after 1 h if muscle weakness not relieved. IM/SC 12 g if IV route is not feasible.
Child: IV 2050 mg/kg. May repeat in 12 h if needed.
Anticholinesterase Overdose in Myasthenia Gravis
Adult: IV 12 g in 100 mL NS infused over 1530 min, followed by increments of 250 mg q5min prn
- Give only if unable to give IV; NOT preferred routes.
- Reconstitute as for direct IV injection (see below).
PREPARE: Direct: Reconstitute 1-g vial by adding 20 mL sterile water for injection to yield 50 mg/mL (a 5% solution). If pulmonary edema
is present, give without further dilution. IV Infusion: Preferred method is to further dilute in 100 mL NS.
ADMINISTER: Direct: In pulmonary edema, 1 g or fraction thereof over 5 min; do not exceed 200 mg/min. IV Infusion: Give over 1530 min (preferred).
- Stop infusion or reduce rate if hypertension occurs.
Adverse Effects (≥1%)CNS:
Dizziness, headache, drowsiness. GI:
Nausea. Special Senses:
Blurred vision, diplopia
, impaired accommodation. CV:
Tachycardia, hypertension (dose-related). Body as a Whole:
Hyperventilation, muscular weakness, laryngospasm,
May potentiate the effects of barbiturates
515 min IV
; 1020 min IM. Distribution:
Distributed throughout extracellular fluids; crosses bloodbrain barrier slowly if at all. Metabolism:
Probably in liver. Elimination:
Rapidly in urine. Half-Life:
Assessment & Drug Effects
- Monitor BP, vital signs, and I&O. Report oliguria or changes in I&O ratio.
- Monitor closely. It is difficult to differentiate toxic effects of organophosphates or atropine from toxic effects of pralidoxime.
- Be alert for and report immediately: Reduction in muscle strength, onset of muscle twitching, changes in respiratory pattern,
altered level of consciousness, increases or changes in heart rate and rhythm.
- Observe necessary safety precautions with unconscious patient because excitement and manic behavior reportedly may occur
following recovery of consciousness.
- Keep patient under close observation for 4872 h, particularly when poison was ingested, because of likelihood of continued
absorption of organophosphate from lower bowel.
- In patients with myasthenia gravis, overdosage with pralidoxime may convert cholinergic crisis into myasthenic crisis.