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Home > Drug Category > Blood Pressure Medication (Angiotensin Receptor Blocker) > Hyzaar and Equivalent

Hyzaar (Losartan Potassium and Hydrochlorothiazide) Information

Hyzaar is a combination medication containing two active ingredients: losartan potassium (an Angiotensin II Receptor Blocker or ARB) and hydrochlorothiazide (HCT) (a thiazide diuretic). It is indicated for the treatment of hypertension (high blood pressure) in patients for whom combination therapy is appropriate. This fixed-dose combination is typically used when blood pressure is not adequately controlled with either component alone. Hyzaar is also indicated to reduce the risk of stroke in patients with hypertension and Left Ventricular Hypertrophy (LVH), a benefit demonstrated primarily with the losartan component. Hyzaar is administered orally, typically once daily.

The mechanism of action involves the synergistic effects of the two components: Losartan blocks the binding of Angiotensin II to the AT1 receptor. This inhibits vasoconstriction and aldosterone release, promoting vasodilation (widening of blood vessels) and the excretion of sodium and water, thus reducing systemic vascular resistance. Hydrochlorothiazide (HCT) is a diuretic that works primarily in the distal convoluted tubules of the kidney. It increases the excretion of sodium, chloride, and water, thereby reducing plasma volume. By combining these two mechanisms, Hyzaar provides a more potent and comprehensive reduction in blood pressure than either drug alone, as the diuretic effect of HCT augments the ARB's blood pressure-lowering effect.

Hyzaar Side Effects

Hyzaar combines the side-effect profiles of losartan and hydrochlorothiazide. Common side effects often reported include dizziness, particularly when standing up quickly (orthostatic dizziness), headache, upper respiratory tract infection, back pain, and fatigue. Due to the diuretic component, minor disturbances such as mild hypokalemia (low potassium) or hyperuricemia (which can contribute to gout) may occur.

However, more serious side effects can occur, leading to significant monitoring protocols. If any of the following symptoms are experienced, the patient should stop taking the medication and seek immediate medical attention:
• Angioedema: A rare but severe and potentially life-threatening swelling of the face, lips, tongue, or throat, which can impair breathing. This requires immediate emergency medical attention.
• Fetal Toxicity (Boxed Warning): Use during pregnancy is associated with significant harm to the developing fetus, including fetal death, hypotension, renal failure, and skull hypoplasia. The losartan component necessitates immediate discontinuation of the drug upon confirmed pregnancy.
• Renal Impairment/Failure: In patients whose kidney function is dependent on the renin-angiotensin system (e.g., those with bilateral renal artery stenosis), the combination may cause acute kidney failure or worsening renal function.
• Severe Electrolyte Imbalances: The combination can cause critical imbalances, including hyperkalemia (high potassium, due to the ARB), hypokalemia (low potassium, due to the HCT), hyponatremia (low sodium), or hypercalcemia (high calcium). These imbalances can severely affect heart function.
• Symptomatic Hypotension: Excessive lowering of blood pressure, especially in patients who are volume-depleted, which may lead to fainting (syncope).

Hyzaar Precautions

Due to the risk of fetal harm from the losartan component, Hyzaar carries a Boxed Warning regarding use during pregnancy and must be discontinued as soon as pregnancy is detected. Women of childbearing age should be advised about the risks of use during pregnancy and discuss appropriate contraceptive use or alternative therapies if they are planning to become pregnant. It is contraindicated in patients with a history of hypersensitivity to losartan, sulfonamide-derived drugs (HCT is a sulfonamide), or a history of anuria (inability to urinate). Caution is advised when initiating therapy in patients who are volume-depleted (e.g., those on high-dose diuretics) or salt-depleted, as they are at a greater risk for symptomatic hypotension, which may require correction before starting the drug. The concurrent use of Hyzaar with the drug aliskiren is contraindicated in patients with diabetes or moderate to severe renal impairment (GFR less than 60 millilitres per minute). Due to the diuretic component, patients prone to electrolyte disturbances, gout, or lupus should be monitored carefully.

Do I need a prescription to order Hyzaar?

Yes, a prescription is required from your physician to order Hyzaar.