Cozaar is a prescription medication used to treat hypertension, or high blood pressure. In addition to treating hypertension, the "Physicians' Desk Reference" indicates that Cozaar is approved for preventing progression of kidney damage due to type 2 diabetes. Known generically as losartan, Cozaar belongs to a class of drugs called angiotensin receptor blockers, or ARBs. Cozaar's chemical activity in your body can cause your serum potassium level to rise, so you should not take potassium with Cozaar unless your doctor advises you to do so.
Renin-Angiotensin System
Your blood pressure is regulated by a variety of mechanisms, but one of the most prominent involves the production of renin, a hormone secreted by your kidneys whenever blood flow to these organs decreases. Renin enters your bloodstream, where it converts a circulating protein called angiotensinogen to angiotensin I. Angiotensin I is then converted to angiotensin II by an enzyme -- angiotensin-converting enzyme -- found in your lungs and other tissues. Angiotensin II stimulates receptors in your blood vessels that trigger arterial constriction, which increases your blood pressure. Angiotensin II also stimulates the release of aldosterone, a hormone that affects potassium levels, from your adrenal glands.
Aldosterone
Your adrenal glands, which perch like caps atop your kidneys, produce hormones that influence a variety of bodily functions, including your metabolic rate, fluid balance, blood glucose level and nervous system activity. Aldosterone, secreted from the outer layer of your adrenal glands, plays an important role in the movement of water and electrolytes through your tissues. One of aldosterone's primary effects is to increase excretion of potassium through your kidneys. By reducing aldosterone production, Cozaar interferes with potassium excretion.
Hyperkalemia
Since Cozaar and other ARBs interfere with the elimination of potassium through your kidneys, taking a potassium supplement or a potassium-containing salt substitute along with Cozaar could increase your serum potassium concentration above normal levels. According to "The Merck Manual of Diagnosis and Therapy," this condition, known as hyperkalemia, is often asymptomatic until cardiac toxicity develops. Thus, the first sign of hyperkalemia could be fatal cardiac arrest.
Considerations
Cozaar is an effective anti-hypertensive medication, and it is usually well-tolerated. However, like most drugs, it can interact with other medications or dietary supplements. Since Cozaar interferes with your kidneys' ability to excrete potassium, consuming supplemental potassium while taking this drug could lead to dangerous elevations in your serum potassium level. This could be especially problematic if your kidney function is already impaired, which often occurs in diabetic patients. If you are taking Cozaar, do not take supplemental potassium unless your physician instructs you to do so.
References
- "Physicians' Desk Reference, 60th Edition: Cozaar"; Lori Murray, Senior Editor; 2006
- "The Merck Manual of Diagnosis and Therapy, 18th Edition: Hyperkalemia"; Mark H. Beers, M.D., Editor-in-Chief; 2006
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