| LOSARTAN POTASSIUM
Classifications: angiotensin ii receptor antagonist; antihypertensive; Therapeutic: antihypertensive; angiotensin ii receptor antagonist
Pregnancy Category: C first trimester; D second and third trimester
25 mg, 50 mg tablet
Angiotensin II receptor (type AT1) antagonist acts as a potent vasoconstrictor and primary vasoactive hormone of the reninangiotensinaldosterone
system. Selectively blocks the binding of angiotensin II to the AT1 receptors found in many tissues (e.g., vascular smooth muscle, adrenal glands). Antihypertensive effect results from blocking
vasoconstricting and aldosterone-secreting effects of angiotensin II.
Antihypertensive effect is due to vasodilation and inhibition of aldosterone effects on sodium and water retention.
Hypersensitivity to losartan, children <6 y or children with Clcr <30 mL/min/1.73 m2; pregnancy [category C (first trimester), category D (second and third trimesters)], lactation.
Patients on diuretics, heart failure; hyperkalemia; hypovolemia; renal or hepatic impairment.
Route & Dosage
Adult: PO 2550 mg in 12 divided doses (max: 100 mg/d); start with 25 mg/d if volume depleted (i.e., on diuretics)
- Note: Starting dose is reduced 50% in patients with possible volume depletion or a history of liver disease.
Adverse Effects (≥1%)CNS:
, headache. GI:
Diarrhea, dyspepsia. Musculoskeletal:
Muscle cramps, myalgia, back or leg pain. Respiratory:
Nasal congestion, cough, upper respiratory infection, sinusitis
decreases serum levels of losartan and its metabolite.
Rapidly absorbed from GI tract; approximately 2533% reaches systemic circulation. Peak:
6 h. Duration:
24 h. Distribution:
Highly bound to plasma proteins; does not appear to cross bloodbrain barrier. Metabolism:
Extensively metabolized in liver by cytochrome P450 enzymes to an active metabolite. Elimination:
35% in urine, 60% in feces. Half-Life:
Losartan 1.52 h; metabolite 69 h.
Assessment & Drug Effects
- Monitor BP at drug trough (prior to a scheduled dose).
- Monitor drug effectiveness, especially in African-Americans when losartan is used as monotherapy.
- Inadequate response may be improved by splitting the daily dose into twice-daily dose.
- Lab tests: Monitor CBC, electrolytes, liver & kidney function with long-term therapy.
Patient & Family Education
- Notify physician of symptoms of hypotension (e.g., dizziness, fainting).
- Notify physician immediately of pregnancy.