• The change of 24-hour, one day systolic BP standard deviation (SD) within subjects (the difference of SD before and after 12 weeks' treatment) in lacidipine group and losartan group
  

• The change of 24-hour, one day diastolic BP standard deviation (SD) within subjects (the difference of SD before and after 12 weeks' treatment) in lacidipine group and losartan group
  
• The difference of the changes in office diastolic and systolic BP after 12 weeks' treatment between lacidipine group and losartan group
  
• The difference of the mean 24-hour ABPM systolic and diastolic BP after 12 weeks' treatment between lacidipine group and losartan group
  
• The difference of the diastolic and systolic BP control rates after treatment between the 2 groups
  
• The difference of the changes in 24-hour, one day BP standard deviation (SD) within subjects between lacidipine group and losartan group
  
• The difference of the variation of coefficient (CV) of the mean values (24-hour BP SD divided by the mean multiplied by 100) between 2 groups
  
• The difference of the smoothness index (SI, dividing the average of the 24 hourly change after treatment by the corresponding standard deviation) between 2 groups
  
• The difference of the changes in pulse pressure after treatment between the 2 groups
  

Drug: lacidipine (4 mg) or losartan (50 mg)
lacidipine (4 mg) or losartan (50 mg), both given once daily at the same hour in the morning (approximately at 8 AM) for 12 weeks

In this study, we investigate the effects of two anti-hypertensive medications on systolic BP variability profile as a pilot study. This is a prospective, randomized, open-label, blinded end point (PROBE), parallel group study with two treatment arms. At the end of an initial 2-week washout period, during which any eventual anti-hypertensive drug is discontinued, patients fulfilling the inclusion criteria are randomly treated with the lacidipine (4 mg) or losartan (50 mg), both given once daily at the same hour in the morning (approximately at 8 AM) for 12 weeks. If the BP goal (SBP < 140 mmHg and DBP < 90 mmHg) has not been attained after 4 week's treatment, 12.5 mg hydrochlorothiazide (HCTS) once daily can be added.

Patients are checked 24-h ambulatory BP monitoring (ABPM) at the end of the washout period and after 12 weeks of active treatment. At each visit, seated cuff SBP and DBP, heart rate, use of concomitant medication and spontaneously reported adverse events are recorded.