Hepatic effect of sulfonylureas

The sulfonylureas, tolbutamide, tolazamide and acetohexamide significantly diminish uptake of insulin by the isolated perfused rat liver, whereas the nonhypoglycemic metabolite of tolbutamide, carboxytolbutamide, has no such effect. These results suggest that the sustained action of the sulfonylureas may in part be due to reduced hepatic uptake of endogenously secreted insulin.