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What Are ACE Inhibitor Drugs?
ACE Inhibitors and the Renin-Angiotensin System
The acronym ACE stands for "Angiotensin-Converting Enzyme." According to the Mayo Clinic, ACE inhibitors are a class of drugs that doctors prescribe for the treatment of health problems that include high blood pressure, coronary artery disease and migraines. Examples of ACE inhibitors include enalapril (Vasotec), captopril and benazepril (Lotensin). In order to fully understand what ACE inhibitor drugs are, you must first understand an enzyme system in the body called the renin-angiotensin system.
When the amount of salt and water flowing into the kidney is insufficient, blood flow to the kidney (renal blood flow) can drop to a level that is too low. Conditions such as diarrhea, vomiting and excessive perspiration are things that might cause salt and water flow to the kidney to decrease. Blood flow to the kidney can also decrease because of the narrowing of a renal artery by the build up of plaque. In response to low renal blood flow, special cells in the kidney will secrete an enzyme called renin into the blood. Renin then catalyzes the conversion of a blood protein called angiotensinogen into a peptide (small protein) called angiotensin I. Angiotensin-converting enzyme or ACE then acts on angiotensin I to tranform it into a another peptide called angiotensin II. The presence of angiotensin II in the blood does two things: it leads to an increase in the amount of salt and water taken up by the kidneys and it constricts small arteries. The constriction of small arteries causes an elevation of blood pressure. ACE inhibitor drugs lower blood pressure because they are preventing the tranformation of angiotensin I into angiotensin II.
Side Effect Profile of ACE Inhibitors: The Growing Concern About Angioedema
For over 30 years, doctors have been prescribing ACE inhibitors to patients with hypertension, heart disease, stroke and other conditions, and the drugs have been generally well tolerated. According to the Mayo Clinic, common side effects of ACE inhibitors include dry cough, rapid heartbeat, headaches, dizziness, rash, fatigue and hyperkalemia (increased blood-potassium levels).
Over the years, the number of patients taking the drugs has increased significantly. In 2011, 162 million prescriptions for ACE inhibitors were written for tens of millions of Americans, according to the healthcare information company IMS Health. This increase in the number of patients taking the drugs has led to an increase in the number of occurrences of a rare side effect known as angioedema, a swelling of certain tissues in the body. Angioedema can be life threatening if the swelling occurs in the tongue or throat. The frequency of angioedema has gotten to a point at which it has attracted the attention of the medical community. In an article in the May 1, 2012, edition of "The Philadelphia Inquirer," Dr. James R. Roberts, director of emergency medicine at Mercy Philadelphia Hospital and Mercy Fitzgerald Hospital, reported that the emergency rooms at his hospitals are getting about one case of ACE inhibitor-related angioedema each week. He wants the U. S. Food and Drug Administration to put a "black-box warning" on the prescribing information for ACE inhibitors so that doctors will be reminded to warn patients about the possibility of angioedema.
Disclaimer: This hub has been written for the sole purpose of providing information to the reader. It is not intended to be a source of any kind of medical advice or instruction, and it should not be used in the diagnosis of any illness, disease or condition. You should consult your doctor if you have questions about a specific medical problem.