Organophosphate poisoning

Overview of organophosphate poisoning

Overview

Chemical structure of a phosphate group.

Organophosphate poisoning is a serious medical condition resulting from the exposure to organophosphate chemicals, which are commonly used as pesticides. These compounds inhibit the enzyme acetylcholinesterase, leading to an accumulation of acetylcholine in the body and causing a range of symptoms.

Pathophysiology

Organophosphates exert their toxic effects by phosphorylating the serine hydroxyl group in the active site of acetylcholinesterase. This prevents the breakdown of acetylcholine, resulting in continuous stimulation of muscarinic and nicotinic receptors. The overstimulation of these receptors leads to the characteristic symptoms of organophosphate poisoning.

Symptoms

The symptoms of organophosphate poisoning can be divided into muscarinic, nicotinic, and central nervous system effects:

• Muscarinic effects: These include miosis (constricted pupils), excessive salivation, lacrimation, urination, diarrhea, gastrointestinal distress, and emesis (vomiting).
• Nicotinic effects: These include muscle twitching, weakness, and paralysis.
• Central nervous system effects: These include anxiety, confusion, ataxia, seizures, and coma.

Diagnosis

Diagnosis of organophosphate poisoning is primarily clinical, based on the history of exposure and the presence of characteristic symptoms. Laboratory tests can confirm the diagnosis by measuring the activity of acetylcholinesterase in the blood.

Treatment

The treatment of organophosphate poisoning involves several steps:

1. Decontamination: Remove contaminated clothing and wash the skin thoroughly to prevent further absorption of the chemical. 2. Supportive care: Maintain airway, breathing, and circulation. Administer oxygen and intravenous fluids as needed. 3. Antidotes: Administer atropine, an antimuscarinic agent, to counteract the muscarinic effects. Pralidoxime (2-PAM) can be used to reactivate acetylcholinesterase if given early. 4. Seizure control: Use benzodiazepines to manage seizures.

Prevention

Preventing organophosphate poisoning involves proper handling and use of pesticides, including wearing protective clothing and equipment, following safety guidelines, and ensuring proper ventilation when using these chemicals.

Related pages

• Acetylcholinesterase
• Pesticide poisoning
• Nerve agent