Indications
Losartan, an angiotensin II receptor blocker (ARB) and hydrochlorothiazide, a diuretic indicated for:
- Treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions
- Reduction of the risk of stroke in patients with hypertension and left ventricular hypertrophy. There is evidence that this benefit does not apply to Black patients
Therapeutic Class
Pharmacology
Losartan is an angiotensin II receptor antagonist. It selectively and competitively blocks the vasoconstricting and aldosterone-secreting effects of angiotensin II by selectively antagonising its binding to AT1 receptors.
Hydrochlorothiazide inhibits the reabsorption of Na in the distal tubules causing increased excretion of Na and water including K and hydrogen ions.
Dosage & Administration
Hypertension:
- Usual starting dose: 50/12.5 mg once daily. Titrate as needed to a maximum dose of 100/25 mg.
Hypertensive Patients with Left Ventricular Hypertrophy:
- Not controlled on monotherapy: Initiate with 50/12.5 mg. Titrate as needed to a maximum of 100/25 mg.
Dosing must be individualised. 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 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. To minimise 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
Interaction
Contraindications
Side Effects
Pregnancy & Lactation
Precautions & Warnings
Use in Special Populations
Use in pediatric patients: The safety and effectiveness in paediatric patients have not been established.
Use in patients with renal impairment: The usual regimens of therapy with Losartan & Hydrochlorothiazide may be followed as long as the patient’s creatinine clearance is >30 mL/min. In patients with more severe renal impairment, loop diuretics are preferred to thiazides, so Losartan & Hydrochlorothiazide is not recommended.
Patients with hepatic impairment: Losartan & Hydrochlorothiazide is not recommended for titration in patients with hepatic impairment because the appropriate 25 mg starting dose of losartan cannot be given.
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