Lecture Note on Organophosphorus Compounds Poisoning.

Organophosphorus Compounds Poisoning.

• Organophosphorus compounds are commonly used as "Insecticides." the common examples are, Malathion, Parathion, Diazinon, Fenthione etc.
  
• MOA: They act by irreversible inhibition of enzyme "Acetyl Choline Esterase", by causing permanent destruction of the enzyme structure the compounds set free Ach (Acetyl Choline) causing poisoning.
• Most of the times the poisoning is fatal one leading to death.

Modes: 

1. Physical Contact.
2. Inhalation.
3. Ingestion.

Causes:

1. Occupational: Persons coming in contact with insecticides during their daily work. e.g. Farmers, Factory labors.
   
2. Accidental: Accidental consumption or inhalation of household insecticides.
3. Intentional: Homicide or Suicide.

Symptoms:

The OPCs increase concentration of Ach and hence their effects can be categorized into two Muscarinic Effects and Nicotinic Effects.
Here we are going to see effects for ingestion, inhalation and contact poisoning.

A) Ingestion Muscarinic Symptoms: 

1. Bronchospasm(wheezing) • 
2.   Muscle weakness•  
3. Bronchorrhoea • 
4.   Fasciculation• 
5.   Productive cough• 
6.   Dyspnoea • 
7.   Paralysis• 
8.   Hypotension • 
9.   Muscle twitching•  
10. Bradycardia• 
11.   Cardiac arrhythmia• 
12.   Diarrhea• 
13.   Vomiting• 
14.   Salaivation• 
15.   Tenesmus• 
16.   Miosis• 
    
17.   Lacrimation•  
18. Blurred vision

B) Inhalation Eye contact Symptoms.

1. Cough
2. Irritation
3. Difficulty in breathing
4. Pain
5. Bronchitis
6. Lacrimation
7. Pneumonia
8. Miosis
9. Blurring vision.

Treatment:

• Prompt hospitalization.
• Cleaning of organs came in contact with the poison with soap. 
• Cleaning of nasal pharyngeal secretions by hand or by using suction pathway to clear the obstruction in airway.
• Patient is kept in prone position to aid breathing.
• Artificial respiration (Endotracheal Intubation) is given immediately to cover respiratory depression which is major cause of death during OPC poisoning.
  
• Gastric lavage if poison is ingested, within two hours to remove unabsorbed poison.
  
• Antidote: "Atropine" is given 1.8-3.0 mg in fast iv bolus. ( Dose is titrated after checking the major symptoms after 3 to 5 minutes.
  
• Enzyme Reactivators: Pralidoxime,/ Obidoxime (Reactivate is phosphorylated enzyme) is given to reactivate the enzyme Ach Esterase.
  
  
  
  
• Symptomatic treatment.