The effect of food on the oral administration of 6-mercaptopurine.

The effect of food on the bioavailability of 6-mercaptopurine (6-MP) has been investigated. Seven patients were studied on two separate occasions. On the first occasion 6-MP was administered p.o. after an overnight fast and on the second, 15 min after a standard breakfast. 6-MP concentrations were determined by high-performance liquid chromatography. Variable plasma drug levels were observed between individual subjects in the fasting state. The peak levels of 6-MP were lower and took longer to be achieved following administration after a standard breakfast than after an overnight fast. In two subjects levels were undetectable (less than 20 ng/ml). In view of these observations it is suggested that 6-MP should be administered before food if maximum blood levels are to be achieved.