Use of Saliva in TherapeuticDrugMonitoring

We measured the concentrations of phenobarbital, phenytoin, primidone, ethosuximide, antipyrine, and caf-feine in paired samples of saliva and plasma by gas chromatograph-mass spectrometer-computer (GC/ MS/COM) and enzyme immunoassay. Mixed saliva was collected for the antipyrine and caffeine studies, parotid saliva for the phenobarbital, pi-imidone, ethosuximide and phenytoin studies. The saliva/plasma (SIP) ratios (by weight) obtained by GC/MSICOM were: phenobarbital, 0.31-0.37; phenytoin, 0.11; ethosuximide, 1.04; antipyrine, 0.83-0.95; caffeine, 0.55. The S/P ratio obtained by en-zyme immunoassay were: phenobarbital, 0.32; phenytoin, 0.12; primidone, 0.85. The concentrations of phenytoin, primidone, ethosuximide and antipyrine in saliva corre-spond to the free fraction of the drug in plasma. When w