Carbamazepine Flashcards
Which of the following two drugs is more toxic - oxycarbazepine or carbamazepine?
Oxy is much less toxic
Discuss the dose-related symptoms of carbamazepine toxicity.
20-50 mg/kg: mild/mod CNS and anticholinergic effects. >50 mg/kg: fluctuating mental status, progression to coma, hypotension, cardiotoxity in higher doses
What can be anticipated with larger doses of carbamazepine?
Anticholinergic effects may be prominent PRIOR to development of coma
Discuss carbamazepine overdose in pregnancy and children.
Pregnancy: teratotoxic. Children: >400 mg is enough to cause significant intoxication
How does carbamazepine work?
Similar in structure to TCAs, inhibits INACTIVATED sodium channels –> preventing further action potentials. Also blocks NA reuptake and is an antagonist at muscarinic, nicotinic and NMDA central adenosine receptors.
What is important to remember about absorption of carbamazepine in overdose?
Ileus secondary to anticholinergic effects may result in ongoing absorption for several days
What are the symptoms of carbamazepine toxicity?
CNS: nystagmus, atasia, sedation, ophthalmoplegia, myoclonus. Anticholinergic: urinary retention, tachy, dry mouth. Others in high doses: coma, agitation, seizures, hypotension, conduction abnormalities + dysrhythmias
What ECG changes would you anticipate with a large carbamazepine overdose?
> 50 mg/kg –> evidence of sodium channel blockade (1st degree HB + increased QRS)
Discuss decontamination and elimination with carbamazepine.
Decontamination: activated charcoal <50 mg/kg, usually only if the patient is intubated. Enhanced elimination: multiple-dose activated charcoal in intubated patients. Haemodialysis/filtration works well as well.
What is a quick way in which patients which a suspected carbamazepine overdose (especially with children) can be discharged?
Undetectable serum carbamazepine level any time after the first hour excludes ingestion
