optimization of extended zero-order release gliclazide tablets using D-optimal mixture design.

The objective of this study was to develop and optimize the gliclazide extended-release formulations by using simultaneously combination of two hydrophilic polymers: HPMC K 15M and sodium alginate as retardant. D-Optimal mixture design was employed to evaluate the effect of HPMC (X(1)), lactose (X(2)), and sodium alginate (X(3)) concentrations on the release rate of gliclazide from the matrices. The drug release percent at 3, 6, 9 and 12 h were the target responses and were restricted to 20-30, 45-55, 70-80 and 90-100%, respectively. Response surface methodology and multiple response optimization utilizing the polynomial equation were used to search for the optimal formulation with specific release rate at different time intervals. Validation of the optimization study indicated high degree of prognostic ability of response surface methodology. The mechanism of drug release from optimized extended-release matrix tablets was followed by the zero-order release pattern. This study demonstrated that D-optimal mixture experimental design facilitated the formulation and optimization of extended release hydrophilic matrix systems of gliclazide.