Pharmacokinetics of diethylcarbamazine: prediction by concentration in saliva

The concentration of diethylcarbamazine in saliva was used to determine pharmacokinetic parameters, in comparison to plasma and urine concentrations. Six healthy adult male volunteers were administered 150 mg diethylcarbamazine with 400 ml of water. At seven different time intervals, blood, urine and saliva samples were taken, and different pharmacokinetic parameters measured. The plasma-saliva concentration ratio was calculated as 1.53 whereas the observed ratio was 3.82. The half lives, times to reach peak plasma concentration, and elimination rate constants did not show any significant difference in the different samples. The plasma peak concentration and areas under the curve were significantly (p<0.05) increased from those of the saliva. At 24 h, when diethylcarbamazine was absent in urine, the plasma and saliva concentrations were almost zero. Diethylcarbamazine is secreted in saliva, and its concentration in saliva can be used to monitor drug therapy.