Time dependent changes in the pharmacokinetics of aspirin.

In an experiment carried out on six volunteers, measurement of total serum salicylate concentration was used to describe aspirin kinetics after a single 1500 mg oral dose. The availability of the drug was significantly better when it was administered at 6(00) than at 18(00) or 22(00). Also a significant time-dependence was found between the morning and evening values of both the serum half-life time of salicylate and kel. The possible relation between these results and the appearance of undesirable side effects in patients should be examined.