Clinical pharmacology
Carbamazepine is metabolized and eliminated by the liver. It is metabolized by the hepatic P450 system (in particular, the 3A4 isoenzyme). Carbamazepine is ~70-80% protein-bound.
Carbamazepine induces its own metabolism (autoinduction) within the first month of treatment and also accelerates the metabolism of other hepatically metabolized drugs (see Interactions of Tegretol-XR with other drugs). The half-life in chronic therapy (that is, after autoinduction is complete) is 10-20 hours in young adults but is shorter in children and longer in the elderly.
The main metabolite of carbamazepine is carbamazepine-10,11-epoxide. This metabolite is active and also is associated with neurotoxicity.
