[Renoprotective effect of triple therapy with low-dose angiotensin receptor blocker, low-dose diuretic and Ca-antagonist in hypertensive type 2 diabetic patients with overt nephropathy].

Combination therapy with angiotensin receptor antagonist(ARB) plus angiotensin converting enzyme inhibitor(ACE-I) (ARB/ACE-I) was efficacious in reducing proteinuria in patients with progressive renal disease. However, this therapy may be associated with the worsening of anemia and hyperkalemia. The present study addressed whether or not triple therapy with low-dose ARB, low-dose diuretic (D) and calcium channel blocker(CCB) (ARB/D/CCB) is as effective as therapy with low-dose ARB/ACE-I in retarding the progression of overt diabetic nephropathy. In the triple therapy, the patients were initially subjected to monotherapy with CCB for 24 weeks. Low-dose ARB and low-dose D were added to the treatment for an additional 24-week period. In parallel, patients undergoing double therapy were initially treated with low-dose ACE-I alone for 24 weeks, and then low-dose ARB was added for an additional 24-week period. The results were as follows: 1) In the triple therapy, blood pressure was reduced by 9 mmHg in systole and 5 mmHg in diastole (not significant) compared to monotherapy with CCB. There was a significant decline in proteinuria (3.3 +/- 1.2 g/day in the CCB-treated period vs. 2.1 +/- 1.0 g/day in the ARB/D/CCB-treated period, n = 12, p = 0.0143). Furthermore, a significant improvement in the slope of reciprocal serum creatinine concentration(1/Cr) was found in response to triple therapy(1/Cr: -0.0118 +/- 0.0009 in the CCB-treated vs. -0.0035 +/- 0.0028(I/mg/dl/month) in the ARB/D/CCB-treated period, n = 12, p < 0.001). There was neither a worsening of anemia nor an increase in the serum potassium(K) concentration. 2) In the double therapy, blood pressure was reduced by 12 mmHg in systole(p = 0.0079, n = 11) and 6 mmHg in diastole(n = 11, p = 0.0037) compared to the monotherapy with ACE-I. A significant improvement in the slope of 1/Cr was found in the double therapy(1/Cr: -0.0095 +/- 0.0052 in the ACE-I treated period vs. -0.0029 +/- 0.0028(I/mg/dl/month) in the ARB/ACE-I, n = 11, p < 0.001). In addition, there was a substantial reduction in hematocrit and increase in serum K concentration. The present result suggests that triple therapy consisting of ARB/D/CCB is as efficacious as double therapy with ARB/ACE-I in protecting the kidney from the progression in patients with diabetic overt nephropathy. The former may be expected to have less adverse effects.