Losartan, the first of a new class of antihypertensives, is a specific and selective antagonist of angiotensin II at the AT1 sites. Angitensin II is a potent vasoconstrictor, the primary vasoactive hormone of the renin-angiotensin system and an important component in the pathophysiology of hypertension. Losartan and its principal active metabolite block the vasoconstriction and aldosterone secreting effects of angiotensin II to the AT1 receptor found in many tissues. Losartan is now regarded as the first-line therapy option for treating high blood pressue.
Losartan is an angiotensin II receptor blocker (ARB) used for:
- Treatment of hypertension, to lower blood pressure in adults and children greater than 6 years old. 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.
- Treatment of diabetic nephropathy with an elevated serum creatinine and proteinuria in patients with type 2 diabetes and a history of hypertension.
|Therapeutic Class||Angiotensin-ll receptor blocker|
|Manufacturer||Concord Pharmaceuticals Ltd|
|Last Updated:||June 23, 2021 at 11:22 am|
Table Of contents
- Usual adult dose: 50 mg once daily.
- Usual pediatric starting dose: 0.7 mg per kg once daily (up to 50 mg).
Hypertensive Patients with Left Ventricular Hypertrophy:
- Usual starting dose: 50 mg once daily.
- Add hydrochlorothiazide 12.5 mg and/or increase Losartan to 100 mg followed by an increase to hydrochlorothiazide 25 mg if further blood pressure response is needed.
Nephropathy in Type 2 Diabetic Patients:
- Usual dose: 50 mg once daily.
- Increase dose to 100 mg once daily if further blood pressure response is needed.
Use in elderly:
- Patients up to 75 years: No initial dosage adjustment is necessary for this group of patients.
- Patients over 75 years: A lower starting dose of 25 mg once daily is recommended.
In controlled clinical trials in patients with essential hypertension, dizziness was the only side effect reported that occurred with an incidence greater than placebo in 1% or more of patients treated with Losartan. Rarely, rash was reported although the incidence in controlled clinical trials was less than placebo. Angioedema, involving swelling of the face, lips and/or tongue has been reported rarely in patients treated with Losartan. Serious hypotension (particularly on initiating treatment in salt-depleted patients) or renal failure (mainly in patients with renal artery stenosis) may be encountered during Losartan treatment.
A lower dose should be considered for patients with a history of hepatic and renal impairment. Losartan should not be used with potassium-sparing diuretic
No drug interaction of clinical significance has been identified. Compounds which have been studied in clinical pharmacokinetic trials include hydrochlorothiazide, digoxin, warfarin, cimetidine, ketoconazole and phenobarbital.
Pregnancy & Breastfeeding use
Although there is no experience with the use of Losartan in pregnant women, animal studies with Losartan potassium have demonstrated fetal and neonatal injury and death, the mechanism of which is believed to be pharmacologically mediated through effects on the renin angiotensinaldosterone system. Losartan should not be used in pregnancy and if pregnancy is detected Losartan should be discontinued as soon as possible.
It is not known whether Losartan is excreted in human breast milk. However, significant level of Losartan found in rat milk which suggests that the drug should not be used in lactating mother.
It is also contraindicated to patients who are hypersensitive to any component of this product. In patients who are intravenously volume depleted (e.g. those treated with high dose diuretics), symptomatic hypotension may occur. These conditions Losartan potassium should be corrected prior to administer Losartan or a lower starting dose (usually 25 mg) should be used.
No initial dosage adjustment is necessary in patients with mild renal impairment (CrCl 20-50 ml/min). For patients with moderate to severe renal impairment (CrCl <20 ml/min) or patients on dialysis, a lower starting dose of 25 mg is recommended.
Limited data are available regarding overdose in humans. The most likely manifestation of overdose would be hypotension and tachycardia; bradycardia could occur from parasympathetic (vagal) stimulation. Supportive treatment should include repletion of the intravascular volume. Neither Losartan nor the active metabolite can be removed by hemodialysis.
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