Effect of chronic co-administration of metformin and vitamin C on plasma glucose and lipid concentrations in normal rats.

In clinical setting, uncomplicated diabetes mellitus type 2 is managed with anti-oxidants (e.g. ascorbic acid, alpha-tocopherol, etc.) with standard oral hypoglycaemic agents, which is aimed at limiting its glucose auto-oxidation and lipid peroxidation complications. The current study is an experimental animal study aimed at investigating the effect of co-administration of metformin and ascorbic acid (Vitamin C) on plasma glucose and lipid levels in non-diabetic rats which could serve as a template for future studies in this area. The hypoglycaemic and hypolipidaemic activities of metformin, ascorbic acid, and metformin-ascorbic acid combination were studied in 4 groups consisting of 6 rats per group and weighing 120 - 155 g, by administering oral doses of 5, 10 and 15 (for co-administration) mg/kg/day of the drugs, respectively, for 30 days. The acute oral toxicity of the combination was also conducted using limit dose test of Up and Down Procedure of Acute Oral Toxicity test. Results of the study showed that metformin and metformin-ascorbic acid combination induced significant and comparable hypoglycaemia. The drug combination also lowered plasma total cholesterol, low density lipoprotein-cholesterol (LDL-c), very low density lipoprotein-cholesterol (VLDL-c) significantly but had no effect on plasma high density lipoprotein-cholesterol (HDL-c). The LD50 estimate of the drug combination was greater than 5000 mg/kg body weight/oral route. The results of this study suggest the drug combination could have hypoglycaemic and lipid-lowering effects.