Adults

Epilepsy: Initially 200 mg CR twice daily, increasing weekly by 200 mg CR up to 800-1200 mg CR/day. Trigeminal Neuralgia: Initially 100 mg CR twice daily, increasing by 100 mg CR every 12 hours until pain relief, typically 400-800 mg CR/day. Bipolar Disorder: Initially 200 mg CR twice daily, gradually increasing to 400-1600 mg CR/day.

Elderly

Lower starting doses and slower titration may be necessary due to increased sensitivity to side effects.

Renal_impairment

Use with caution. Dosage adjustments may be required, although carbamazepine is not significantly cleared by the kidneys, metabolites may accumulate.

Onset

Gradual, due to extended-release.

Excretion

Primarily renal (72%), some fecal (28%).

Half life

Initial: 25-65 hours; Chronic: 12-17 hours (due to autoinduction).

Absorption

Slow and variable, extended-release formulation provides sustained plasma concentrations.

Metabolism

Extensive hepatic metabolism primarily via CYP3A4 to an active metabolite, carbamazepine-10,11-epoxide.

0

CYP3A4 inducers (e.g., phenobarbital, phenytoin): May decrease carbamazepine levels.

1

CYP3A4 inhibitors (e.g., erythromycin, diltiazem): May increase carbamazepine levels.

2

Oral contraceptives: Carbamazepine may reduce efficacy of oral contraceptives.

3

Warfarin: May decrease anticoagulant effect.

4

Other antiepileptics (e.g., valproate, lamotrigine): Bidirectional interactions, potential for increased toxicity.