Combination of half doses of angiotensin type 1 receptor antagonist and angiotensin-converting enzyme inhibitor in diabetic nephropathy

BACKGROUND: To investigate the renoprotective effect of combination therapy with an angiotensin I converting enzyme inhibitor and an angiotensin type I receptor blocker (ARB) on diabetic kidney disease, half doses of each monotherapy were given to type 2 diabetic patients with albuminuria. METHODS: Urinary albumin index (UAI) and blood pressure (BP) were measured in a total of 27 outpatients with type 2 diabetes mellitus receiving 10 mg imidapril or 8 mg candesartan per day. Either agent was then substituted with a combination of 5 mg imidapril and 4 mg candesartan. After 3 months of combination therapy, UAI and BP were measured. Changes in the parameters were assessed by paired t test. RESULTS: Although BP was not significantly different prior to and at the end of combination therapy, log-transformed UAI was significantly reduced (P = 0.003) from an initial UAI (mean log-transformed UAI +/- SD) of 79.4 (27.4-231)mg/g Cre to 52.5 (17.1-161)mg/g Cre at the end of combination therapy. The reduction was not associated with the initial UAI, initial BP, decrease in BP, pretreatment medication or other concomitant antihypertensive agents. CONCLUSIONS: In patients with type 2 diabetes and nephropathy, dual blockade of the renin system with an angiotensin-converting enzyme inhibitor and angiotensin receptor blocker significantly reduces albuminuria and, thus, may be renoprotective even when the doses of the agents are reduced by one half.