title: Lack of pharmacokinetic interaction between oxcarbazepine and lamotrigine.
abstract: Epilepsy and bipolar disorder are commonly treated by combination drug therapy, such as lamotrigine and oxcarbazepine. To ensure the safety of this combination, information on pharmacokinetics and tolerability must be available. The objective of study was to evaluate the pharmacokinetics and tolerability of coadministered lamotrigine and oxcarbazepine in healthy subjects. This randomized, single-blind, parallel-group study comprised three cohorts: lamotrigine (200 mg daily) plus oxcarbazepine (600 mg twice daily), lamotrigine (200 mg daily) plus placebo, and oxcarbazepine (600 mg twice daily) plus placebo. Serial blood samples were collected at steady state to determine serum concentrations of lamotrigine and plasma concentrations of oxcarbazepine and its active metabolite 10-monohydroxy metabolite (MHD). Pharmacokinetic parameters were determined by noncompartmental methods. Tolerability was monitored through adverse event reports, clinical laboratory results, vital signs, and electrocardiograms. A total of 47 male volunteers received study drugs. At steady state, lamotrigine AUC((0-24)) and C(max) were not significantly affected by oxcarbazepine co-therapy, nor were MHD AUC((0-12)) and C(max) significantly affected by lamotrigine co-therapy. The most common adverse events, headache, dizziness, nausea, and somnolence, occurred more frequently during lamotrigine and oxcarbazepine combination therapy than during the monotherapy. No significant changes in clinical laboratory parameters, vital signs, or electrocardiograms were reported. In conclusion, the combination of lamotrigine and oxcarbazepine does not require dose adjustments based on pharmacokinetic data. However, it is important to recognize that the combination therapy was associated with more frequent adverse events.
authors.affiliation: Clinical Pharmacology Unit, University of Cambridge, Addenbrookes Center for Clinical Investigation, Addenbrookes Hospital, Hills Road, Cambridge CB2 2GG, UK. Jochen_Theis@hotmail.com
authors.forename: Jochen G W
authors.initials: JG
authors.lastname: Theis
authors.forename: Jagdev
authors.initials: J
authors.lastname: Sidhu
authors.forename: Joanne
authors.initials: J
authors.lastname: Palmer
authors.forename: Sarah
authors.initials: S
authors.lastname: Job
authors.forename: Jonathan
authors.initials: J
authors.lastname: Bullman
authors.forename: John
authors.initials: J
authors.lastname: Ascher
mesh_terms: D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects / Q000493:pharmacokinetics*; D019540:Area Under Curve; D002220:Carbamazepine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D004311:Double-Blind Method; D004347:Drug Interactions; D006801:Humans; D000077213:Lamotrigine; D008297:Male; D008875:Middle Aged; D000078330:Oxcarbazepine; D013056:Spectrophotometry, Ultraviolet; D014227:Triazines / Q000009:adverse effects / Q000493:pharmacokinetics*
chemical_list: D000927:Anticonvulsants; D014227:Triazines; D002220:Carbamazepine; D000077213:Lamotrigine; D000078330:Oxcarbazepine