In one study trimethoprim
increased the AUC of single-dose repaglinide
by about 60% without changing its blood glucose lowering effects.
The UK manufacturers advise that concurrent use should be avoided as the effect of larger doses of both drugs are unknown. However, the US manufacturers suggest that repaglinide
dosage adjustments may be necessary. If both drugs are used it would seem prudent to increase the frequency of blood glucose monitoring until the effects are known.