oxcarbazepine TRILEPTAL
Class: AED/Mood StabilizerFDA Indications: Partial Seizures
Off-Label Use: Neuropathic Pain, Bipolar Disorder, Restless Leg Syndrome
Prescribing
Forms: 150, 300, 600mg tablet; 300 mg/5 mL po solnDose Range: 600-2400 mg/day
Starting: 300 mg bid; usual daily dose is 1200 mg/day in 2 divided doses; dosage ↑'s are made Q3 days in increments of 150 mg or 300 mg depending on weight and tolerability
Stopping: Taper. Abrupt discontinuation can elicit seizures and increase the risk of relapse in bipolar patients
Monitoring: Serum Na+ for 1st 3 mos b/c of possibility of hyponatremia
Precautions
Serious Side Effects: Hyponatremia (2.5%)Side Effects: dizziness (20-49%), drowsiness (12-36%), headache, ataxia, fatigue, tremor, vomiting, nausea, diplopia, visual changes, nystagmus
Pharmacodynamics
1° MOA: Binds to a site located within the open channel conformation of the VSSC α subunit, which decreases repetitive firing and spread of electrical activityPharmacokinetics
t½: 7-20° TMAX: 4.5°Substrate of: AKR (oxcarbazepine→MHD), UGT (MHD→inactive metabolites→renal elimination)
Inhibits: 2C19; Induces: 3A4, UGT1A4
Active Metabolites: MHD
DDIs
- - ↑'s levels of phenytoin
- - ↓'s levels of lamotrigine & topiramate
- - ↓'s levels of ethinylestradiol & levonorgestrel
Misc
- - oxcarbazepine is a prodrug that is virtually entirely converted into MHD (by cytosolic AKR), which is responsible for the pharmacological effect of the drug
- - unlike carbamazepine, MHD does not cause autoinduction of its own metabolism
- - t½ of parent drug is 1-5°; t½ of MHD is 7-20°
- - low potential for drug interactions
- - compared to carbamazepine, less sedating, has less bone-marrow toxicity, and has fewer CYP3A4 interactions
Special Populations
Category C—Limited Human Data–Animal Data Suggest Risk: is embryo and fetal toxic and teratogenic in some animal species
Limited Human Data–Probably Compatible
No adjustments required
No dosage adjustment required in mild-moderate impairment, but should be initiated at ½ the usual starting dose in severe impairment (CrCl <30 mg/min)
No dose adjustment is needed for hepatically impaired subjects
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