Adults

Initial: 200 mg orally twice daily. May increase by 200 mg/day every week until optimal response, usually 800-1200 mg/day in divided doses. Max: 1600-2400 mg/day.

Elderly

Start with lower doses (e.g., 100 mg twice daily) and titrate slowly due to increased sensitivity and potential for adverse effects.

Renal_impairment

No specific dose adjustment for mild to moderate impairment; use with caution in severe renal impairment, monitor plasma levels.

Onset

Antiepileptic effects may take several days to weeks to achieve full therapeutic benefit due to the need for dose titration.

Excretion

Mainly excreted in urine (72%) as metabolites, with a smaller amount (28%) excreted in feces.

Half life

Initial half-life is about 25-65 hours; however, autoinduction of metabolism reduces it to 12-17 hours with chronic administration.

Absorption

Slow and variable absorption from the CR tablet, providing sustained plasma concentrations. Peak plasma concentrations are reached in 4-8 hours for conventional tablets, and typically 4-12 hours for CR formulations.

Metabolism

Extensively metabolized in the liver, primarily by CYP3A4, to an active metabolite, carbamazepine-10,11-epoxide, which also contributes to its pharmacological activity.

Warfarin

Reduced anticoagulant effect due to increased metabolism of warfarin.

MAO inhibitors

Contraindicated due to risk of hypertensive crisis and severe adverse effects.

Oral contraceptives

Reduced efficacy of contraceptives due to enzyme induction by carbamazepine.

Other antiepileptics (e.g., phenytoin, valproate)

Complex interactions, often leading to altered plasma levels of both drugs.