Formulation, Pharmacokinetics evaluation, and IVIVC Assessment of Gliclazide Multiparticulates in Rat Model

In vitro and in vivo studies of gliclazide (GLZ)-loaded freeze-dried alginate-gelatin (AL-GL) beads were carried out, aiming to modify its oral bioavailability. Crosslinked freeze-dried GLZ AL-GL beads (particle size: 1.5- and 3.0-mm) were prepared. In vitro evaluation of GLZ AL-GL beads included SEM, DSC, FT-IR, and release rate study in gradient media. In vivo study was single-dose (4 mg/kg), randomized, parallel-group design, two-treatment (T: test GLZ AL-GL beads and R: reference product Diamicron® 30-mg MR tablet) conducted in 96 healthy rats. Each group was subdivided into 2 sub-groups (G1 and G2) having different blood sampling schemes for up to 72 h. Assessment of level A in-vitro-in-vivo correlation (IVIVC) model was carried out. AL-GL beads successfully increased GLZ release rate compared to R. GLZ percent released (Q_4h) was 109.34, 86.85, and 43.43% for 1.5-mm and 3.0-mm beads and R, respectively. DSC analysis confirmed the interaction of AL-GL via crosslinking. No chemical interaction of GLZ has occurred as proved by FT-IR. Relative bioavailability (T/R) for AUC_0-∞ was 132.45% for G1 and 146.16% for G2. No significant differences between T and R in the primary pharmacokinetic parameters were determined. T_max values were found to be earlier in the case of G1 than those of G2. A secondary absorption peak of GLZ was clearly detected in the case of R while its sharpness was minimized in T. High IVIVC was established, and hence, the proposed in vitro release model perfectly correlated with the in vivo study. The current study design might be a platform to enable panoramic view for GLZ variability in vivo.