It is difficult to control morning hypertension in practical clinical situation. Angiotensin
receptor blocker (ARB) and thiazide are suggested to be effective to maintain the
antihypertensive effects for 24 hours. However, monotherapy sometimes is not enough to
control blood pressure level in the next morning and there are little evidence of the
combination therapy for morning hypertension. The investigators hypothesized that a losartan
50 mg/hydrochlorothiazide 12.5 mg combination drug, Preminent, is effective and safe for
controling morning hypertension, compared with high-dose of losartan 100 mg, in Japanese.
Patients with morning hypertension were randomized to preminent treatment group or high-dose
losartan treatment group. The efficacy and safety were compared after 3-month treatment.