Pralidoxime Chloride

Indications

Pralidoxime Chloride is used for: Organophosphorous poisoning, Overdoses of anticholinesterase drugs used in the treatment of, myasthenia gravis.

Adult Dose

Organophosphorous Poisoning For IV Infusion: Adults: 1-2 g IV as 15-30 min infusion, repeat a second dose of 1 g to 2 g may be indicated after about one hour if muscle weakness has not been relieved. Additional doses may be given every 10-12 hours if muscle weakness persists. OR Use with atropine, which affects muscarinic receptors; pralidoxime's actions most striking at nicotonic sites (increase muscle strength 10-40 min) For IV Injection: For fluid restricted patient 1 g, should be slowly given (over not less than 5 minutes) by IV injection, as 50 mg/ml solution in normal saline (e.g. 1 g in 20 ml). IM: 600 mg IM x3 doses; administer each dose 15 minutes apart for mild symptoms, or in rapid succession for severe symptoms Acetylcholinesterase Inhibitor Toxicity Initial: 30 mg/kg IV (IM, SC if no IV access) over 20 min 4-8 mg/kg/hr IV infusion

Child Dose

Organophosphorous Poisoning For IV Infusion: Children > 16 years of age: 1-2 g IV as 15-30 min infusion, repeat a second dose of 1 g to 2 g may be indicated after about one hour if muscle weakness has not been relieved. Additional doses may be given every 10-12 hours if muscle weakness persists. OR Use with atropine, which affects muscarinic receptors; pralidoxime's actions most striking at nicotonic sites (increase muscle strength 10-40 min) For IV Injection: For fluid restricted patient 1 g, should be slowly given (over not less than 5 minutes) by IV injection, as 50 mg/ml solution in normal saline (e.g. 1 g in 20 ml). Children < 16 years of age: Loading dose: 20-50 mg/kg (maximum: 2000 mg/dose); Maintenance infusion: 10-20 mg/kg/hour; alternatively, a repeat bolus of 20-50 mg/kg (maximum 2000 mg/dose) may be administered after 1 hour and repeated every 10-12 hours thereafter, as needed. IM administration <40 kg: 15 mg/kg/dose IM x3 doses 40 kg or greater: Administer as in adults; 600 mg/dose IM x3 doses

Renal Dose

Renal Impairment: Reduce dose

Administration

IV Preparation Reconstitute by adding 20 mL SWI to the 1 g vial to provide a 50 mg/mL solution (do not use preservative-containing solutions) IV Administration For infusion, dilute required amount of reconstituted solution to 100 mL with NS Infuse over 15-30 min May also be given as 5 min slow IVP IM Administration 1 g vial contents may be reconstituted by adding 3 mL SWI or NS to provide a 300 mg/mL solution

Contra Indications

Carbamate pesticide poisoning, hypersensitivity.

Precautions

The following precautions should be kept in mind in the treatment of acetylcholinesterase poisoning, although they do not bear directly on the use of Pralidoxime Chloride, since barbiturates are potentiated by the anticholinesterases, they should be used cautiously in the treatment of convulsion; morphine, theophylline, aminophylline, succinylcholine, reserpine and phenothiazine-type tranquilizers should be avoided in patients with organophosphate poisoning. Prolonged paralysis has been reported with patients when succinylcholine is given with drugs having anticholinesterase activity; therefore it should be used with cautions. Pregnancy, lactation.

Pregnancy-Lactation

Pregnancy Category: C

Interactions

Adverse Effects

Side effects of Pralidoxime Chloride : Drowsiness, dizziness, visual disturbances, nausea, tachycardia, headache, hyperventilation and muscle weakness. Potentially Fatal: Rapid admin causes tachycardia, laryngospasm and rigidity. Large doses cause neuromuscular blockade.

Mechanism of Action

Pralidoxime reactivates cholinesterase outside the CNS which has been inactivated by phosphorylation due to organophosphate pesticide exposure-resulting. This leads to the destruction of acetylcholine at the neuromuscular junction thus relieving muscle paralysis. It also removes the phosphyl group from the active site of inactivated enzyme which is dependent on the nature of the phosphyl group.