CORRELATION BETWEEN SERUM AND SALIVA DIGOXIN CONCENTRATION IN HEALTHY SUBJECTS

After oral administration of alcoholic solution of digoxin (8.3 μg/kg), serum and saliva samples were collected at 6 time intervals within 24 h from 7 healthy subjects. Drug concentrations in serum or saliva were determined by using RIA digoxin kit. The results showed that the correlation coefficient between the determinations of these 2 groups was 0.879 (P<0.001) for all values at each interval and was 0.999 (P<0.001) for the mean value of the corresponding interval. Basing on the serum and saliva drug concentration data, the main pharmacokinetic parameters (α, t¹/2α, β, t¹/2β) and the bioavailability of digoxin tablets in 3 healthy subjects were calculated and the average parameters and bioavailability of these 2 series were found to be close. The individual variations in serum digoxim concentration were more pronounced than that of saliva concentration. We, therefore, propose that the saliva levels might be more appropriate than serum levels for clinical digoxin monitoring.