Potentiation by previous nutrients of glibenclamide-induced insulin release in man. An effect which is counteracted by meal-induced retardation of drug absorption.

We have studied the impact of a previous meal on insulin and glucose responses to the subsequent administration of glibenclamide. Healthy volunteers and NIDDM patients ingested a standard low-carbohydrate breakfast, and glibenclamide was administered 110-120 min later either as an intravenous bolus (12.5 micrograms/kg body wt), or as a tablet (5 mg HB 419). When glibenclamide was administered i.v. the drug raised insulin and lowered blood glucose levels, and previous breakfast potentiated these effects both in healthy volunteers and in NIDDM patients. Conversely when glibenclamide was given as a tablet the drug per se raised C-peptide and lowered blood glucose levels under fasting conditions, whereas the drug had no effect when ingested after breakfast. Measurements of glibenclamide in plasma revealed that previous breakfast delayed the systemic appearance of ingested glibenclamide. We conclude that nutrients sensitize insulin-releasing cells to subsequent stimulation by glibenclamide, thereby aggravate a blood-glucose-lowering effect of the drug. However this effect, which could potentially induce undesirable hypoglycaemia in sulphonylurea-treated diabetics, is counteracted when glibenclamide is taken orally because of a meal-induced decrease in drug absorption.