Gastroretentive raft liquid delivery system as a new approach to release extension for carrier-mediated drug.

Gabapentin (GBP), an antiepileptic and anti-neuropathic agent, suffers from short half-life (5-7 h), has narrow absorption window, and is absorbed via carrier-mediated mechanism resulting in frequent dosing, poor compliance, and poor bioavailability (<60%). Moreover, GBP is a freely water-soluble drug, thus it is considered a challenging candidate to be formulated as extended release dosage form. In this study, raft forming systems were investigated as a potential drug delivery system for prolonging gastric residence time of GBP. A 2 full factorial design was adopted to study the effect of formulation variables (% gellan gum, % GMO, and % LM-pectin 101), on the percent of GBP released at different time intervals (1, 5, and 8 h) as well as the gel strength, and thus was achieved an optimized formula with zero-order release profile suitable for once-daily administration. In vivo assessment was performed in rats to evaluate gastric residence of the gel formed. In addition, the oral bioavailability of GBP relative to commercially available Neurontin immediate release oral solution was also investigated. Significant increase was observed for C, AUC, and AUC. The increase in relative bioavailability of GBP from the optimized formula was 1.7 folds.