Concentrations and kinetics of carbamazepine in whole saliva, parotid saliva, serum ultrafiltrate, and serum.

Six healthy subjects received a 400-mg oral dose of carbamazepine (CBZ). CBZ concentrations were determined by enzyme immunoassay in whole saliva, serum, and serum ultrafiltrate over 82 hr. After 30 hr the log concentration-time plots declined linearly with similar elimination half-lifes in all three fluids. Although the mean ultrafiltrate curve was lower than the mean salivary curve, the area under the curve, volume of distribution, and total body clearance calculated from whole saliva and ultrafiltrate data were not different. The mean CBZ concentration ratios of whole saliva/total serum and ultrafiltrate/total serum of the individual subjects ranged from 19.6% to 34.7% and from 19.0% to 28.8%. Linear correlations were found between salivary CBZ concentrations and serum (r = 0.872, p < 0.001) and ultrafiltrate concentrations (r = 0.916, p < 0.001). Whole salivary and uncontaminated parotid salivary CBZ concentrations were not different and were independent of volume of fluid produced, pH of saliva, and degree of stimulation. These results indicate that whole saliva may be a suitable medium for monitoring free concentrations of CBZ and may provide a noninvasive alternative to blood.