Updated 8/2001

Type of product:

Anticonvulsant, also used to treat trigeminal neuralgia.

Ingredients:

Carbamazepine
Tablet - 100 mg, 200 mg, 400 mg
Liquid - 100 mg/5 mL
Chewtabs - 100 mg, 200 mg
Retard - 200 mg, 400 mg sustained release
Suppositories - 125 mg , 250 mg

 

Toxicity:

Features of poisoning correlate poorly with doses stated to have been ingested. Patients on carbamazepine therapy may have greater tolerance. The plasma half-life is 30-40 hours.

Carbamazepine - features and management

Features:

Dysarthria, ataxia, nystagmus, drowsiness and violent behaviour with tachycardia, dilated pupils and hyperreflexia.

More severe poisoning leads to coma, respiratory depression and convulsions.

ECG abnormalities similar to those seen in tricyclic antidepressant overdosage also occur and include supraventricular dysrhythmias and prolongation of the PR, QT and QRS intervals.

 

Management:

1. Ensure a clear airway and adequate ventilation.

2. Multiple dose oral activated charcoal should be given to adults and children who have ingested more than 20 mg/kg body weight.

3. Observe for at least 6 hours after ingestion if a non-sustained release preparation has been taken. If CNS features have not developed by this time they are unlikely to do so. If a sustained release preparation has been taken observe for at least 12 hours.

4. Carry out arterial blood gas analysis if the patient is unconscious.

5. Correct hypoxia.

6. Correct hypotension by raising the foot of the bed or in severe cases by expanding the intravascular volume.

7. Resist the temptation to treat dysrhythmias unless they are causing peripheral circulatory failure.

8. Other measures as indicated by the patient's clinical condition.