Design and Optimization of Controlled Release Felbamate Tablets by D-optimal Mixture Design: In vitro-in vivo Evaluation

Felbamate, an antiepileptic drug is administered multiple times a day to obtain proper restorative action against seizures in childhood onset epilepsy (Lennox-Gastaut syndrome), which usually result in poor therapeutic efficacy because of fluctuating plasma levels and low patient compliance. Hence, controlled release hydroxypropyl methylcellulose matrix tablets of felbamate were formulated to overcome these drawbacks. The results of pre-formulation studies such as differential scanning calorimetry and Fourier-transform infrared spectroscopy showed compatibility of drug with the selected excipients. The formulation variables were optimized using D-optimal design, which can elucidate the effect of all variables simultaneously during formulation optimization. In vitro drug release at the end of 2, 8 and 20 h were taken as the response parameters for the optimization study by D-optimal design. The results enabled selection of the formulation with the desired drug release pattern approaching to zero order. The optimized batch was subjected to in vivo pharmacokinetic studies in rabbits, which showed extended release of drug up to 24 h. Thus, the felbamate controlled release tablets optimized by D-optimal design have potential to reduce the dose and dosing frequency, improve therapy and patient compliance.