Overview
DESCRIPTION Chemical name: 2-formyl-1-methylpyridinium chloride oxime. Available in the United States as PROTOPAM Chloride for Injection (PROTOPAM Chloride), pralidoxime chloride is frequently referred to as 2-PAM Chloride. Structural formula: C7H9CIN2O M.W. 172.61 Pralidoxime chloride occurs as an odorless, white, nonhygroscopic, crystalline powder which is soluble in water.
Mechanism of Action
CLINICAL PHARMACOLOGY The principal action of pralidoxime chloride is to reactivate cholinesterase (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 critical effect in relieving paralysis of the muscles of respiration.
Indications
- INDICATIONS AND USAGE PROTOPAM Chloride 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 PROTOPAM Chloride are muscle weakness and respiratory depression. In severe poisoning, respiratory depression may be due to muscle weakness.
Common Doses
- 4 mg
- 20 mg
- 2000 mg
- 100 mL
Dosage
DOSAGE AND ADMINISTRATION Organophosphate Poisoning Treatment should include general supportive care, atropinization, and decontamination, in addition to the use of PROTOPAM Chloride. Treatment is most effective if initiated immediately after poisoning. Administration of PROTOPAM Chloride should 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 Chloride is given more than 36 hours after termination of exposure to the poison.
Contraindications
- CONTRAINDICATIONS There are no known absolute contraindications for the use of PROTOPAM Chloride (see PRECAUTIONS, Drug Interactions and DOSAGE AND ADMINISTRATION ). Relative contraindications include known hypersensitivity to the drug and other situations in which the risk of its use clearly outweighs possible benefit.
Side Effects
- ADVERSE REACTIONS Forty to 60 minutes after intramuscular injection, mild to moderate pain may be experienced at the site of injection. 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.
Interactions
- Drug Interactions 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. The following precautions should be kept in mind in the treatment of anticholinesterase poisoning, although they do not bear directly on the use of pralidoxime chloride: since barbiturates are potentiated by the...