A study on the interaction between metformin and constituents of a commercial herbal product

Purpose: To investigate the interactions between metformin and Yoyo Bitters® including some of its constituents in the management of diabetes mellitus.
Method: Using the generic form of metformin (Glucophage®) tablets, tests such as disintegration time, dissolution profile, Fourier transform infrared (FTIR) spectroscopy and in vivo hypoglycaemia tests using Wistar albino rat were performed for metformin to investigate its behaviour in the presence and absence of Yoyo Bitters and some plant extracts used in its formulation.
Results: Metformin tablets used met BP specification in terms of pharmaceutical properties. There was no significant change in the disintegration properties of the metformin tablets in the presence of Yoyo Bitters (p > 0.05) while a significant change occurred in the dissolution profile (p < 0.05). The FTIR spectra showed some level of interactions due to disappearance of some spectral peaks. In vivo result showed a significant reduction (p < 0.05) in the duration of action of metformin.
Conclusion: Concomitant administration of metformin and Yoyo Bitters showed interaction that appeared antagonistic to the hypoglycaemic effect of metformin both in vitro and in rat models