Overdose : מינון יתר

4.9. Overdose

In case of intoxication, the possibility of multiple poisoning, for example through the ingestion of several drugs with suicidal intent, must always be considered.

Carbamazepine intoxication usually occurs with very high doses (4 - 20 g), where the plasma level is always over 20 µg/mL. Accidental or suicidal ingestion with plasma concentrations of 38 µg/mL has been survived.

The literature contains reports of intoxication (after taking carbamazepine with suicidal intent or accidentally), some of which had fatal consequences.

Symptoms of overdose
The symptoms described under undesirable effects can be intensified on overdosing with carbamazepine:


CNS depression, dizziness, ataxia, drowsiness, stupor, coma, nausea, vomiting, delayed gastric emptying, restlessness, confusion, involuntary movements, dysarthria, mydriasis, nystagmus, flushing, urinary retention, cyanosis, respiratory depression, opisthotonus, abnormal reflexes (weakened or enhanced).

The following additional symptoms may occur: tremor, excitement, tonic-clonic convulsions, respiratory and cardiovascular disturbances with, for the most part, hypotonic blood pressure (but sometimes hypertension), tachycardia and AV block, impaired consciousness up to respiratory and cardiac arrest.

EEG dysrhythmias and ECG changes (arrhythmias, conduction disorders) can arise.
Modified laboratory parameters have been measured in isolated cases: leucocytosis, leucopenia, neutropenia, glycosuria, acetonuria.

There have been a few cases in which rhabdomyolysis was reported in association with carbamazepine toxicity.

Management of intoxication
There is to date no specific antidote to acute intoxication with carbamazepine.

Therefore cases of overdose should be treated with symptomatic measures: hospitalisation, check of carbamazepine plasma level to confirm the carbamazepine-intoxication and to determine the degree of overdose, removal of the drug as soon as possible (through induced vomiting and/or gastric lavage) and reduction of absorption by administration of activated charcoal or a laxative. Delayed gastric emptying may result in delayed absorption, leading to relapse during recovery from intoxication.

Vital functions must be safeguarded under clinical conditions: plasma concentration and cardiac function should be monitored, correction of electrolyte balance may be necessary.

Suitable anticonvulsants should be given if seizures occur. The use of barbiturates is not recommended in the literature due to the risk of inducing respiratory depression, especially in children.

A haemoperfusion with activated charcoal was recommended. Haemodialysis is an effective option for treating a carbamazepine overdose.