title: Intraindividual variability of carbamazepine, phenobarbital, and phenytoin concentrations in saliva.
abstract: The intraindividual variability of salivary carbamazepine (CBZ), phenobarbital (PB), and phenytoin (PHT) concentrations was studied in six healthy male volunteers. During three consecutive 1-week phases, subjects took one of the antiepileptic drugs (AED) for 5 days. Nine saliva and nine blood samples were collected simultaneously over the last 4 days of each phase. Salivary, unbound serum, and total serum CBZ, PB, and PHT concentrations were determined by fluorescence polarization immunoassay. Individual mean saliva (Cs)/total serum (Ct), unbound serum (Cu)/Ct, and Cs/Cu concentration ratios for CBZ, PB, and PHT were similar to those reported previously. The intraindividual mean (+/- SD) coefficients of variation (%) of the Cs/Ct, Cu/Ct, and Cs/Cu ratios for CBZ were 4.8 +/- 2.2%, 4.4 +/- 1.8%, and 5.0 +/- 1.9%, respectively; for PB they were 5.1 +/- 0.8%, 3.6 +/- 0.9%, and 6.4 +/- 1.0%, respectively; and for PHT they were 7.4 +/- 3.1%, 5.5 +/- 1.2%, and 8.3 +/- 3.2%, respectively. The mean Cs/Ct and Cu/Ct ratios for CBZ and PHT were not significantly different, but they were different for PB (p = 0.01). However, the range of individual coefficients of variation of the Cs/Ct ratio for PB was 4.0-6.2%, which is acceptable for clinical monitoring. We conclude that the intraindividual variability of CBZ, PB, and PHT concentrations in saliva, based upon the saliva/serum concentration ratios of each AED, is not a factor that should dissuade clinicians from using saliva for the therapeutic monitoring of these agents.
authors.affiliation: Division of Pharmacy Practice, School of Pharmacy, University of North Carolina, Chapel Hill 27599.
authors.forename: M V
authors.initials: MV
authors.lastname: Miles
authors.forename: M B
authors.initials: MB
authors.lastname: Tennison
authors.forename: R S
authors.initials: RS
authors.lastname: Greenwood
mesh_terms: D000328:Adult; D002220:Carbamazepine / Q000032:analysis* / Q000097:blood; D016231:Fluorescence Polarization Immunoassay; D006801:Humans; D008297:Male; D010634:Phenobarbital / Q000032:analysis* / Q000097:blood; D010672:Phenytoin / Q000032:analysis* / Q000097:blood; D012463:Saliva / Q000737:chemistry*
chemical_list: D002220:Carbamazepine; D010672:Phenytoin; D010634:Phenobarbital