Oxcarbazepine is rapidly metabolized by cytosolic liver enzymes to the pharmacologically active metabolite MHP, which is subsequently glucuronidated. Minor amounts of MHP (about 4% of the dose) are oxidized to form the inactive metabolite 10,11-dihydroxy derivative (BHP).
Oxcarbazepine is excreted as metabolites mainly by the kidneys (95%), less than 1% is excreted unchanged. Approximately 80% of the excreted metabolites are MHP, of which 49% are glucuronides and 27% are unchanged MHP. BHP is excreted unchanged (about 3%), oxcarbazepine conjugates account for 13%. About 4% of the dose is excreted in the feces.