Carbamazepine as an anticonvulsant

In preparation for a major double-blind, crossover study comparing carbamazepine with diphenylhydantoin (DPH), a pilot study was carried out in 12 patients who had a minimum of four focal or major seizures per month. The dose equivalency between carbamazepine and DPH was found to be 3 to 1, and the study demonstrated an effective method for crossover from one agent to the other. It was determined that the half-life of carbamazepine is in the 12-hour range, so that twice-daily doses are effective. At high dosages, acute toxicity could be avoided by giving thrice-daily doses. In 7 of the 12 patients in the pilot study, carbamazepine was the preferable drug. It appears to be an effective independent anticonvulsant of the same order of magnitude as DPH.