losartan and hydrochlorothiazide, Hyzaar

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

What is losartan and hydrochlorothiazide, and how does it work (mechanism of action)?

Hyzaar is a combination of losartan (Cozaar) and hydrochlorothiazide and is used for treating high blood pressure. Losartan is an oral medication that belongs to a class of drugs called angiotensin receptor blockers (ARBs). Other ARBs include irbesartan (Avapro), valsartan (Diovan), and candesartan (Atacand). Angiotensin, formed in the blood by the action of angiotensin converting enzyme (ACE), is a powerful chemical that attaches to angiotensin receptors found in many tissues but primarily on smooth muscle cells surrounding blood vessels. Angiotensin's attachment to the receptors causes the muscles to contract and the blood vessels to narrow (vasoconstrict) which leads to an increase in blood pressure (hypertension). Losartan (more specifically, the chemical formed when the liver converts the inactive losartan into an active chemical) blocks the angiotensin receptor. By blocking the action of angiotensin, losartan relaxes the muscles, dilates blood vessels and thereby reduces blood pressure.

Hydrochlorothiazide (HCTZ) is a diuretic (water pill) used for treating high blood pressure (hypertension) and accumulation of fluid. It works by blocking salt and fluid reabsorption in the kidneys, causing an increased amount of urine containing salt (diuresis). The mechanism of its action in lowering high blood pressure is not well understood. The combination of losartan and HCTZ reduces blood pressure better than either drug alone. Losartan increases potassium levels while HCTZ reduces potassium levels; the combination of both drugs has less effect on potassium levels. The FDA approved Hyzaar in April 1995.

What brand names are available for losartan and hydrochlorothiazide?

Hyzaar

Is losartan and hydrochlorothiazide available as a generic drug?

GENERIC AVAILABLE: Yes

Do I need a prescription for losartan and hydrochlorothiazide?

Yes

What are the side effects of losartan and hydrochlorothiazide?

Common side effects of Hyzaar are:

Other important side effects that may be caused by Hyzaar include:

Hyzaar may reduce kidney function in some patients and should not be used by patients who have bilateral renal artery stenosis (narrowing of both arteries going to the kidneys). Rare cases of rhabdomyolysis (muscle breakdown), hepatitis, ,reduced number of platelets, and pancreatitis have been reported.

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