Hyzaar (Losartan Potassium-Hydrochlorothiazide) Drug Information

  • Why is this medication prescribed?

    HYZAAR is indicated for the treatment of hypertension. This fixed dose combination is not indicated for initial therapy of hypertension, except when the hypertension is severe enough that the value of achieving prompt blood pressure control exceeds the risk of initiating combination therapy in these patients

  • How should this medicine be used?

    Dosing must be individualized. The usual starting dose of losartan is 50 mg once daily, with 25 mg recommended for patients with intravascular volume depletion (e.g., patients treated with diuretics) and patients with a history of hepatic impairment. Losartan can be administered once or twice daily at total daily doses of 25 to 100 mg. If the antihypertensive effect measured at trough using once-a-day dosing is inadequate, a twice-a-day regimen at the same total daily dose or an increase in dose may give a more satisfactory response.

    Hydrochlorothiazide is effective in doses of 12.5 to 50 mg once daily and can be given at doses of 12.5 to 25 mg as HYZAAR.

    To minimize dose-independent side effects, it is usually appropriate to begin combination therapy only after a patient has failed to achieve the desired effect with monotherapy.

    The side effects of losartan are generally rare and apparently independent of dose; those of hydrochlorothiazide are a mixture of dose-dependent (primarily hypokalemia) and dose-independent phenomena (e.g., pancreatitis), the former much more common than the latter. Therapy with any combination of losartan and hydrochlorothiazide will be associated with both sets of dose-independent side effects.

  • Other uses for this medicine

    This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

  • What special precautions should I follow?

    Before taking Hyzaar

    Losartan Potassium-Hydrochlorothiazide

    In double-blind clinical trials of various doses of losartan potassium and hydrochlorothiazide, the incidence of hypertensive patients who developed hypokalemia (serum potassium <3.5 mEq/L) was 6.7% versus 3.5% for placebo; the incidence of hyperkalemia (serum potassium >5.7 mEq/L) was 0.4%. No patient discontinued due to increases or decreases in serum potassium. The mean decrease in serum potassium in patients treated with various doses of losartan and hydrochlorothiazide was 0.123 mEq/L. In patients treated with various doses of losartan and hydrochlorothiazide, there was also a dose-related decrease in the hypokalemic response to hydrochlorothiazide as the dose of losartan was increased, as well as a dose-related decrease in serum uric acid with increasing doses of losartan.

    Hydrochlorothiazide

    Periodic determination of serum electrolytes to detect possible electrolyte imbalance should be performed at appropriate intervals.

    All patients receiving thiazide therapy should be observed for clinical signs of fluid or electrolyte imbalance: hyponatremia, hypochloremic alkalosis, and hypokalemia. Serum and urine electrolyte determinations are particularly important when the patient is vomiting excessively or receiving parenteral fluids. Warning signs or symptoms of fluid and electrolyte imbalance, irrespective of cause, include dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, confusion, seizures, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances such as nausea and vomiting.

    Hypokalemia may develop, especially with brisk diuresis, when severe cirrhosis is present, or after prolonged therapy.

    Interference with adequate oral electrolyte intake will also contribute to hypokalemia. Hypokalemia may cause cardiac arrhythmia and may also sensitize or exaggerate the response of the heart to the toxic effects of digitalis (e.g., increased ventricular irritability).

    Although any chloride deficit is generally mild and usually does not require specific treatment except under extraordinary circumstances (as in liver disease or renal disease), chloride replacement may be required in the treatment of metabolic alkalosis.

    Dilutional hyponatremia may occur in edematous patients in hot weather; appropriate therapy is water restriction, rather than administration of salt except in rare instances when the hyponatremia is life-threatening. In actual salt depletion, appropriate replacement is the therapy of choice.

    Hyperuricemia may occur or frank gout may be precipitated in certain patients receiving thiazide therapy. Because losartan decreases uric acid, losartan in combination with hydrochlorothiazide attenuates the diuretic-induced hyperuricemia.

    In diabetic patients, dosage adjustments of insulin or oral hypoglycemic agents may be required. Hyperglycemia may occur with thiazide diuretics. Thus latent diabetes mellitus may become manifest during thiazide therapy.

    The antihypertensive effects of the drug may be enhanced in the postsympathectomy patient.

    If progressive renal impairment becomes evident, consider withholding or discontinuing diuretic therapy.

    Thiazides have been shown to increase the urinary excretion of magnesium; this may result in hypomagnesemia.

    Thiazides may decrease urinary calcium excretion. Thiazides may cause intermittent and slight elevation of serum calcium in the absence of known disorders of calcium metabolism. Marked hypercalcemia may be evidence of hidden hyperparathyroidism. Thiazides should be discontinued before carrying out tests for parathyroid function.

    Increases in cholesterol and triglyceride levels may be associated with thiazide diuretic therapy.

  • What special dietary instructions should I follow?

    Talk to your doctor about what special dietary instructions you should follow

  • What should I do if I forget a dose?

    Talk to your doctor about what special instructions you should follow

  • What side effects can this medication cause?

    The most common side effects of HYZAAR in people with high blood pressure are:

    • "colds" (upper respiratory infection)
    • dizziness
    • stuffy nose
    • back pain
    • fast or irregular heartbeat (palpitations)
    • rash

    Tell your doctor if you get any side effect that bothers you or that won't go away. This is not a complete list of side effects. For a complete list, ask your doctor or pharmacist.

  • What storage conditions are needed for this medicine?

    • Store HYZAAR at room temperature at 59°F to 86°F (15°C to 30°C).
    • Keep HYZAAR in a tightly closed container, and keep HYZAAR out of the light.
  • In case of emergency/overdose

    Losartan Potassium

    Significant lethality was observed in mice and rats after oral administration of 1000 mg/kg and 2000 mg/kg, respectively, about 44 and 170 times the maximum recommended human dose on a mg/m2 basis.

    Limited data are available in regard to overdosage in humans. The most likely manifestation of overdosage would be hypotension and tachycardia; bradycardia could occur from parasympathetic (vagal) stimulation. If symptomatic hypotension should occur, supportive treatment should be instituted.

    Neither losartan nor its active metabolite can be removed by hemodialysis.

    Hydrochlorothiazide

    The oral LD50 of hydrochlorothiazide is greater than 10 g/kg in both mice and rats. The most common signs and symptoms observed are those caused by electrolyte depletion (hypokalemia, hypochloremia, hyponatremia) and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia may accentuate cardiac arrhythmias. The degree to which hydrochlorothiazide is removed by hemodialysis has not been established.

  • What other information should I know?

    Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body's response to Hyzaar.

    Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

    It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

  • Brand Names

    • Hyzaar®