NEOSTIGMINE

Pharmacokinetics

This drug is poorly absorbed from the gastro intestinal tract and is poorly distributed throughout the body; it cannot pass the blood brain barrier.

Pharmacodynamics

Just like physostigmine, it inhibits cholinesterase enzyme; but unlike physostigmine, it has a direct nicotinic action on skeletal muscles.

Indications

• Myasthenia gravis
• Paralytic Ileus
• Reversal of effect of muscle relaxants, e.g. tubocurarine
• Post operative urine retention

Organophosphates such as echothiophate, isofluorophate, etc. combine with cholinesterase irreversibly and thus hydrolysis is very slow.

They may be used in glaucoma. Other organophosphates like parathion and malathion are used as insecticides. Poisoning with organophosphates is an important cause of morbidity and mortality all over the world. It usually results from:

• Occupational exposure as in persons engaged in spraying insecticides,
  • Accidental exposure, and

• Ingestion of any of these compounds with suicidal intent.