Aliskiren

Aliskiren is the fourth class of pharmacological agents that modify the function of RAAS. It is an octanamide, is the first known representative of a new class of completely nonpeptide, low-molecular-weight, orally active transition-state renin inhibitors. Aliskiren has good water solubility and low lipophilicity, and is resistant to biodegradation by peptidases in the intestine, blood circulation, and the liver. Aliskiren has 10,000-fold higher affinity for renin than for other aspartic peptidases^[1].

In short-term studies, Aliskiren is effective in lowering blood pressure either alone or in combination with valsartan and hydrochlorothiazide, and had a low incidence of serious adverse effects. Aliskiren has a half-life of approximately 40 h, making it suitable for once-daily dosing, with less potential for loss of efficacy between doses than shorter acting agents. Aliskiren exhibits oral bioavailability due to its low molecular weight (609.8 Da) and nonpeptide structure, making it more resistant to gastrointestinal enzyme disintegration. However, it is still poorly absorbed (oral bioavailability, ∼2.5%). Aliskiren is 50% protein bound, and the apparent volume of distribution is 135 L. Aliskiren is slightly metabolized in humans (about 20%) and is approximately 50% metabolized in rodents. Aliskiren effectively reduces functional plasma renin activity by binding to renin with high affinity, preventing it from converting angiotensinogen to angiotensin I. The inhibition of renin by aliskiren is associated with a reduction in circulating levels of angiotensin I and II, with a resultant increase in plasma renin concentration and inhibit activation of mitogen-activated protein kinases ERK1 (p44) and ERK2 (p42). It prevents hypertrophy and proliferation. Aliskiren is well tolerated, with the most common adverse events reported as headache, dizziness, and fatigue^[1].

• [1] Pranay Wal, et al. J Pharm Bioallied Sci. 2011, 3(2): 189–193.