Hemobiological activity of gliclazide in diabetes mellitus

The hemovascular abnormalities encountered in diabetes include platelet alterations, shifts in prostaglandin metabolism and disorders of fibrinolysis. Diabetes is thus associated with increased platelet adhesiveness, increased platelet aggregation with hypersensitivity to proaggregants, increased plasma levels of beta-thromboglobulin and platelet factor 4 as an expression of platelet hyperactivity, increased levels of thromboxane A2 (TXA2) and prostacyclin (PGI2), and reduced levels of tissue plasminogen activator (t-PA). It is not clear which, if any, of these abnormalities are generated by chronic hyperglycemia and can be corrected by adequate glycemic control. Studies with gliclazide have demonstrated that it exerts hemovascular effects which can be valuable to patients. Thus, treatment with gliclazide leads to a decrease in platelet adhesiveness and aggregability. This treatment also reduces thromboxane levels and increases TPA levels. The mechanisms of action of gliclazide are not fully known but it has been demonstrated that its antiplatelet action is independent of its hypoglycemic activity and is not accompanied by clinical abnormalities of blood clotting. The mechanism of direct action on platelet activity may be mediated by inhibition of activated glycogen synthetase, activation of adenylate cyclase, modulation of arachidonic acid release from platelet membranes, stimulation of PGI2 production, and inhibition of the proaggregant action of TXA2. Thus, gliclazide not only has a hypoglycemic action but also improves hemovascular parameters in type 2 diabetes when used at normal therapeutic doses.