Design and optimization of a stomach-specific drug delivery system of repaglinide: Application of simplex lattice design

Abstract

The current study involves the development of oral bioadhesive hydrophilic matrices of repaglinide and the optimization of their in vitro drug release and ex vivo bioadhesion. A simplex lattice design was employed to systematically optimize the drug delivery containing two polymers and a filler. The proportions of polyethylene oxide (PEO), microcrystalline cellulose (MCC) and lactose were varied to be fitted in simplex lattice design. Mucoadhesion (M), drug release at 2 h (Q2) and drug release at 8 h (Q8) were taken as responses. Response surface plots were drawn and the optimum formulation was selected by desirability function. The criteria for optimized formulation were set for mucoadhesion as maximum, Q2 as 20% and Q8 as 80%. The formulations were also checked for their swelling index and showed good swelling characteristic. In vitro drug release study was carried out using simulated gastric fluid (SGF) pH 1.2. The experimental values of M, Q2 and Q8 for check point batch were found to be 0.211N, 21.87% and 80.86% respectively. The release profile indicated anomalous (non-Fickian) transport mechanism. The optimized formulation was further checked for its compatibility with other excipients by studying FTIR and DSC studies and they indicated the absence of any significant chemical interaction within drug and excipients.