Antioxidative effects of benidipine hydrochloride in patients with hypertension independent of antihypertensive effects. Relationship between blood pressure and oxidative stress.

This study investigated the significance of measuring plasma level of thiobarbituric acid reactive substance (TBARS) in patients with hypertension and compared the clinical effects of benidipine hydrochloride (CAS 91599-74-5, Coniel) and amlodipine besylate (CAS 111470-99-6) on plasma TBARS. At first, blood pressure and plasma TBARS were measured in 85 untreated patients (48 males and 37 females, 68 years old on average) with at least one risk factor of cardiovascular disease to investigate factors which had influence on plasma TBARS. As the result, plasma TBARS was significantly higher in those with hypertension, which was also true when adjusted for other factors (r = 0.359, p< 0.01). Among these patients, benidipine hydrochloride at the dose of 4 mg/day was administered to 49 patients with hypertension or angina pectoris. All patients stratified for each factor showed significantly decreased plasma TBARS after benidipine hydrochloride treatment. Second, 40 untreated patients with essential hypertension were randomly assigned to the amlodipine group (5-7.5 mg/day) or benidipine group (4-8 mg/day) to compare the plasma TBARS levels. Plasma TBARS levels were significantly decreased in both groups. The amlodipine group showed a positive correlation between the decrease in plasma TBARS level and those in both diastolic and systolic blood pressures after treatment. On the other hand, benidipine hydrochloride decreased plasma TBARS to a greater degree than both diastolic and systolic blood pressures. These findings suggest that patients with hypertension have high plasma TBARS, and benidipine hydrochloride decreases not only blood pressure but also oxidative stress in the clinical practice.