A comparative bioavailability study of carbamazepine tablets and a chewable tablet formulation

Area of Science:

• Pharmacology
• Drug Formulation
• Clinical Pharmacokinetics

Background:

• Drug product formulation impacts therapeutic outcomes by altering drug bioavailability and pharmacokinetics.
• Carbamazepine (CBZ) is a widely used antiepileptic and mood-stabilizing drug.

Purpose of the Study:

• To compare the relative bioavailability and pharmacokinetics of carbamazepine (CBZ) tablets and a chewable tablet formulation.
• To assess the interchangeability of different CBZ dosage forms.

Main Methods:

• A randomized, crossover study in 10 healthy subjects.
• Administration of a 200-mg dose of CBZ in two different formulations.
• Serial blood sampling over 48 hours post-dose.
• Plasma CBZ concentrations measured by fluorescence polarization immunoassay.

Main Results:

• No statistically significant differences in key pharmacokinetic parameters (Ke, Tmax, AUC) between the two formulations.
• A higher Cmax was observed with the chewable formulation, but deemed not clinically relevant.
• Relative bioavailability of the chewable formulation compared to the tablet was 0.92.
• Significant intra- and intersubject variability in absorption was noted for both formulations.

Conclusions:

• Carbamazepine (CBZ) tablets and chewable formulations can be considered interchangeable based on pharmacokinetic profiles.
• Considerable variability in drug absorption highlights the importance of individual patient monitoring.
• Mild, transient side effects were reported with the chewable formulation in a small number of subjects.