Abstract

The efficacy and tolerability of oxcarbazepine, a keto derivative of carbamazepine, has been assessed in six patients (two males, four females; mean age 61 years, range 42-77), with trigeminal neuralgia refractory to carbamazepine therapy, over a period of 6 months. An excellent therapeutic response to oxcarbazepine was seen in all patients with pain control correlating well with serum drug concentrations of oxcarbazepine and its primary active metabolite 10-OH-carbazepine. Onset of the effect was observed within 24 hours in all cases. An overall serum therapeutic concentration range, in the six patients, of 50-110 mumol/l of 10-OH-carbazepine corresponding to a daily effective dose range of 1200-2400 mg (14.6-35.6 mg/kg body weight) oxcarbazepine, was observed. There was a significant correlation between oxcarbazepine dose and serum oxcarbazepine (r = 0.695, p less than 0.05) and 10-OH-carbazepine (r = 0.957, p less than 0.001) concentrations. Oxcarbazepine was well tolerated and no significant side effects were identified, though a mild hyponatraemia was observed during high doses (greater than 28 and greater than 35 mg/kg/day) in two patients. It is concluded that oxcarbazepine has potent antineuralgic properties in the absence of significant side effects and therefore may be useful in the management of intractable trigeminal neuralgia.