Comparative evaluation of gliclazide controlled release tablets using two different hydrophilic matrix systems in rabbits

Abstract

Gliclazide controlled release tablets using two different hydrophilic matrix systems were developed and evaluated in rabbits. Formulation of 30 mg gliclazide controlled release tablets was developed using hydroxypropyl methylcellulose (HPMC) or xanthan gum (XG) as matrix forming agent. Release rate of gliclazide from the matrix was characterized in comparison with a commercial product (Diamicron®MR) by varying the quantity of HPMC and XG in the range from 20 to 60% and 5 to 9%, respectively. It was found that the formulated matrices that exhibited the similar release profiles to the commercial product were those containing 20% HPMC (similarity factor, f₂ = 51.11, difference factor, f₁ = 9.81) and 7% XG (similarity factor, f₂ = 59.53, difference factor, f₁ = 8.32). Diluent in formulations and pH of release medium affected the release of gliclazide from the matrices of these two hydrophilic polymers. Bioavailability of the two selected formulations and Diamicron®MR were performed using white New Zealand rabbits. Each rabbit received a single dose of each gliclazide formulation in randomized crossover design. Blood samples were collected at predetermined time intervals post dose and determined for gliclazide concentrations by HPLC. The pharmacokinetic parameters, C[subscript max], t[script max] and AUC, obtained from 20% HPMC and 7% XG formulations were statistically significant different (p < 0.05). Furthermore, it was found that 20% HPMC and 7% XG formulation were comparable to the commercial product because all pharmacokinetic parameters obtained from this formulation were not statistically significant different (p > 0.05).