Aliskiren hypertension tablets. This medication, marketed as Rasilez, is a renin inhibitor drug used to treat hypertension (high blood pressure). Renin is a hormone produced in the kidneys that is part of the renin-angiotensin-aldosterone pathway (RAAS). This pathway controls blood pressure by balancing sodium and potassium levels in the blood and fluid levels in the body. High renin levels can cause high blood pressure.