Carbamazepine (Equetro)

Anticonvulsant (glutamate voltage-gated sodium and calcium channel blocker)

Dosing

Use ER, start 100mg 1 po qhs x4days, 2 po qhs x4days, 1 po qam 2 po qhs x4days, 2 po bid x7days. Can shift more to night. For mania, average dose 674mg, average serum level 6-7 but therapeutic range is not clear so dose by response.

Carbamazepine lowers its own levels after 3-6 weeks (auto-induction), so check levels after titration and again 1 month later (check 5 days after dose stabilizes). Carbatrol is same as Equetro (both are ER), but only Carbatrol is generic. There is also an XR but it does not yield as steady levels.

INTERACTIONS: induces CYP1A2, 2C9, 2C19, 2A6, and 2B6, as well as the glucuronidation system that lamotrigine is metabolized through. Carbamazepine lowers all atypical antipsychotics except asenapine. Avoid with quetiapine (it lowers levels 80% and raises an antidepressant metabolite). You need to double their lamotrigine dose 5-7 days after starting carbamazepine. Lowers many other medications, but definitely warn of lowering BIRTH CONTROL. Other drugs raise carbamazepine levels (grapefruit, CYP3A4 inhibitors).

Management

Like Depakote, carbamazepine works better in rapid cycling, mixed states, and sub abuse comorbidity. well-tolerated overall among mood stabilizers.

TOLERABILITY: Double vision, dizziness, fatigue – all dose dependent.

RISKS: Will lower oral contraceptive (birth control) efficacy. Severe allergic rash like lamotrigine (if Asian, must check HLA-B*1502 gene before starting and do not use if positive). Neutropenia (2-6 per million for each year on it). Hyponatremia (more common on oxcarbazepine though).

EMR Text