It is indicated as an antidote: (1) In the treatment of poisoning due to those pesticides and chemicals (e.g.,nerve agents) of the organophosphate class which have anticholinesterase activity and (2) In the control of overdosage by anticholinesterase drugs used in the treatment of myasthenia gravis. The principal indications for the use of Itare muscle weakness and respiratory depression. In severe poisoning,respiratory depression may be due to muscle weakness.
Pralidoxime Chloride is an acetylcholinesterase reactivator. The principal action of Pralidoxime Chloride is to reactivate acetylcholinesterase (mainly outside of the central nervous system) which has been inactivated by phosphorylation due to an organophosphate pesticide or related compound. The destruction of accumulated acetylcholine can then proceed, and neuromuscular junctions will again function normally. Pralidoxime Chloride also slows the process of "aging" of phosphorylated cholinesterase to a nonreactivatable form, and detoxifies certain organophosphates by direct chemical reaction. The drug has its most certain effect in relieving paralysis of the muscles of respiration. Atropine is always required concomitantly to block the effect of accumulated acetylcholine at this site. Pharmacokinetic properties: Minimum therapeutic concentration of Pralidoxime Chloride in plasma (4 µg/ml) may be reached in about 16 minutes after injection of 600 mg Pralidoxime Chloride. The drug is rapidly excreted in urine partly unchanged and partly as metabolite produced by the liver.
Treatment should include general supportive care,atropinization,and decontamination,in addition to the use of PROTOPAM. Treatment is most effective if initiated immediately after poisoning. Administration of Itshould be carried out slowly and, preferably,by infusion. If intravenous administration is not feasible,intramuscular or subcutaneous injection should be used. Generally,little is accomplished if PROTOPAM is given more than 36 hours after termination of exposure to the poison. When the poison has been ingested,it is particularly important to take into account the likelihood of continuing absorption from the lower bowel since this constitutes new exposure and fatal relapses have been reported after initial improvement. In such cases,additional doses of Itmay be needed every three to eight hours. In effect,the patient should be ?titrated? with Itas long as signs of poisoning recur. As in all cases of organophosphate poisoning,care should be taken to keep the patient under observation for at least 48 to 72 hours. If dermal exposure has occurred,clothing should be removed and the hair and skin washed thoroughly with sodium bicarbonate or alcohol as soon as possible. Supportive care,including airway management,respiratory and cardiovascular support, correction of metabolic abnormalities,and seizure control,may be necessary in cases of severe organophosphate poisoning. Atropine should be given as soon as possible after hypoxemia is improved. Atropine should not be given in the presence of significant hypoxia due to the risk of atropineinduced ventricular fibrillation. In adults,atropine may be given intravenously in doses of 2 to 4 mg. This should be repeated at 5- to 10-minute intervals until full atropinization (secretions are inhibited) or signs of atropine toxicity appear (delirium,hyperthermia, muscle twitching). Some degree of atropinization should be maintained for at least 48 hours,and until any depressed blood cholinesterase activity is reversed. Use of morphine,theophylline,aminophylline,reserpine,and phenothiazine-type tranquilizers should be avoided in patients with organophosphate poisoning Prolonged paralysis has been reported in patients when succinylcholine is given with drugs having anticholinesterase activity; therefore,it should be used with caution.
When atropine and Pralidoxime Chloride are used together the signs of atropinization (flushing, mydriasis, tachycardia, dryness of the mouth and nose) may occur earlier than might be expected when atropine is used alone. This is especially true if the total dose of atropine has been large and the administration of Pralidoxime Chloride has been delayed.
There are no known absolute contraindications for the use of It Relative contraindications include known hypersensitivity to the drug and other situations in which the risk of its use clearly outweighs possible benefit.
Pralidoxime chloride may cause blurred vision,diplopia and impaired accommodation, dizziness,headache,drowsiness,nausea,tachycardia,increased systolic and diastolic blood pressure,hyperventilation,and muscular weakness when given parenterally to normal volunteers who have not been exposed to anticholinesterase poisons
Pregnancy Teratogenic Effects?Pregnancy Category C Animal reproduction studies have not been conducted with pralidoxime chloride. It is also not known whether pralidoxime chloride can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Pralidoxime chloride should be given to a pregnant woman only if clearly needed. Nursing Mothers It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk,caution should be exercised when pralidoxime chloride is administered to a nursing woman.
Observed in normal subjects only: Dizziness, blurred vision, diplopia, headache, impaired accommodation, nausea, slight tachycardia. Treatment of overdose is artificial respiration and other supportive therapy should be administered as needed.
Store in a cool and dry place, away from light. Keep out of the reach of children.
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