Losartan is FDA approved for the treatment of the several medical conditions which include the following:
Angiotensinogen is converted to angiotensin I by an enzyme, renin, that gets released from the juxtaglomerular apparatus of the kidney. Angiotensin-converting enzyme further converts angiotensin I, an inactive decapeptide, to angiotensin II, an active octapeptide. Losartan is a selective and competitive angiotensin II receptor blocker at the AT1 receptor site, resulting in a compensatory elevation of renin and angiotensin I levels. It binds with high affinity to the AT1 receptor and is more than 10000 fold selective for the AT1 receptor than the AT2 receptor. It inhibits angiotensin II-induced vasopressin release, adrenal catecholamine release, rapid and slow pressor response, thirst, cellular hypertrophy and hyperplasia, noradrenergic neurotransmission, and sympathetic tone increase. Losartan also inhibits angiotensin II-induced vasoconstriction and action of aldosterone, which in turn lowers the blood pressure. Losartan increases the urinary flow and increases the excretion of sodium, potassium, chloride, magnesium, uric acid, calcium, and phosphate. As compared to ACE inhibitors, angiotensin II-receptor blockers effectively inhibit the renin-angiotensin system, not affecting the response to bradykinin.
For this reason, the non-renin-angiotensin effects, for example, cough and angioedema, are not commonly seen with ARBs. Hepatic P450 enzyme CYP2C9 metabolizes losartan to a more potent 5-carboxylic acid metabolite, EXP 3174. The onset of action of losartan is 6 hours lasting for 24 hours, and the half-lives of losartan and EXP 3174 is 1.5 to 2 hours and 6 to 9 hours, respectively. The plasma clearance of losartan and EXP 3174 are through the kidney and liver, respectively.
Losartan administration can be without regard to meals. It is well absorbed but may be slower with food. However, it is best to administer at about the same time every day.
The primary adverse effects of losartan include hyperkalemia, renal insufficiency, and angioedema.
Greater than 10%
One percent to 10%
Frequently Not Defined
Losartan use is contraindicated with the use of aliskiren in diabetes mellitus.
It is also contraindicated in hypersensitivity to losartan or any of its components.
Losartan is contraindicated in pregnancy: As losartan acts on the renin-angiotensin system, it causes oligohydramnios, thus resulting in fetal lung hypoplasia and skeletal deformities. Potential neonatal adverse effects are skull hypoplasia, hypotension, anuria, renal failure, and death. Therefore therapy with the drug should immediately stop when pregnancy is detected.
It is not known if losartan gets excreted in the milk. Hence, its use is not recommended while breastfeeding
Monitor blood pressure, renal function (BUN and serum creatinine [SCr]), and potassium levels in patients taking losartan.
Reevaluate blood pressure (including orthostatic blood pressure), renal function, and serum potassium. Patients with systolic blood pressure <80 mm Hg, low serum sodium, diabetes mellitus, and impaired renal function should be closely monitored (ACC/AHA).
The 2017 Guideline for Management, Prevention, Detection, Evaluation of High Blood Pressure in Adults (ACC/AHA)
Confirmed hypertension along with known CVD or 10-year ASCVD risk greater than or equal to 10%: blood pressure less than 130/80 mm Hg is the recommended target. Confirmed hypertension without markers of increased ASCVD risk.
Diabetes and Hypertension
The American Diabetes Association (ADA) Guidelines
The goal of therapy for patients 18 to 65 years of age is systolic blood pressure (SBP) less than 140 mm Hg and diastolic blood pressure (DBP) less than 90 mm Hg. The goal for patients 18 to 65 years and at high risk of cardiovascular disease is SBP less than 130 mm Hg and DBP less than 80 mm Hg if this is achievable without undue treatment burden.
For patients 65 and older years who are healthy or of complex/intermediate health), the goal of therapy is SBP less than 140 mm Hg and DBP greater than 90 mm Hg.
The goal of therapy for patients 65 years of age and older and of very complex/poor health is SBP less than 150 mm Hg and DBP less than 90 mm Hg.
Any clinician (MD, DO, NP, PA) can prescribe losartan for the treatment of hypertension and diabetic nephropathy. However, clinicians should follow the patients and regularly monitor the renal function and blood pressure. The drug is effective for hypertension and can be part of long term therapy. However, it still requires the participation of an interprofessional team to optimize treatment. When initially prescribed, a pharmacist should verify appropriate dosing, perform medication reconciliation, and can counsel the patient about the drug. Nursing can also provide valuable patient counseling, as well as answer questions and assess therapeutic effectiveness on subsequent visits. If the pharmacist or nursing staff encounter any concerns, they should report these to the prescriber promptly so that therapeutic adjustments can take place. This interprofessional team approach to losartan therapy can optimize patient outcomes while minimizing potential adverse effects. [Level V]
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