Hybrid drug combination: Combination of ferulic acid and metformin as anti-diabetic therapy

Background and purpose: Ferulic acid, an anti-oxidant phytochemical present in several dietary components, is known to produce wide range of pharmacological effects. It is approved for use in food industry as a preservative and in sports food. Previous reports from our lab have shown synergistic interaction of ferulic acid with metformin in cell lines and diabetic rats. The purpose of this review is to compile information about anti-diabetic activity of ferulic acid in in vitro and in vivo models with special emphasis on activity of ferulic acid when combined with metformin. The mechanism of synergistic interaction between ferulic acid and metformin is also proposed after carefully studying effects of these compounds on molecules involved in glucose metabolism. Methods: Scientific literature for the purpose of this review was collected using online search engines and databases such as ScienceDirect, Scopus, PubMed and Google scholar. Results: Ferulic acid forms resonance stabilized phenoxyl radical which scavenges free radicals and reduce oxidative stress. It improves glucose and lipid profile in diabetic rats by enhancing activities of antioxidant enzymes, superoxide dismutase and catalase in the pancreatic tissue. Combining ferulic acid with metformin improves both, in vitro glucose uptake activity and in vivo hypoglycemic activity of the latter. It is possible to reduce the dose of metformin by four folds (from 50 to 12.5 mg/kg body weight) by combining it with 10 mg of ferulic acid/kg body weight in diabetic rats. Ferulic acid improves glucose uptake through PI3-K pathway whereas metformin activates AMPK pathway to improve glucose uptake. Conclusion: The synergistic interaction of ferulic acid and metformin is due their action on parallel pathways which are involved in glucose uptake. Due to synergistic nature of their interaction, it is possible to reduce the dose of metformin (by combining with ferulic acid) required to achieve normoglycemia. Since the dose of metformin is reduced, the dose associated side effects of metformin therapy can be reduced.