- Used as an anti-epileptic drug, in the management of trigeminal neuralgia and as a mood stabiliser in psychiatric disease
- Similar mechanism of action to phenytoin i.e. binding and stabilising inactive Na+ channels, reducing generation of action potentials
- Almost 100% oral bioavailability
- 75% protein bound
- VD 1L/kg
- Extensive hepatic metabolism to the active metabolite carbamazepine 10,11-epoxide (retains 30% anticonvulsant activity)
- Induces its own metabolism
- Long half-life: 25 - 65hrs
- Excretion almost exclusively renal as unconjugated metabolites
- Is a powerful CYP450 enzyme inducer
- Levels of carbamazepine may be increased by erythromycin
- Increases risk of SLE in woman by 90%
- Mild neurotoxic effects are common and limit its use
- Other effects include headache, diplopia, ataxia, vomiting and drowsiness
- With chronic use can cause resistance to aminosteroid NMBA
- Anti-diuretic effect leading to SIADH/water retention
- Dose-dependent teratogenicity affecting 1 in 300 - 2,000 live births
- Foetal Hydantoin Syndrome
- Facial abnormalities and microcephaly
- IUGR and mental retardation