The antihyperglycemic drug metformin and the thrombocyte aggregation inhibitor dipyridamole
are often used concomitantly in patients with diabetes who have suffered a transient ischemic
attack or stroke. It has recently been suggested that the gastrointestinal absorption of
metformin is mediated by the equilibrative nucleoside transporter 4 (hENT4). Dipyridamole has
been reported to inhibit hENT4 transport in vitro. The aim of this research proposal is to
study the pharmacokinetic interaction between metformin and dipyridamole. The investigators
hypothesize that dipyridamole reduces the gastrointestinal absorption of metformin. If this
hypothesis can be confirmed, then the results of this study can explain in part the high
variability in plasma metformin concentrations in patients treated with diabetes, and can be
used to optimize pharmacotherapy in patients with diabetes.