In vitro and in vivo evaluation of alginate and alginate-chitosan beads containing metformin hydrochloride

Purpose: To prepare metformin HCl-loaded alginate (AL) and alginate-chitosan (AL-CS) beads for oral application and to evaluate their in vitro characteristics and in vivo activities.
Methods: AL and AL-CS beads were prepared using ionotropic gelation. The beads were evaluated for particle size, surface morphology, drug encapsulation efficiency (EE) and in vitro drug release. The anti-diabetic effects of the beads were evaluated in diabetic Sprague Dawley rats.
Results: The mean particle sizes of AL and AL-CS beads in wet state ranged from 1714 ± 140 to 1850 ± 103 μm. The EE % of AL and AL-CS beads were 33.58 ± 1.56 and 24.11 ± 1.72, respectively, with sustained in vitro drug release of about 93 to 96 % within 8 days in phosphate buffer (PB). Optimized metformin HCl-loaded AL and AL-CS beads showed significant hypoglycaemic effects in diabetic rats over a prolonged period (about 12 h) after oral administration compared to the pure drug (p < 0.05).
Conclusion: Metformin HCl-loaded AL and AL-CS beads for oral application may be useful in prolonging the hypoglycaemic effect of metformin. This is capable of increasing patients’ compliance to the medication.