Self-dispersing self-assembling systems for controlled oral delivery of gliclazide

Abstract

Self-microemulsifying systems undergo self-dispersion to form microemulsion with subsequent self-assembly to form liquid crystalline (LC) and/or gel phases. These transitions modulate the release and absorption pattern of loaded drug. Accordingly, the primary objective was to evaluate these phases with respect to gliclazide release and absorption after oral administration. Pseudoternary phase diagrams were constructed using Peceol as oil, Gelucire 50/13 as surfactant and Transcutol as co-surfactant with Gelucire and Transcutol being used at 1:1 or 2:1, weight ratios. Microemulsion, LC and gel formulations were selected from these phase diagrams and were loaded with gliclazide. The selected systems were evaluated for gliclazide release which was conducted using continuous pH variation to mimic the gastrointestinal conditions. Optimum systems were subjected to in vivo evaluation. The in vivo study involved monitoring blood glucose level of diabetic rats after oral administration of gliclazide in aqueous suspension, microemulsion, LC and gel systems. Microemulsion liberated gliclazide rapidly and the rate of drug release was reduced in case of LC with further slowing in case of gel system. Interestingly, LC and gel systems liberated gliclazide steadily via zero order release kinetics. Microemulsion provided rapid reduction of blood glucose level but was not able to sustain this effect. LC and gel systems provided sustained effect and enhanced the bioavailability as shown from significant increase in the area under glucose reduction curve compared to both microemulsion and suspension form. The study thus introduced LC and gel phase as controlled release systems for oral delivery of gliclazide.