Voltage-gated sodium-channel blocker — first-line for partial epilepsy + trigeminal neuralgia. Potent CYP3A4 + CYP2C9 + UGT auto-inducer (own ke rises 2-3× by week 4). HLA-B*1502 + Asian ancestry → SJS/TEN risk. Major DDI source.
Half-Life (t½)
PO: 33h
Dosing Guidelines
PO: Typical 400 mg (Range: 200–1200 mg)
Target Organ Systems
digestive
immune-hematologic
Interactions
Warfarin (major): CYP2C9 induction. Documented in case reports (PMID:24612117 et al.) showing warfarin dose increases of ~3× to maintain INR. No primary HV abstract reports verbatim AUC fold-change → kinetics block deferred until full-text Ki/induction_factor available.
Cyclosporine (major): CYP3A4 induction. Cooney 1995 (PMID:7667170): carbamazepine reduced cyclosporine dose-normalized average steady-state concentration to <50% of control in pediatric renal transplant patients. Increase cyclosporine dose ~2× and monitor trough.
Simvastatin (major): CYP3A4 induction. Ucar 2004 (PMID:14691614) verbatim: "Carbamazepine decreased the mean total area under the serum concentration-time curve of simvastatin and simvastatin acid by 75% (P<0.001) and 82% (P<0.001), respectively". 12 healthy volunteers, randomized 2-phase crossover, CBZ 600 mg/d × 14d (200 mg/d first 2d) + single 80 mg PO simvastatin. AUC ↓75% → induction_factor 1/0.25 = 4.0. t½ simvastatin acid 5.9 → 3.7 h.
Midazolam (major): CYP3A4 induction. Backman 1996 (PMID:8598183) verbatim: "the area under the plasma concentration-time curve (AUC) of midazolam (mean +/- SEM) was only 5.7% (0.60 +/- 0.16 vs. 10.5 +/- 0.6 microgram x min/ml) ... of its value in control subjects (p < 0.001)". Caveat: 6 epilepsy patients on CBZ OR phenytoin pooled vs 7 controls — combined-cohort effect; authoring under CBZ as the dominant CYP3A4 inducer. AUC 5.7% of control → induction_factor 17.5.
Hormonal contraceptives (warn): CYP3A4 induction (ethinylestradiol). Crawford 1990 (PMID:2126946) verbatim: "Carbamazepine reduced the AUC for EE2 from 1163 +/- 466 to 672 +/- 211 pg ml-1 h (P less than 0.05) and for Ng from 22.9 +/- 9.4 to 13.8 +/- 5.8 ng ml-1 h (P less than 0.05)". n=4 women on CBZ 8-12 wk, single-dose 50 µg EE2 + 250 µg levonorgestrel. EE2 AUC 672/1163 = 0.578 → induction_factor 1.73. Contraceptive failure risk well-documented.