Relationship between carbamazepine concentrations in serum and saliva of Thai epileptic patients

Abstract

This study aims to examine and verify the correlation between serum and saliva carbamazepine concentrations in Thai epileptic patients. The subjects were patients aged 15-60 years old who were under treatment with carbamazepine. Carbamazepine concentrations in the blood and saliva samples were measured by a fluorescence polarization immunoassay. Blood and saliva samples of 12 patients receiving carbamazepine monotherapy were collected before and at 1, 3, 5 and 8 h after carbamazepine administration to construct a regression equation of the relationship between serum and saliva carbamazepine concentrations. Based on the results obtained, a significant linear correlation between the serum (y) and saliva (x) carbamazepine concentrations (r = 0.929, p<0.001) with a regression equation of y = 2.402x + 2.397 was demonstrated and being further verified by blood and saliva samples of 30 patients collected before and at 3 h after carbamazepine administration. By using the constructed regression equation, saliva carbamazepine concentrations of these 30 patients were used to estimate their respective calculated serum carbamazepine concentrations. As expected, no significant difference between the calculated and the measured carbamazepine concentrations in serum collected before carbamazepine administration in these patients. The results of the present study support the use of saliva as an alternative to serum for monitoring carbamazepine therapy.