Effect of combining an ACE inhibitor and an angiotensin II receptor blocker on plasma and kidney tissue angiotensin II levels

Intrarenal angiotensin II and hypertension

Elevations in intrarenal angiotensin II (Ang II) cause reductions in renal function and sodium excretion that contribute to progressive hypertension and lead to renal and vascular injury. Augmentation of intrarenal Ang II occurs by several processes, leading to levels much greater than can be explained from the circulating levels. In Ang II-dependent hypertension, Ang II is internalized via an AT1 receptor mechanism, but there is also sustained intrarenal production of Ang II. Ang II exerts a positive feedback action on intrarenal angiotensinogen (AGT) mRNA and protein. The increased intrarenal AGT production is associated with increased intrarenal and intracellular Ang II contents and urinary AGT excretion rates. The increased urinary AGT indicates spillover of AGT into distal nephron segments supporting enhanced distal Ang II formation and sodium reabsorption. The augmentation of intrarenal Ang II provides the basis for sustained actions on renal function, sodium excretion, and maintenance of hypertension.

Additive effect of ACE inhibition and angiotensin II receptor blockade in type I diabetic patients with diabetic nephropathy

Albuminuria and hypertension are predictors of poor renal and cardiovascular outcome in diabetic patients. This study tested whether dual blockade of the renin-angiotensin system (RAS) with both an angiotensin-converting enzyme (ACE) inhibitor (ACE-I) and an Angiotensin-II receptor blocker (ARB) is superior to either drug alone in type I diabetic patients with diabetic nephropathy (DN). A randomized double-blind crossover trial was performed with 8-wk treatment with placebo, 20 mg of benazepril once daily, 80 mg of valsartan once daily, and the combination of 20 mg of benazepril and 80 mg of valsartan. Twenty type I diabetic patients with DN were included. At the end of each treatment period, albuminuria, 24-h BP, and GFR were measured. Eighteen patients completed the study. Placebo values were: albuminuria [mean (95% CI)], 701 (490 to 1002) mg/24 h; BP [mean (SEM)], 144 (4)/79 (2) mmHg, and GFR [mean (SEM)], 82 (7) ml/min per 1.73 m(2). Treatment with benazepril, valsartan, or dual blockade significantly reduced albuminuria and BP compared with placebo. Benazepril and valsartan were equally effective. Dual blockade induced an additional reduction in albuminuria of 43 % (29 to 54 %) compared with any type of monotherapy, and a reduction in systolic BP of 6 (0 to 13) mmHg and 7 (1 to 14) mmHg (versus benazepril and valsartan, respectively) and a reduction of 7 (4 to 10) mmHg diastolic compared with both monotherapies. GFR was reversibly reduced on dual blockade compared with monotherapy and placebo. All treatments were safe and well tolerated. In conclusion, dual blockade of the RAS may offer additional renal and cardiovascular protection in type I diabetic patients with DN.

Appropriate drug therapy for improving outcomes in diabetic nephropathy

Diabetic nephropathy is the leading cause of end-stage kidney disease in the United States. The majority of these cases are attributed to those with type 2 diabetes. Elevated blood pressure, proteinuria, and increased activity of the renin-angiotensin-aldosterone system (RAAS) play a major role in the development and progression of chronic kidney disease attributed to diabetes mellitus. Moreover, drugs that inhibit angiotensin II synthesis or block the angiotensin II type I receptor lower blood pressure, reduce proteinuria, and improve outcomes in patients with chronic kidney disease caused by diabetes. This article highlights improvements in the current management of diabetic nephropathy afforded by agents that inhibit the RAAS, discusses their limitations, and considers novel strategies to prevent onset and progression of diabetic nephropathy. Current opinions concerning combination drug therapy with agents that block the RAAS at multiple sites, as well as combining calcium channel blockers with either angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists, are also discussed.

The practical aspects of combination therapy with angiotensin receptor blockers and angiotensin-converting enzyme inhibitors

Angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin receptor blockers (ARBs) are widely prescribed for the management of hypertension. ACE inhibitors (ACE-I) and, more recently, ARBs have an established track record of success in the treatment of congestive heart failure (CHF), proteinuric renal disease and most recently the hypertensive patient with a high cardiac-risk profile. The individual success of each of these drug classes has fuelled speculation that given together the overall effect of both would exceed that of either given alone. This premise, although biologically plausible, has yet to be proven in a convincing enough fashion to support the routine use of these two drug classes in combination. Additional clarifying studies are needed to establish whether specific patient subsets exist that might benefit from such combination therapy.