Poster Presenter

Design, characterization and in vitro dissolution testing of oral sustained-release Metformin hydrochloride using semisolid matrix systems
Doua Al-Saad, Marwa Alaamri, Nahla Jabr and Husam M. Younes
Qatar

Purpose: To design, formulate and test the dissolution of new oral dosage forms of Metformin hydrochloride (MH) in semisolid polymeric matrices having sustained-release properties suitable for once-a-day or twice-a-day administration that would increase MH bioavailability and also address the shortcomings in the currently available sustained release tablets.

Methods: MH micronized powder was dispersed in molten polymeric matrices composed of various proportions of high molecular weight hydrophilic polymers, hydrophobic oily semisolid excipients, and muco-adhesive polymeric materials. The DSC and X-ray analysis was conducted to test crystallinity. The following formulations each of which containing 400 mg MH were filled into size zero hard gelatin capsules (HGC) and were subjected to in vitro dissolution testing using USP basket method at 50 rpm using 1000 ml distilled water as dissolution medium. MH was analyzed using UV spectrophotometric analysis. Glucophage^® 500 mg tablets were used as reference.

Formulation	Content of capsule
A	400 mg MH + 400 mg Gelucire 50/13
B	400 mg MH + 80 mg PEG400 + 60 mg PEG 6000 + 40 mg PEG 35000 + 220 mg Gelucire 50/13.
C	400 mg MH + 200 mg PEG 6000 + 200 mg Gelucire 50/13
D	400 mg MH + 100 mg PEG 35000 + 300 mg Gelucire 50/13

Results: The above tabulated formulations resulted in extended-release profiles that lasted between 6-8 hours and demonstrated bimodal release pattern which characterizes the release from mixes of triglycerides with polyethylene glycol esters of fatty acids. The incorporation of PEG 6000 or PEG 35000 (Forms C&D) resulted in an overall faster dissolution rate compared to formulation A with complete release achieved after 6 hours. On the other hand, PEG400 incorporation to formulation B resulted in a fast initial release followed by a slower release rate following the first 3 hours. Thermal and X-ray analysis of the formulations showed significant decrease in MF crystallinity.

Conclusion: Capsules formulated using semisolid matrices showed promising results in extending the release of MF. However, bioavailability studies to test the ability of Gelucire based capsules of MF to improve its bioavailability and residence time are future plans.

Acknowledgements: Doua Al-Saad and Marwa Alamiri are recipients of Undergraduate Research Experience Program (UREP) award. This project was supported by UREP/Qatar Foundation.