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Clinical pharmacy 2024/2025 Level 3 Pharm D Pharmacology 1 (PO 502)

irreversible cholinesterase inhibitors (OPC)

Examples ➔ Di isopropyl fluorophosphate (DFP), Sarine (war gas), parathion and
Malathion (insecticide).

Actions Treatment

If injected or inhaled ➔ peripheral 1) Remove toxic agent.
muscarinic, nicotinic effects & CNS 2) Atropine, every 30 min I.M. ➔

effects. until muscarinic symptoms disappear
1) Peripheral ➔ Muscle fasciculation, or full atropinization ➔ Dryness of
miosis (pinpoint), salivation, sweating, mouth & mydriasis after miosis.

cramps, abdominal & respiratory distress. 3) 2-PAM 1-2 gm repeated every 20-30
2) CNS effects ➔ Anxiety, restlessness & min I.V. (as soon as possible to avoid
convulsion. aging)

3) Neurotoxicity (with sarine) ➔ long 4) Remove secretions to allow free air
lasting with varying degree of severity passage & artificial respiration.
➔ no successful antidote & physiotherapy 5) Diazepam to control convulsion.

is the only treatment. 6) Gastric lavage if taken orally.

Reactivation of the inhibited enzyme: ➔ within 6 hrs.
 Hydroxylamine & oxime ➔ attach to the anionic site of phosphorylated enzyme ➔

 rate of hydrolysis of the ester bond at the esteratic site ➔ reactivator or
regenerator of the enzyme ➔ e.g. pyridine-2-aldoxime-methiodide (2 PAM).

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