Trigeminal neuralgia: its treatment with two new carbamazepine analogues.

The dihydroketo and dihydromonohydroxy analogues of carbamazepine (GP 47680 and GP 47779) were tested against carbamazepine for efficacy and tolerability in 13 patients (6 male and 7 female, mean age 69 years) and 11 patients (5 male and 6 female, mean age 64 years), respectively, all of whom were suffering from trigeminal neuralgia. Both derivatives brought about freedom from symptoms or a marked reduction in the pain in all patients. Onset of effect was observed within 48 h in most cases. For both analogues the effective dose was between 10 and 20 mg/kg body weight in most patients. There was a linear relationship, with a correlation coefficient of 0.83 (n = 36; p less than 0.001), between the doses and the serum level. Doses almost twice as high as those of carbamazepine are needed in order to achieve freedom from symptoms with the carbamazepine analogues. Since unwanted effects, in the form of dizziness and ataxia, occur much less frequently than with carbamazepine, the analogues can be administered in higher doses.