From the Guidelines
The treatment for parathion poisoning requires immediate medical attention, including administration of atropine and pralidoxime, decontamination, and supportive care to manage the cholinergic crisis and prevent long-term effects. The management of parathion poisoning involves a multi-faceted approach, prioritizing prevention of additional exposure, removal of the poison, provision of supportive care, and administration of antidotes to reverse the effects of the poison on its molecular target 1.
Key Interventions
- Atropine should be administered intravenously at 2-5 mg every 5-10 minutes until signs of atropinization appear, followed by maintenance dosing.
- Pralidoxime (2-PAM) should be given at 1-2 g IV initially, followed by 500 mg every 6-8 hours or as a continuous infusion at 500 mg/hour to reactivate acetylcholinesterase.
- Decontamination is crucial, including removal of contaminated clothing, washing the skin thoroughly with soap and water, and performing gastric lavage if ingestion occurred within 1 hour.
Supportive Care
- Maintaining airway, breathing, and circulation is essential, with possible need for mechanical ventilation.
- Seizure control with benzodiazepines may be necessary.
- Continuous cardiac monitoring is essential as dysrhythmias may occur.
- Treatment may need to continue for days as parathion can have prolonged effects due to fat storage and slow release. According to the 2023 American Heart Association guidelines, timely and effective supportive care, including airway management, hemodynamic support, and correction of critical vital sign and metabolic derangements, is essential to the care of the poisoned patient and takes priority over identification of the toxicant and antidotal therapy 1.
From the FDA Drug Label
Treatment should include general supportive care, atropinization, and decontamination, in addition to the use of PROTOPAM Chloride. 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 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 PROTOPAM Chloride may be needed every three to eight hours In effect, the patient should be “titrated” with PROTOPAM Chloride as 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 atropine-induced 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.
The treatment for parathion poisoning includes:
- General supportive care
- Atropinization: atropine should be given as soon as possible after hypoxemia is improved, in doses of 2 to 4 mg, repeated at 5- to 10-minute intervals until full atropinization or signs of atropine toxicity appear
- Decontamination: clothing should be removed and the hair and skin washed thoroughly with sodium bicarbonate or alcohol as soon as possible
- Administration of PROTOPAM Chloride: should be carried out slowly and preferably by infusion, with additional doses needed every three to eight hours if the poison has been ingested
- 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 2
From the Research
Treatment for Parathion Poisoning
The treatment for parathion poisoning involves several key components, including:
- Atropine administration to counteract cholinergic symptoms 3, 4, 5
- Oximes, such as obidoxime or pralidoxime (2-PAM), to reactivate acetylcholinesterase 3, 4, 5
- Benzodiazepines for seizure control 3
- Supportive care, including decontamination, cardiac monitoring, and respiratory support as needed 3, 4, 5
Pharmacokinetics and Toxicokinetics
The pharmacokinetics and toxicokinetics of parathion poisoning are complex and can vary widely among individuals 4. Key factors include:
- Absorption: Parathion can be absorbed through the gastrointestinal tract, with absorption sometimes retarded up to 5 days 4
- Distribution: The volume of distribution at steady-state (Vdss) of parathion is around 20 L/kg, with high concentrations found in fat tissue 4
- Elimination: The elimination half-life of parathion can range from 17.9 to 30.4 hours, depending on the individual and the specific compound 3, 4
Clinical Management
Clinical management of parathion poisoning requires close monitoring and aggressive treatment, including:
- Aggressive atropinisation to achieve dry mucous membranes, no bronchoconstriction, and no bradycardia 4, 5
- Continuous pralidoxime (2-PAM) infusion to reactivate acetylcholinesterase 5
- Mechanical ventilation and respiratory support as needed 5
- Monitoring for potential complications, including myocardial infarction 6