PROTOPAM CHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PROTOPAM CHLORIDE (PROTOPAM CHLORIDE).
Reactivates acetylcholinesterase inhibited by organophosphate poisoning by binding to the organophosphate moiety, forming a complex that undergoes hydrolysis to regenerate active enzyme. Also has a direct neutralization effect on certain organophosphates.
| Metabolism | Hepatic metabolism (minor); primarily excreted unchanged in urine. |
| Excretion | Renal excretion is the primary route, with 80-90% of a dose eliminated unchanged in urine within 30 minutes; the remainder is metabolized and excreted fecally. |
| Half-life | Terminal elimination half-life is approximately 1.7 hours in adults. In renal impairment, half-life may be prolonged up to 6 hours, requiring dose adjustment. |
| Protein binding | Minimal protein binding, less than 10%, primarily to albumin. |
| Volume of Distribution | Volume of distribution is approximately 0.5-0.8 L/kg, suggesting distribution primarily into extracellular fluid. |
| Bioavailability | Intramuscular bioavailability is approximately 80-90% compared to intravenous. |
| Onset of Action | Intravenous: onset within 5-15 minutes; intramuscular: onset within 15-30 minutes. |
| Duration of Action | Duration is 1-2 hours, but repeated doses may be needed due to short half-life and potential re-inhibition of acetylcholinesterase. |
1-2 g IV over 15-30 minutes, may repeat after 1 hour if muscle weakness persists, then every 3-8 hours as needed for 24-48 hours.
| Dosage form | INJECTABLE |
| Renal impairment | No specific GFR-based guidelines; use with caution in severe renal impairment (CrCl < 30 mL/min) and consider dose reduction or extended intervals based on clinical response. |
| Liver impairment | No specific Child-Pugh based modifications; monitor for adverse effects in hepatic impairment. |
| Pediatric use | 20-50 mg/kg IV over 30 minutes, maximum 2 g per dose; may repeat after 1 hour, then every 3-8 hours as needed. |
| Geriatric use | No specific dose adjustment; monitor renal function and consider lower initial doses due to age-related decreased renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PROTOPAM CHLORIDE (PROTOPAM CHLORIDE).
| Breastfeeding | Pralidoxime is excreted into breast milk in low concentrations; M/P ratio is not established. Short-term treatment of acute poisoning is compatible with breastfeeding if necessary. Avoid nursing during maternal treatment due to potential infant exposure; consider pumping and discarding milk for duration of therapy. |
| Teratogenic Risk | Pralidoxime chloride is a quaternary ammonium oxime. Available animal studies are insufficient to determine teratogenic risk. In humans, no adequate controlled studies exist. First trimester risk cannot be excluded. Second and third trimester use is indicated for treatment of organophosphate poisoning, where benefit outweighs unknown fetal risk. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to pralidoxime; terminal organophosphate poisoning (ineffective if acetylcholinesterase has undergone aging).
| Precautions | Should be used in conjunction with atropine for organophosphate poisoning; monitor for signs of organophosphate toxicity recurrence; use with caution in patients with myasthenia gravis; rapid intravenous administration may cause laryngospasm, muscle rigidity, or transient neuromuscular blockade. |
Loading safety data…
| Fetal Monitoring | Monitor maternal vital signs, oxygen saturation, and cardiac rhythm continuously during infusion. Assess for signs of organophosphate toxicity and response to therapy. Fetal heart rate monitoring if viable. Observe for maternal adverse effects: hypertension, tachycardia, muscle rigidity, laryngospasm. In severe poisoning, monitor maternal respiratory status and prepare for intubation. |
| Fertility Effects | No human data on fertility effects. Animal studies have not been conducted. Pralidoxime is used acutely in life-threatening poisoning, and its effect on fertility is likely negligible given short duration of therapy. |