Direct Renin Inhibition: Focus on Aliskiren

BACKGROUND: Despite the availability of many effective, well-tolerated drugs, a significant proportion of treated hypertensive patients still have uncontrolled high blood pressure (BP) and thus face serious morbidity and mortality. The renin-angiotensin aldosterone system (RAAS) is a key target for BP control and for cardiovascular and renal protection. Renin controls the rate-limiting step in the RAAS cascade and hence is the optimal target for RAAS suppression. Aliskiren is the first direct renin inhibitor (DRI) to be approved by the U.S. Food and Drug Administration and the European Medicines Agency for treating hypertension. OBJECTIVE: To provide an overview of the pharmacology, pharmacokinetics, preclinical, and clinical efficacy and safety data on the DRI aliskiren. RESULTS: Approximately 70% of essential hypertension is associated with elevated renin levels. Aliskiren is a potent and highly specific inhibitor of renin, with oral bioavailability of 2.6% and an elimination half-life of 40 hours, making it suitable for once-daily oral administration. Aliskiren dose-dependently reduced BP, inhibited plasma renin activity (PRA), attenuated renal damage in animal models, and showed efficient and longer- lasting blockade of the RAAS in normotensive human subjects compared with other RAAS inhibitors. The clinical efficacy and safety of aliskiren have been evaluated both as monotherapy and in combination with other antihypertensive agents in phase II and phase III trials of patients with mild to severe hypertension. When used as monotherapy, aliskiren led to significant dose-dependent reductions in BP from baseline that were greater than those obtained with placebo and comparable with those achieved with an angiotensin II receptor blocker (ARB). The combination of aliskiren with a diuretic, a calcium channel blocker (CCB), an angiotensin-converting enzyme inhibitor (ACEI), or an ARB generally had greater and longer-lasting BP-lowering efficacy than did single agents alone. Aliskiren also countered the reactive increase in PRA caused by diuretic, CC B, ACEI, and ARB therapy. Once-daily treatment with aliskiren was well tolerated. CONCLUSIONS: As a DRI, aliskiren blocks the RAAS more completely than do other current downstream RAAS inhibitors. When used once daily, aliskiren is a safe and effective antihypertensive agent that can be used as monotherapy or in combination with other agents to provide additional options to improve BP control.