Abstract: Thirty patients with mild to moderate essential hypertension were treated with losartan(50 mg/d)for 4 weeks. Clinical blood pressure(CBP)and ambulatory blood pressure monitoring(ABPM)were performed at before and after the treatment to compare the mean blood pressure of 24 h, daytime and night, the load of the blood pressure and the circadian rhythm. Results: CBP, the load of blood pressure and the mean blood pressure of 24 h, daytime and night were significantly reduced. No significant difference was found in heart rate. The effective rate dependent CBP was 70.0%. There were significant decreases in every hour blood pressure. There was less effect on night blood pressure, but the circadian rhythm wasn′t significantly changed. The trough to peak ratios for SBP and DBP were more than 70%. The result shows that losartan could significantly and safely decrease the blood pressure. It might maintain normal circadian rhythm of the blood pressure.

Key words: losartan, hypertension, ambulatory blood pressure