A renin antagonist is a compound that inhibits the secretion of renin from the kidneys. Renin, an enzyme, is a key part of the renin-angiotensin system (RAS), a system used by the human body to regulate blood pressure. Pharmaceutical companies use renin antagonists in medications designed to treat hypertension, a condition caused by an overproduction of renin that leads to high blood pressure. A similar type of medication known as angiotensin-converting enzyme (ACE) inhibitors also interrupt the RAS, though they do not affect renin specifically.
Kidneys and the renin they produce help maintain normal blood pressure. The kidneys either retain or release water and salts. Renin, when produced, acts upon the body to create a temporary spike in blood pressure. This action is a key feature in the body's "fight or flight" response. Yet when hypertension occurs, the body produces too much renin; blood pressure remains high.
Hypertension can have many negative long-term effects on the body. The chances of heart attack and stroke go up, especially if an individual has a pre-existing condition like diabetes. Kidney failure is another possibility, as high blood pressure puts strain on the kidneys. Though a number of lifestyle changes can help ease hypertension, a renin antagonist stops hypertension at its source: the production of renin.
Though medication to treat hypertension has existed for many years, those based on a renin antagonist have only been available since 2007. Aliskiren was the first renin inhibitor approved for human use. Aliskiren and medications like it target the kidneys' juxtaglomerular cells, those responsible for the secretion of renin. A single dose is effective for 24 hours. As of the summer of 2011, no medical evidence has shown that aliskiren or other, newer renin antagonists have any negative effects on the kidneys.
Hypertension medications based on a renin antagonist are not the only ones that affect the RAS. Medications known as ACE inhibitors affect the RAS as well, though at a different place in the RAS cycle. Though a renin antagonist will completely stop the RAS from starting, ACE inhibitors interrupt the process halfway. The compound angiotensin I is unable to convert to angiotensin II because of the ACE inhibitor.
The overall effect of both types of medications is identical. As ACE inhibitors have existed longer than renin antagonists, the medical community better understands their side effects and drug interactions. Individuals considering taking a renin antagonist should consult their physicians, as the same side effects and drug interactions of ACE inhibitors may also apply to renin antagonists.