Development and evaluation of controlled release of metformin hydrochloride for improving the oral bioavailability based on a novel enteric osmotic pump capsule

This paper demonstrated that a novel enteric osmotic pump capsule (EOPC) could effectively deliver metformin hydrochloride (MH) into the small intestine and keep releasing in a sustained manner consistently. The MH EOPC was composed of enteric semipermeable capsule shell and the core prescription fillers. Using a single factor tests, formulation and process factors were investigated and optimized based on the in vitro drug dissolution results. The optimized results were MH (250 mg), fructose (60 mg), mannitol (30 mg), polyethylene oxide-N60K (9 mg), ludipress® (49.5 mg), magnesium stearate (1.5 mg), and an orifice diameter of 0.8 mm. And, in vitro release studies showed sustained and stable drug release from the optimal MH EOPC, which was in line with the zero-order model. A higher bioavailability of MH was achieved from EOPC in comparison with commercial enteric capsules and sustained release tablets. Finally, using the technology of multislice computed tomography, as a visual means, further confirmed that EOPC achieved MH release specifically in the small intestine. In summary, the current study showed that the MH EOPC could potentially reduce MH adverse reactions and improve patient compliance which serves as an additional option for the treatment of type 2 diabetes.