Losartan

BRAND NAMES

CORAAZ: CORAAZ is available as a tablets for oral administration with 25 mg, 50 mg, and 100 mg of losartan potassium.

HYZAAR: The available dosages for HYZAAR, which combines hydrochlorothiazide and losartan, are 12.5/50 mg, 12.5/100 mg, and 25/100 mg.

MECHANISM OF ACTION:

Renin, an enzyme secreted by the juxtaglomerular apparatus of the kidney, converts angiotensinogen to angiotensin I. ACE converts angiotensin I, an active decapeptide, into angiotensin II, an active octapeptide. Losartan is a selective and competitive ARB II at the AT1 receptor, causing a compensatory increase in renin and angiotensin I levels. The medication binds strongly to the ATI receptor and is more than a thousand times more selective for the ATI receptor than the AT2 receptor.

Losartan decreases angiotensin II-induced vasopressin release, adrenal catecholamine release, quick and slow pressor responses, thirst, cellular hypertrophy and hyperplasia, noradrenergic neurotransmission, and increased sympathetic tone. Furthermore, losartan inhibits angiotensin II-induced vasoconstriction, and the effects of aldosteron, decrease blood pressure. Losartan improves urine flow and excretion of sodium, potassium, chloride, magnesium, uric acid, calcium, and phosphate.

PHARMACOKINETICS:

Absorption: Losartan is well absorbed orally while it undergoes major first-pass metabolism. The systemic bioavailability is about 33%. Losartan has an onset of action of 6 hours and lasts within 24 hours.

Distribution: Losartan has a high plasma protein binding, around 98.7% bound to plasma proteins, whereas the active metabolite E-3174 has a plasma protein binding of roughly 99.8%. Losartan's distribution volume is approximately 34 L, whereas the metabolite's is 12 L.

Metabolism: The hepatic P450 enzymes CYP2C9 and CYP3A4 convert losartan to a more powerful 5-carboxylic acid metabolite, EXP 3174.

Elimination: Losartan and active metabolite (EXP 3174) have half-lives of 1.5 to 2 hours and 6 to 9 hours, respectively. The kidney and liver are responsible for the plasma clearance of losartan and EXP 3174, respectively. Losartan and its metabolites do not accumulate in the body at therapeutic dosages.

DOSAGE AND ADMINISTRATION:

Losartan does not affect food consumption. The medicine is well absorbed; however, it takes longer with meals. However, the administration is most effective at around the same time each day. The FDA has authorized a fixed medication combination of losartan and hydrochlorothiazide. Losartan/hydrochlorothiazide combo medicine is available in three strengths: 50/12.5 mg, 100/12.5 mg, and 100/25 mg.

Adult dosage

Hypertension: The normal starting dose for losartan potassium tablets in adults is 50 mg daily. Losartan dose can be raised to a maximum of 100 mg per day. However, for individuals with low intravascular volume who are already taking diuretics, a lower beginning dosage of 25 mg is indicated. For individuals with gout and hypertension, the American College of Rheumatology recommends losartan as the preferable antihypertensive medication.

Heart failure: The indicated starting dose of losartan is 25 to 50 mg/day. The recommended daily dose is between 50 and 150 mg.

Diabetic nephropathy: Losartan's beginning dose in diabetic nephropathy is 50 mg/day. Depending on the patient's reaction, the losartan dosage may be increased to 100 mg daily.

CONTRAINDICATIONS:

• Hypersensitivity to a certain medication, class, or component.
• Caution if there is renal artery stenosis, renal impairment, or hepatic impairment.
• Caution in the event of volume depletion, hyponatremia.

DRUG INTERACTIONS:

Drugs causing hyperkalemia: Hyperkalemia can occur when losartan is used with other medications that might raise serum potassium levels. Serum potassium levels should be monitored by clinicians.

Lithium: The combined administration of lithium with ARBs, notably losartan, has been linked to higher serum lithium concentrations and toxicity. Regular monitoring of serum lithium levels is advised.

Aliskiren: Coadministration of aliskiren with losartan in diabetic individuals is not suggested. Furthermore, aliskiren with losartan should be used for people with renal impairment.

Non-steroidal anti-inflammatory drugs (NSAIDs): Co-administration of NSAIDs, especially selective COX-2 inhibitors, with ARBs such as losartan, may result in a reduction in renal function, including possible acute kidney damage in elderly patients with volume depletion, those on diuretic treatment, or persons with compromised renal function. These effects are usually reversible. Patients using losartan with NSAIDs should have their renal function monitored regularly. NSAIDs can reduce the antihypertensive effects of ARB II, which includes losartan.

SIDE EFFECTS:

Common side effects of losartan in people with hypertension include:

• Back pain
• Dizziness
• Common cold
• Nasal congestion

Common side effects of losartan in people with diabetic nephropathy include:

• Chest pain
• Diarrhea
• Hyperkalaemia
• Fatigue

Serious side effects of losartan:

• Low blood pressure
• Severe allergic reaction
• Risk of fetal harm or pregnancy loss
• Anaemia

TOXICITY:

Overdose symptoms may include hypotension, tachycardia, or bradycardia as a result of vagal stimulation. Symptomatic hypotension requires supportive therapy. Losartan and its active metabolite cannot be removed via hemolysis due to its high protein binding rates.

STORAGE CONDITIONS:

• Keep losartan at room temperature.
• Do not freeze this medicine.
• Keep this medication away from light.
• Avoid keeping this medication in wet areas.