Formulation development and in vitro – in vivo pharmacokinetic studies of gliclazide colon targeted matrix tablet
The colonic drug delivery system (CDDS) of Gliclazide was formulated and in vitro and in vivo pharmacokinetics studies were conducted. The colonic delivery system consists of SR matrix tablets containing Gliclazide were developed by dissimilar grade of HPMC combinations with enteric coating polymers like EudrajitL100 and S100 as coating materials, as an outlet layer, insoluble and impermeable at acidic pH but easily soluble at a pH value higher than 5.5 (EudrajitL100 and S100 ). In vitro results showed the colonic drug delivery system is capable of avoiding drug release in acidic medium for 2 h but the gliclazide drug release in phosphate buffer, pH 6.8, after 3 hrs stage of time and release was up to 24 hrs. The dissolution mechanism of drug release was more definite by Higuchi plots that showed good quality linearity (R2 values between 0.90 and 0.93), with slope > 0.5, representing that drug release mechanism from the formulations were non-fickian diffusion mechanism. Pharmacokinetic parameters like Cmax, Vd, Ke, t1/2, Cl, AUC0-∞ and MRT were designed for selected (GLZ6) formulations. Furthermore, the relative bioavailability (RB) was also found to be high, and therefore it indicates that gliclazide released extra amounts from the tablet formulation and absorbed for blood circulation with a satisfactory plasma concentration. X‑ray pictures exhibit that the selected formulation GLZ 6 could be targeted particularly to the colon, without any early drug release in the stomach and small intestine. Therefore, from this study, it had been concluded that Gliclazide matrix tablets might persuade be additional efficient in the management of diabetic patients through CDDS.
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