Evaluation of co-polymer based granulated metformin hydrochloride for encapsulation in hard gelatin capsule: An in vitro study

Abstract

Background and aim: This study explores copolymer combination with the sole aim of improving the release profile of encapsulated metformin hydrochloride.
Methods: Varied ratios (1:1, 2:1, and 1:2) of hydroxypropyl methyl cellulose (HPMC) and guargum were used as copolymer matrix to encapsulate granulated metformin. Thereafter the final granules were manually filled in a hard gelatine capsule size 00. Evaluation such  as thermal behaviour using differential scanning calorimeter (DSC), drug entrapment efficacy (DEE) using dialysis membrane, and flow properties using cone-funnel methods were carried out.
Results: The DSC shows a transient, but no obvious peak due to heat of absorption, and there was no obvious peak of the polymers  noted. This is a possible indication of no incompatibility. The DEE result showed good granule entrapment of > 97.46 %. Micromeritics  analysis showed Carrs’ indices 8.55 – 23.08 %, Hausner ratio 1.094 – 1.300 and angle of repose 27.54 – 41.54o , all these are indication of  good flow properties. The capsules showed passable disintegration of < 9.10 min, with correlation-coefficient in the range of 0.91-0.97.  The mechanism of release was found to be Korsemeyer-Peppas with n-value release exponent of > 1.0 for super case II diffusion. Conclusion: The drug release properties of encapsulated metformin in HPMC and guar gum was found to be highest in the formulation  consisting of 2.0 % HPMC and 4.0 % guar gum.