Abstract: To compare the effects of hydrochlorothiazide(HCTZ) 12.5 mg, losartan 50 mg and Hyzaar (losartan 50 mg/HCTZ 12.5 mg) on decreasing blood pressure and improving endothelia function in patients with essential hypertension, 77 patients with mild or moderate essential hypertension were arranged into three randomized, parallel groups for 4 weeks' treatment with HCTZ, losartan or losartan/HCTZ respectively. Before and after the treatment, seating blood pressure and endothelia function were measured. The result showed that seating blood pressure in groups of HCTZ, losartan or Losartan/HCTZ decreased significantly after antihypertensive treatment compared with before. The reducing degree of the diastolic blood pressure and the average artery blood pressure of group HCTZ and Losartan were significantly lower than that of group losartan/HCTZ. It is suggested that losartan/HCTZ is a good compound antihypertensive drug, which has better effects on decreasing blood pressure and improving endothelial function than that of the HCTZ or Losartan in patients with essential hypertension.

Key words: essential hypertension, losartan, hydrochlorothiazide, hyzaar, endothelia function