Persistent microalbuminuria after treatment with renin-angiotensin axis blockers: causes and results of treatment intensification

Lercanidipine valuable effect on urine protein losses: the RED LEVEL study

OBJECTIVE

The RED LEVEL study (REnal Disease: LErcanidipine Valuable Effect on urine protein Losses) directly compares, in an explorative fashion, the effects of lercanidipine + enalapril and amlodipine + enalapril combinations on renal parameters in hypertensive subjects.

RESEARCH DESIGN AND METHODS

This was a 1 year, prospective, multi-center, randomized, open-label, blinded-endpoint (PROBE) study in hypertensive patients with albuminuria.

MAIN OUTCOME MEASURES

Renal function (albuminuria, serum creatinine, creatinine clearance, estimated glomerular filtration rate and proteinuria); blood pressure.

RESULTS

Albuminuria was significantly reduced, compared with baseline values, with the lercanidipine + enalapril combination over the entire study period; at month 3, month 6 and month 12, changes from baseline were: -162.5 (p-value = 0.0439), -425.8 (p-value = 0.0010), -329.0 (p-value = 0.0011) mg/24 h), respectively. On the other hand, this improvement was not observed with enalapril + amlodipine. Other parameters of renal function such as serum creatinine, creatinine clearance, estimated glomerular filtration rate and proteinuria did not change over the study. Both lercanidipine + enalapril and amlodipine + enalapril significantly reduced systolic and diastolic blood pressure values from baseline all over the study period with no significant differences between groups. Safety outcomes were comparable between the two groups.

CONCLUSIONS

Overall, the results of this explorative study lend support to the anti-albuminuric effect of the lercanidipine + enalapril combination and to the long term renal-protective effects of this combination in patients with hypertension.

The necessity and effectiveness of mineralocorticoid receptor antagonist in the treatment of diabetic nephropathy

Diabetes mellitus is a major cause of chronic kidney disease (CKD), and diabetic nephropathy is the most common primary disease necessitating dialysis treatment in the world including Japan. Major guidelines for treatment of hypertension in Japan, the United States and Europe recommend the use of angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, which suppress the renin-angiotensin system (RAS), as the antihypertensive drugs of first choice in patients with coexisting diabetes. However, even with the administration of RAS inhibitors, failure to achieve adequate anti-albuminuric, renoprotective effects and a reduction in cardiovascular events has also been reported. Inadequate blockade of aldosterone may be one of the reasons why long-term administration of RAS inhibitors may not be sufficiently effective in patients with diabetic nephropathy. This review focuses on treatment in diabetic nephropathy and discusses the significance of aldosterone blockade. In pre-nephropathy without overt nephropathy, a mineralocorticoid receptor antagonist can be used to enhance the blood pressure-lowering effects of RAS inhibitors, improve insulin resistance and prevent clinical progression of nephropathy. In CKD categories A2 and A3, the addition of a mineralocorticoid receptor antagonist to an RAS inhibitor can help to maintain 'long-term' antiproteinuric and anti-albuminuric effects. However, in category G3a and higher, sufficient attention must be paid to hyperkalemia. Mineralocorticoid receptor antagonists are not currently recommended as standard treatment in diabetic nephropathy. However, many studies have shown promise of better renoprotective effects if mineralocorticoid receptor antagonists are appropriately used.

Effect of aldosterone breakthrough on albuminuria during treatment with a direct renin inhibitor and combined effect with a mineralocorticoid receptor antagonist

We have reported observing aldosterone breakthrough in the course of relatively long-term treatment with renin-angiotensin (RA) system inhibitors, where the plasma aldosterone concentration (PAC) increased following an initial decrease. Aldosterone breakthrough has the potential to eliminate the organ-protective effects of RA system inhibitors. We therefore conducted a study in essential hypertensive patients to determine whether aldosterone breakthrough occurred during treatment with the direct renin inhibitor (DRI) aliskiren and to ascertain its clinical significance. The study included 40 essential hypertensive patients (18 men and 22 women) who had been treated for 12 months with aliskiren. Aliskiren significantly decreased blood pressure and plasma renin activity (PRA). The PAC was also decreased significantly at 3 and 6 months; however, the significant difference disappeared after 12 months. Aldosterone breakthrough was observed in 22 of the subjects (55%). Urinary albumin excretion differed depending on whether breakthrough occurred. For the subjects in whom aldosterone breakthrough was observed, eplerenone was added. A significant decrease in urinary albumin excretion was observed after 1 month, independent of changes in blood pressure. In conclusion, this study demonstrated that aldosterone breakthrough occurs in some patients undergoing DRI therapy. Aldosterone breakthrough affects the drug's ability to improve urinary albumin excretion, and combining a mineralocorticoid receptor antagonist with the DRI may be useful for decreasing urinary albumin excretion. When the objective is organ protection in hypertensive patients, a two-pronged approach using combination therapy to inhibit both the RA system and aldosterone may be highly effective.