Effect of the Angiotensin II Receptor Antagonist Irbesartan on Biochemical and Functional Markers of Endothelial Dysfunction in Patients With Hypertension

Primary: * To evaluate the impact of irbesartan on endothelial function in hypertensive patients with metabolic syndrome. Secondary: * To evaluate the oxidative stress status in patients with hypertension with metabolic syndrome. * To correlate the oxidative stress status with endothelial function in these patients. * To evaluate the effect of irbesartan on the oxidative stress stage in patients with metabolic syndrome and to correlate it with the effect on endothelial function . * To correlate the change in endothelial function and oxidative stress stage with the change of arterial pressure levels.