Effect of antiorthostatic hypokinesia on acetaminophen pharmacokinetics and its distribution in saliva of healthy volunteers

Abstract

The pharmacokinetics of acetaminophen in a group of healthy volunteers has been studied after a single peroral administration at a dose of 625 mg under normal and antiorthostatic hypokinesia (head-down bed rest) conditions. A highly significant correlation has been established between the concentrations of acetaminophen in the blood plasma and saliva of volunteers and also between the pharmacokinetic parameters calculated from the dynamics of drug distribution in plasma and saliva. A tendency toward increased concentration of acetaminophen in saliva compared to blood plasma of volunteers; decreased time of attaining the maximum drug concentration, relative bioavailability, time of half-elimination, and mean retention time in the organism; and increased general clearance has been observed.