Comparative effect of canrenone or hydrochlorothiazide addition to valsartan/amlodipine combination on urinary albumin excretion in well-controlled type 2 diabetic hypertensive patients with microalbuminuria

Objective: To compare the effect of adding canrenone or hydrochlorothiazide (HCTZ) to valsartan/amlodipine combination on urinary albumin excretion (UAE) in microalbuminuric type 2 diabetic hypertensives. Research design and methods: After a 2-week placebo period and after 4 weeks of valsartan 160 mg plus amlodipine 5 mg combination, 120 patients whose blood pressure (BP) was not controlled (> 130/80 mmHg) were randomized to canrenone 25 mg or HCTZ 12.5 mg in addition to the previous therapy for 24 weeks. After the first 6 weeks of triple therapy, canrenone or HCTZ doses were doubled in the patients whose BP was yet uncontrolled. At the end of each period (placebo, dual combination and triple combination therapy), clinic and ambulatory BP measurements were recorded and 24 h UAE was evaluated. Results: Both triple combinations produced greater clinical and ambulatory BP reduction than dual therapy, with no difference between the two groups. UAE was reduced by both regimens, but the decrease associated with canrenone add-on therapy was more pronounced. At week 24, UAE decreased by 45.3% in the canrenone group and by 20.3% in the HCTZ group (p <0.01). Conclusions: These findings indicate that, despite similar BP-lowering effect, the addition of canrenone to valsartan/amlodipine combination was more effective in reducing UAE than HCTZ addition.