The metabolism of phenobarbitone, phenytoin and antipyrine in Black patients.

The half-lives of phenytoin, phenobarbitone and antipyrine were studied in adult Black patients to attempt to ascertain the cause of low phenytoin concentrations previously found in Black epileptics. The following half-life values were observed: antipyrine 5,7 +/- 1,9 hours, phenytoin 15,9 +/- 7,9 hours, phenobarbitone 63,0 +/- 18,2 hours, and phenytoin after 1 month of phenobarbitone therapy 31,5 +/- 11,9 hours. No explanation was obtained for the low phenytoin levels previously observed.