Renal-protective effect of T-and L-type calcium channel blockers in hypertensive patients: an Amlodipine-to-Benidipine Changeover (ABC) study.

Both strict blood pressure control and efferent artery dilatation are critical in reducing proteinuria, which in turn helps to regulate blood pressure. Benidipine, an L- and T-type calcium channel blocker, has the potential for increased effectiveness compared with L-type-dominant calcium channel blockers such as amlodipine. Therefore, we evaluated blood pressure and proteinuria after changeover from amlodipine to benidipine in poorly controlled hypertensive patients. Fifty-eight hypertensive outpatients undergoing amlodipine treatment and unable to achieve optimal blood pressure as determined by Japanese Society of Hypertension Guidelines for the Management of Hypertention (JSH 2004) were changed over to benidipine treatment. We measured blood pressure and pulse rate and assessed urinary protein excretion before and after changeover. Systolic and diastolic blood pressure dropped from 151/90 mmHg to 140/81 mmHg (p<0.0001). Mean blood pressure (p<0.0001) and pulse pressure (p=0.0069) were also reduced, but pulse rate increased from 75 bpm to 78 bpm (p=0.0047). Urinary protein excretion adjusted for urinary creatinine was reduced from 0.35 +/- 0.82 to 0.22 +/- 0.55 g/g creatinine (p=0.0119). The urinary protein reduction was observed only in patients with renin-angiotensin inhibition (p=0.0216). By switching from amlodipine to benidipine treatment, more than 80% of patients reduced their blood pressure, and more than 40% achieved optimal blood pressure. Higher urinary protein excretion (p<0.0001), lower glomerular filtration rate (p=0.0011) and presence of diabetes (p=0.0284) were correlated with reduction of urinary proteins during changeover. Taken together, our results suggest that benidipine may have greater efficacy than amlodipine in reducing blood pressure and proteinuria.