Anti-albuminuric effect of losartan versus amlodipine in hypertensive Japanese patients with type 2 diabetes mellitus: A prospective, open-label, randomized, comparative study

Abstract

Background

The antiproteinuric effect of the angiotensin II receptor-antagonist losartan has been observed in patients with type 2 diabetes mellitus (T2DM). Proteinuria is considered to be a predictor of the progression of kidney disease.

Objective

The aims of the present study were to compare and examine the ability of losartan and amlodipine to ameliorate albuminuria in hypertensive Japanese patients (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg) with T2DM and whether the change in albuminuria was associated with a change in glomerular filtration rate (GFR).

Methods

This prospective, open-label, randomized, comparative study was conducted over 3 months at the Kinki University School of Medicine, Osaka-Sayama, Japan. Hypertensive patients with T2DM were enrolled and randomly assigned to 1 of 2 study groups receiving either losartan (25–100 mg/d) or the calcium channel-blocker amlodipine (2.5–5 mg/d). Urinary albumin excretion (UAE), creatinine clearance, and GFR were recorded at study initiation (baseline) and study end (month 3). The GFR was measured from the fractional renal accumulation of ^99mTc-diethylenetriaminepentaacetic acid. Adverse events (AEs) were monitored by a clinical research nurse during the examination.

Results

Fifty patients were asked to enroll and 38 returned the informed written consent. Thirty-five Japanese patients were included in the final study analysis. Seventeen patients were assigned to the losartan group (male sex, 10 [58.8%]; mean [SD] age, 58.1 [8.2] years) and 18 were assigned to the amlodipine group (male sex, 10 [55.6%]; mean [SD] age, 57.4 [8.9] years); no significant between-group difference in demographics was observed. A significant decrease from baseline to month 3 of mean (SD) UAE was observed in the losartan group (352.5 [556.6] mg/d vs 275.7 [466.1] mg/d; P = 0.048). No significant difference in mean (SD) UAE was observed in the amlodipine group for the same time period (298.2 [416.6] mg/d vs 322.7 [415.4] mg/d). There was a statistically significant difference found in the mean (SD) percent change of UAE from baseline to month 3 in the losartan group compared with the amlodipine group (−23.52 [28.42] vs +27.90 [63.51]; P = 0.004). Neither group was associated with a significant change in GFR during the course of the study. No patient discontinued the study due to AEs that were considered, by the investigator, to be possibly or probably associated with study treatment.

Conclusions

Treatment with losartan, but not amlodipine, was associated with a reduction in albuminuria in these hypertensive Japanese patients with T2DM within a period as short as 3 months. Neither drug was associated with a significant change in GFR. Therefore, the reduction of UAE was independent of a change in the GFR.Key Words: albuminuria, hypertension, glomerular filtration rate, losartan, amlodipine