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2. Drugs acting on Autonomic nervous system

Organophosphate Poisoning and Management

Causes of Poisoning

  1. occupational poisoning
  2. homicidal
  3. accidental

In the battle field, soldiers are at risk of poisoning, so they are treated with physostigmine before they are sent.

 Manifestations of Poisoning

Muscarinic:

CNS -CNS stimulant effect leading to tremors, fatigue, drowsiness, confusion,

Eye -Meiosis, blurring of vision, increased lacrimation

GIT -Increased salivation, nausea, vomiting, diarrhea,

Respiratory system -Respiratory distress, increased bronchial secretions

Urinary tract -Excessive urination

Nicotinic:

Skeletal muscle depolarizing blocking type of effect by which fasciculations may occur. The muscle strength decreases.

Management Of Poisoning:

I. General Measures:

The person is quickly removed from the area of contamination. The clothing is removed. Body is washed with sodium bicarbonate. The person is placed in prone position, with mandible elevated. In case of hypotension, IV fluid is administered. If required endotracheal intubation may be performed. Gastric lavage may be done.

II. Specific Treatment;

MANAGEMENT OF CONVULSIONS

Diazepam                          5 – 10 mg I/V

Thiopentone Sodium             2.5%   I/V

MANAGEMENT OF CHOLINERGIC MUSCRINIC EFFECTS:-

Atropine                           2-4  mg I/V or  I/M

MANAGEMENT OF ENZYME INHIBITION:-

Use of oximes.

Oximes
(Acetylcholine Esterase Reactivators)

1. Paralidoxime (1-2 g I/V) (cannot cross BBB)

2. Obidoxime (3.6 mg /kg body weight I/V)

3. Diacetyl monoxime (1.2 g I/V) (DAM)

CNS effects are also reversed by Obidoxime and Diacetyl monoxime.

4. Trimedoxime bromide

Phosphate bond is produced when organophosphate compounds bind active site. Oximes bind anionic site of enzyme and have a high affinity for phosphorus atom, thus enzyme phosphate complex is produced and the active site is free once again. This is only possible if treatment started within 36 hours. Very high doses of oximes have to administered to revert the effects.

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