Excretion of proguanil in human saliva

After a single oral administration of a 300 mg dose of proguanil to six volunteers, the presence of the drug in saliva was established by chromatographic and spectrophotometric methods. The tmax and elimination half-life of proguanil derived from salivary levels were 4.0 +/- 1.26 h and 15.1 +/- 1.8 h, respectively. These results are in agreement with values previously reported for the drug using plasma level data. The mean saliva: plasma proguanil concentration ratio was 0.41 +/- 0.17 and this was not time dependent. There was a correlation (r = 0.82) between the saliva and simultaneous plasma proguanil concentration. The results suggest that proguanil is passively secreted into saliva and that saliva levels may be useful in the determination of pharmacokinetic parameters and the therapeutic monitoring of the drug.