[Timing of administration of sulfonyl urea derivatives]

In daily practice the optimal time of administration of sulphonylurea derivatives is not always clear. Administration 30 minutes prior to meals allegedly offers the advantage that an active plasma level has been reached when food enters the gastrointestinal tract. Alleged disadvantages are higher risk of hypoglycaemia and poor compliance. In publications from Medline 1966-1999 the 24-hour availability of sulphonylurea derivates was the same after administration at different times. The absorption rate of glibenclamide and tolbutamide was not affected by food. Study results concerning gliclazide were contradictory. The absorption rate of glipizide was reduced after ingestion during breakfast. In several, partly the same, small studies the findings concerning the variation of the glucose level in time in patients with type 2 diabetes mellitus were equivocal. The pharmacokinetic and pharmacodynamic evidence that sulphonylurea derivatives should be taken 30 minutes before meals appears to be so limited that in our opinion it is out-weighed by the potential risk that this advice may compromise the drug compliance of users.