One in three Americans suffer from hypertension, or high blood pressure. Uncontrolled hypertension increases your risk for heart attack and stroke. Some people with hypertension can control their blood pressure by losing weight, exercising and decreasing their salt consumption, but many have to take medications as well. Losartan potassium, or simply losartan, is one of many medications used to control high blood pressure.
Definition
Your blood pressure is represented as two numbers. The first --- systolic pressure --- measures the pressure that is generated in your arteries when your heart contracts. The second, is diastolic, which measures the pressure in your arteries when your heart rests between beats. If your systolic blood pressure is 140 or higher, or if your diastolic blood pressure is 90 or higher, you have hypertension. Medications such as losartan are prescribed for treating elevations of either systolic or diastolic blood pressure.
Causes
"The Merck Manual of Diagnosis and Therapy" reports that 85 to 95 percent of all cases of hypertension are "primary," meaning they have no known cause. The remaining cases result from kidney disease, metabolic disorders, blood vessel abnormalities, substance abuse or other identifiable causes. Measurement of different physiological parameters in hypertensive people reveals that primary hypertension is unlikely to have a single cause. Many hypertensive patients exhibit imbalances in a hormonal system called the renin-angiotensin-aldosterone system, or RAAS. Losartan helps to lower blood pressure in such patients.
Hormonal Regulation
The RAAS controls your blood pressure by regulating your blood volume, heart rate and blood vessel diameter. When your kidneys sense a drop in your blood volume, they produce an enzyme called renin. Renin converts a circulating protein called angiotensinogen to angiotensin I, and angiotensin I is transformed to angiotensin II by yet another enzyme in your lungs. Angiotensin II is a hormone with multiple functions. By stimulating receptors that trigger blood vessel constriction and aldosterone secretion, angiotensin II elevates your blood pressure. According to the U.S. Food and Drug Administration, losartan inhibits the actions of angiotensin II by blocking its attachment to receptors in your blood vessels and other tissues.
Considerations
Losartan belongs to a class of drugs called angiotensin II receptor antagonists. It effectively inhibits angiotensin II's ability to stimulate receptors in your blood vessels, adrenal glands and brain, thereby blunting angiotensin II's pressure-raising effects.
Like nearly any medication, losartan can cause side effects, and it may interact with other drugs or supplements. Losartan can increase your potassium levels, so you should consult with your doctor before taking potassium supplements or other medications that increase potassium levels. Pregnant women should not take losartan or similar medications due to an increased risk for fetal harm.
References
- U.S. Centers for Disease Control and Prevention: High Blood Pressure Fact Sheet
- "The Merck Manual of Diagnosis and Therapy, 18th Edition: Arterial Hypertension"; Mark H. Beers, M.D., Editor-in-Chief; 2006
- Drugs.com: Losartan
