Hyperglycaemia and absorption of sulphonylurea drugs

To examine whether hyperglycaemia impairs the absorption of sulphonylurea agents, glipizide, which is rapidly and completely absorbed, was measured in plasma from 12 healthy young subjects during various levels of experimentally-induced hyperglycaemia. An increase in the plasma glucose concentration above 7 mmol/l was associated with a dose-dependent delay in the absorption of glipizide; at a concentration above 11 mmol/l, the plasma glipizide concentration was reduced by 50%. The data indicate that hyperglycaemia may delay the absorption of sulphonylurea agents, probably because it impairs gastric motility and/or gastric emptying. This delay of absorption may be clinically relevant, since the efficacy of short-acting sulphonylureas is dependent upon the absorption rate of the drug.