What is the treatment for organophosphorus poisoning?

From the Guidelines

The treatment for organophosphorus poisoning requires immediate medical attention, with atropine administration being the cornerstone of treatment, as evidenced by the 2023 American Heart Association guidelines 1. The primary goal of treatment is to counteract the effects of organophosphates, which inhibit acetylcholinesterase and cause excessive acetylcholine accumulation.

• Decontamination should be performed by removing contaminated clothing and washing the skin with soap and water, as recommended by the 2023 American Heart Association guidelines 1.
• Atropine should be administered at a dose of 1-5 mg intravenously every 5-10 minutes until signs of atropinization appear, then continued as needed, with the initial dose often being doubled every 5 minutes until full atropinization is achieved 1.
• Oximes, particularly pralidoxime (2-PAM), may be considered as an adjunctive treatment, although the evidence for its use is not as strong as that for atropine 1.
• Benzodiazepines such as diazepam may be administered to control seizures and reduce neurological damage, as recommended by the 2023 American Heart Association guidelines 1.
• Supportive care, including airway management, oxygen supplementation, and mechanical ventilation, may be necessary in severe cases, with early endotracheal intubation being recommended for life-threatening organophosphate or carbamate poisoning 1. The use of personal protective equipment is also crucial when caring for patients with organophosphate or carbamate exposure, as highlighted by the 2003 study on protective equipment for health care facility decontamination personnel 1. Overall, prompt treatment with atropine and supportive care is crucial to prevent deterioration to respiratory and cardiac arrest, and to improve outcomes in patients with organophosphorus poisoning 1.

From the FDA Drug Label

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 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 organophosphorus 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 signs of poisoning recur 2
• 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 Overview

The treatment for organophosphorus poisoning typically involves a combination of medications and supportive care.

• Atropine is commonly used to counteract the muscarinic effects of organophosphorus poisoning, such as bronchial hypersecretion and respiratory failure 3, 4, 5.
• Oximes, such as pralidoxime, may be used to reactivate acetylcholinesterase, an enzyme that is inhibited by organophosphorus compounds 3, 6, 7.
• Benzodiazepines, such as diazepam, may be used to control seizures and agitation 3, 7.
• Supportive care, including respiratory support, fluids, and cardiac monitoring, is also crucial in the management of organophosphorus poisoning 3, 4, 5.

Medication Administration

The administration of these medications can vary depending on the severity of the poisoning and the patient's response to treatment.

• Atropine may be administered intravenously, with the dose titrated to effect 4.
• Pralidoxime may be administered as a continuous infusion, particularly in cases where the extent of chemical exposure or quantity of chemical ingested is unknown 6.
• The duration and dosage of atropine and oximes may need to be adjusted based on the patient's clinical response and serum acetylcholinesterase levels 5.

Novel Approaches

Several novel approaches to the treatment of organophosphorus poisoning are being explored, including the use of bioscavengers, alkalinization of blood plasma/serum, and the development of new oximes 7.

• These approaches aim to improve the efficacy and safety of treatment for organophosphorus poisoning, particularly in cases where standard therapies are ineffective.

Important Considerations

The management of organophosphorus poisoning requires careful consideration of several factors, including the severity of the poisoning, the patient's clinical response to treatment, and the potential for respiratory failure 3, 5.

• Early recognition and treatment of organophosphorus poisoning are critical to improving outcomes and reducing mortality 3, 5.
• The use of grading systems, such as the system developed by Bardin et al, can help physicians to facilitate the recognition of seriously poisoned subjects and permit their early admission to an intensive care unit 5.