management of op poisoning-definitive treatment

8
DEFINITIVE TREATMENT OF ORGANOPHOSPHORUS POISONING

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Page 1: Management of op poisoning-definitive treatment

DEFINITIVE TREATMENTOF

ORGANOPHOSPHORUS POISONING

Page 2: Management of op poisoning-definitive treatment

Atropine

Cholinesterase reactivators (Oximes)

Drugs used in definitive treatment:

Page 3: Management of op poisoning-definitive treatment

(a)ATROPINE

Anti cholinergic drug.

Objective : To block the muscarinic receptors until the organophosphate is metabolised away from the body.

Atropine : Adult dose : 2-5mg i.v. repeated every 5 min doubling the initial dose.

Children : 0.05-0.1mg/kg

Given till signs of atropinization appear.

Continued treatment: maintenance dose (30% of atropinization dose) for 1-2 weeks.

Page 4: Management of op poisoning-definitive treatment

(b)CHOLINESTERASE REACTIVATORS

Oximes are used to restore neuromuscular transmission.

If more reactive OH groups in the form of oximes (Generic formula R-CH=N-OH) are provided reactivation occurs more faster.

Eg: Pralidoxime ( 2-PAM)

Page 5: Management of op poisoning-definitive treatment

Action of Pralidoxime (2-PAM)Attaches to the anionic site of the enzyme.Oxime end reacts with the phosphorus atom

attached to the esteratic site.Oxime-phosphonate form and diffuse away.Reactivated ChE remain. Treatment should be started within 24 hours

before the phosphorylated enzyme undergoes ‘Aging’ and become resistant to hydrolysis.

Page 6: Management of op poisoning-definitive treatment

It is ineffective to carbamate poisoning as in that case the anionic site of the enzyme is not free.

It is rather contraindicated because it has weak anti-ChE activity of its own.

Page 7: Management of op poisoning-definitive treatment

Injected i.v. slowly in a dose of 1-2g.

Doses may be repeated according to need.

Use of oximes in OP poisoning is secondary to that of Atropine.

Page 8: Management of op poisoning-definitive treatment

OTHER OXIMES:

Obidoxime: more potent than pralidoxime

Diacetyl-monoxime (DAM): Lipophilic; so if the OP poisoning symptoms are more central DAM is used as it can cross the blood brain barrier.