What are the symptoms and treatment of Organophosphate (OP) overdose?

From the Guidelines

Organophosphate overdose requires immediate treatment with atropine and pralidoxime to prevent deterioration to respiratory and cardiac arrest. The symptoms of organophosphate overdose include parasympathetic excess (bradycardia, bronchospasm, bronchorrhea, miosis, hypersalivation, lacrimation, urination, diarrhea, vomiting, diaphoresis), nicotinic excess (tachycardia, mydriasis, fasciculations progressing to depolarizing neuromuscular blockade and paralysis), and CNS effects (altered mental status, central apnea, seizures) 1.

Treatment Approach

The cornerstones of treatment include:

• Decontamination: dermal decontamination through removal of contaminated clothing and copious irrigation with soap and water, performed by people wearing protective barriers, helps prevent further absorption and prevents contamination of caregivers and the care environment 1.
• Atropine: blocks parasympathetic overstimulation, mitigating bronchorrhea, bradycardia, bronchospasm, and CNS effects, and should be given immediately for severe poisoning, such as bronchospasm, bronchorrhea, seizures, or significant bradycardia 1.
• Benzodiazepines: are recommended to treat seizures and agitation in the setting of organophosphate or carbamate poisoning 1.
• Pralidoxime: the use of pralidoxime is reasonable for organophosphate poisoning, and should be administered at 1-2g IV over 15-30 minutes for adults or 20-50mg/kg for children, followed by continuous infusion of 500mg/hour (adults) or 10-20mg/kg/hour (children) for 24-48 hours.

Key Considerations

• Early and effective treatment is crucial to prevent deterioration to respiratory and cardiac arrest.
• Supportive care includes airway management, oxygen, and seizure control with benzodiazepines if needed.
• Organophosphates inhibit acetylcholinesterase, causing acetylcholine accumulation at synapses, which leads to the classic symptoms remembered by "SLUDGE" (Salivation, Lacrimation, Urination, Defecation, GI upset, Emesis) plus respiratory depression and CNS effects.
• Atropine blocks muscarinic effects while pralidoxime reactivates acetylcholinesterase if given early enough, before "aging" of the enzyme-toxin complex occurs.

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. Symptoms Of Nerve Agent And Insecticide Poisoning These symptoms include the following: MILD symptoms: • Blurred vision and sore eyes • Teary eyes* • Runny nose* • Increased salivation such as sudden drooling* • Chest tightness or difficulty breathing • Tremors throughout the body or muscular twitching • Nausea and vomiting • Involuntary respiratory secretions SEVERE symptoms: • Strange or confused behavior • Severe difficulty breathing or respiratory secretions • Severe muscular twitching and general weakness** • Involuntary urination and defecation* • Convulsions • Unconsciousness

The symptoms of Organophosphate (OP) overdose include mild symptoms such as blurred vision, teary eyes, runny nose, increased salivation, chest tightness, tremors, nausea, and vomiting, and severe symptoms such as strange behavior, severe difficulty breathing, severe muscular twitching, involuntary urination and defecation, convulsions, and unconsciousness. Treatment of OP overdose should include general supportive care, atropinization, and decontamination, in addition to the use of pralidoxime chloride 2. Atropine should be given as soon as possible after hypoxemia is improved, and some degree of atropinization should be maintained for at least 48 hours 2. Pralidoxime chloride may be administered after the effects of atropine become apparent, with an initial dose of 1000 to 2000 mg, preferably as an infusion in 100 mL of normal saline, over a 15- to 30-minute period 2.

From the Research

Symptoms of Organophosphate (OP) Overdose

• The symptoms of OP overdose include vomiting, epigastric pain, severe salivation, diaphoresis, encephalopathy, meiosis, change in mental status, hypersalivation, fasciculations, and respiratory failure 3, 4, 5
• Intermediate syndrome, which is a condition that occurs after acute OP poisoning, can also be observed in some patients 5
• Other complications that may occur include aspiration pneumonia, urinary system infection, convulsion, and septic shock 5

Treatment of Organophosphate (OP) Overdose

• The treatment of OP overdose consists of intravenous atropine and oximes, as well as supportive care such as gastric lavage, administration of activated charcoal, and mechanical ventilation if necessary 3, 4, 5, 6
• High-dose atropine therapy may be necessary in some cases, and the dose can be titrated based on the patient's response 3, 6
• The use of pralidoxime (PAM) is also recommended, although its availability may be limited in some cases 5, 6
• Novel treatment approaches such as hemofiltration and lipid solutions have also been studied, although their effectiveness is still being researched 6
• Early recognition and treatment of respiratory failure is crucial in reducing mortality rates among patients with OP poisoning 5