In vitro activity: Glimepiride inhibits Kir6.2/SUR currents by interaction with two sites: a low-affinity site on Kir6.2 (IC(50)= approximately 400 mM) and a high-affinity site on SUR (IC(50)=3.0 nM for SUR1, 5.4 nM for SUR2A and 7.3 nM for SUR2B). Glimepiride exhibits a higher potency compared to Glibenclamide with respect to stimulation of glucose transport, glucose transporter isoform 4 (GLUT4) translocation and lipid and glycogen synthesis in normal and insulin-resistant adipocytes and in muscle cells, as well as of the potential underlying signalling processes examined at the molecular level. Glimepiride associates in a time- and concentration dependent non-saturable manner with detergent-insoluble complexes of the plasma membrane which may correspond to caveolae. Glimepiride blocks pinacidil-activated whole-cell K(ATP) currents of cardiac myocytes with an IC(50) of 6.8 nM, comparable to the potency of Glibenclamide in these cells. Glimepiride blocks K(ATP) channels formed by co-expression of Kir6.2/SUR2A subunits in HEK 293 cells in outside-out excised patches with a similar IC(50) of 6.2 nM.

Cell Assay: When cultured cells in the presence of a physiological insulin dose and glimepiride (10 μM), 2-deoxyglucose uptake was increased to 186% of control. Glimepiride also increased 2-deoxyglucose uptake in the absence of insulin. At the same time, glimepiride increased the expression of both GLUT1 and GLUT4 to 164% and 148% of control, respectively. These results suggested glimepiride increased cardiac glucose uptake in an insulin-independent pathway.