Cilnidipine exercises an N-type calcium-channel-blocking activity and reduces sympathetic hyperactivity. A study, published in Hypertension Research, compared the effects of cilnidipine and amlodipine on renal function and proteinuria. Twenty-eight proteinuric hypertensive outpatients maintained on calcium channel blockers (CCBs) for more than 3 months were randomized to receive amlodipine besilate (14 patients) or cilnidipine (14 patients). The dosage of these CCBs was increased or other drugs were added until BP decreased below 140/90 mmHg, but no inhibitors of the renin-angiotensin (RA) system were added or changed in dosage. The levels of urine protein, urine albumin, serum and urine creatinine (Cr), and serum beta2-microglobulin were determined before and at 6 and 12 months after randomization. The amlodipine group exhibited a significant increase in proteinuria, while the increase was suppressed in cilnidipine group. The rate of increase in proteinuria at 12 months was 87% of the baseline value in the amlodipine group compared to 4% of baseline with cilnidipine, thus showing a significant intergroup difference. The mean BP was in the range of 96-99 mmHg until 12 months after randomization, with no significant difference between the two groups. Cilnidipine was found to result in a greater suppression of the increase in proteinuria and greater reduction in glomerular filtration rate than amlodipine.