Use of angiotensin receptor blockers in Hypertension
ARBs inhibit the binding of angiotensin II to its subtype 1 receptor, which also results in vasodilation and BP lowering. They do not cause as much cough as ACE inhibitors, and whether they cause angioedema is unclear. Just like ACE inhibitors, ARBs should not be used in pregnancy and only cautiously in the presence of renal artery stenosis. Some ARBs have been approved for type 2 diabetic nephropathy and heart failure with diminished left ventricular function.
Several clinical trials of ARBs have provided disappointing results, either compared with CCBs Valsartan Antihypertensive Long-Term Use Evaluation trial [VALUE] or placebo (TRANSCEND, PRoFESS). The design of these trials has been criticized because either the dose was too low to cause equivalent BP lowering (e.g., VALUE), or the randomized agents were given in addition to other antihypertensive and other preventive therapies rather than as initial treatments (TRANSCEND, PRoFESS). There are no direct comparisons of diuretics with ARBs, because nearly all the ARB trials used a diuretic as second-line therapy. The major advantage of ARBs seems to be their relatively benign adverse effect profile; this probably accounts for why they have the highest persistence rates of all antihypertensive agents in general clinical practice. The combination of an ARB plus an ACE inhibitor was found to lower BP only a little more than either drug alone, not significantly improve clinical outcomes, and be associated with a much higher rate of adverse effects (especially renal) in the ONTARGET trial.