Pharmacodynamic Interactions between Puerarin and Metformin in Type-2 Diabetic Rats

Herb–drug interactions are vital in effectively managing type-2-diabetes complications. Puerarin is a natural isoflavonoid in the Pueraria genus, and its pharmacological activities, including antidiabetic activity, are well established. The similar modes of action of puerarin and metformin in diabetic models suggest their positive pharmacodynamic interactions. This study investigated this in streptozotocin/nicotinamide-induced type-2 diabetic rats. Puerarin at doses of 80 mg/kg, 120 mg/kg and 160 mg/kg improved the activity of metformin in reversing hyperglycaemia, dysregulated lipid profiles, dysfunction of the liver, kidney, and pancreas, and inflammation. The treatment with either puerarin (high dose, 160 mg/kg intraperitoneally) or metformin (100 mg/kg intraperitoneally) did not bring the dysregulated biomarkers to normal levels in 4 weeks. By contrast, the combination of puerarin (160 mg/kg) and metformin (100 mg/kg) did. This study is the first to report scientific evidence for the positive pharmacodynamic interactions between puerarin and metformin.