The application of half-life in clinical decision making: Comparison of the pharmacokinetics of extended-release topiramate (USL255) and immediate-release topiramate.

Objective: For extended-release drugs with multi-compartment kinetics, such as topiramate, effective half-life (t) may be a more clinically relevant parameter than elimination half-life (t). Using topiramate as a real-life example, the objective was to compare these half-life values for immediate- and extended-release topiramate (TPM-IR and USL255, respectively) to understand how drug pharmacokinetics may impact drug dosing recommendations.

Methods: The t and t for USL255 and TPM-IR were compared using data from a phase I study (N=36) of 200mg USL255 administered once daily (QD) or TPM-IR twice daily (BID); effect of sampling duration on t was investigated.