Enteric-coated insulin capsules: a combination with or a replacement of oral hypoglycaemic drugs

The hypoglycaemic effect of Eudragit S100 enteric-coated insulin capsules containing sodium salicylate as an absorption promoter, oral hypoglycaemic tablets sulphonylurea (e.g. doanil 5 mg) and metformin (e.g. glucophage 500 mg) was studied in hyperglycaemic beagle dogs. The effect of the combinations of insulin capsules + doanil, insulin capsules + glucophage and the combination of doanil + glucophage is also studied. The results show that the enteric-coated insulin capsules produced the same results as the glucophage tablets with respect to Cmax, AUC and relative hypoglycaemia. While, doanil tablets produced non significant lowering (P > 0.05) of Cmax and a significant less (P < 0.05) AUC compared to that produced by insulin capsules and lower (P < 0.001) RH compared to that of insulin capsules or glucophage tablets. The combination of glucophage and doanil tablets resulted in synergistic effect producing 59 +/- 9.27% reduction in plasma glucose levels by 4h and significantly higher (P < 0.001) AUC and RH compared to either of the tablets alone. The combination of insulin capsules and doanil tablets produced only 16% lowering in plasma glucose levels by 6h and significantly (P < 0.001) lower AUC and RH compared to the combination of glucophage + doanil. The combination of insulin capsules and glucophage tablets produced about 38% reduction in plasma glucose levels and significantly (P < 0.001) higher AUC and RH compared to either glucophage, doanil tablets or enteric coated insulin capsules alone. The results show that enteric-coated insulin capsules can be a replacement of either of the oral hypoglycemic drugs. In addition, the combination of the insulin capsules and glucophage tablets could be a good therapy to Type II diabetic patients that not controlled properly by oral hypoglycemic drugs.