Pharmacokinetic comparison of tablet and suspension dosage forms of carbamazepine

The bioavailability of two preparations of carbamazepine--the tablet and a new syrup-was studied in 9 adult male volunteers by measuring saliva and serum levels. Peak time was significantly earlier and peak level significantly higher in serum for syrup as compared to tablet. Levels remained higher for syrup for 12 hr. Saliva was contaminated for up to 2 hr by syrup ingestion, possibly for a half hour by the tablet. Beyond that, saliva/serum ratios remained stable. Saliva level variation was too large for pharmacokinetic studies but acceptable for clinical purposes if sampling was long enough after the last dose.