Osartil (Losartan Potassium): An Angiotensin-II Receptor Blocker (ARB)

Osartil contains Losartan Potassium, which is the first non-peptide orally active angiotensin II receptor blocker (ARB). It is indicated for the treatment of hypertension and for renal protection in type-2 diabetic patients with proteinuria. It is classified as an Angiotensin-II receptor blocker.

How Osartil Works (Pharmacology)

Losartan Potassium exerts its antihypertensive and renal protective effects by selectively blocking the AT1 receptor:

• Angiotensin II Blockade: Losartan specifically binds to the AT1 receptor found in various tissues, including vascular smooth muscle, adrenal gland, kidneys, and the heart. Angiotensin II is a potent vasoconstrictor and a primary hormone of the Renin-Angiotensin System (RAS), stimulating aldosterone release, both of which contribute to hypertension.
• Reduced Vasoconstriction and Aldosterone Release: By blocking the AT1 receptor, Losartan reduces the key biological actions of angiotensin II, leading to vasodilation and decreased aldosterone secretion. This results in a reduction in blood pressure.

Key Indications & Benefits

Osartil is indicated for:

• Hypertension: It can be used alone or in combination with other antihypertensive agents (e.g., thiazide diuretics).
• Renal Protection in Type-2 Diabetic Patients with Proteinuria: It is indicated to delay the progression of renal disease in hypertensive type-2 diabetic patients who have proteinuria (defined as urinary albumin to creatinine ratio >300 mg/g).

Dosage & Administration

Osartil can be administered once or twice daily, with or without food. Always consult a registered physician for medication use.

• Usual starting and maintenance dose: 50 mg once daily for most patients.
• If antihypertensive effect is inadequate with 50 mg once daily: 25 mg twice daily is recommended before increasing the dose further.
• Patients with intravascular volume-depletion (e.g., on high-dose diuretics): A starting dose of 25 mg once daily should be considered.
• Total daily dose range: 25 mg to 100 mg.

Special Populations:

• Patients up to 75 years: No initial dosage adjustment is necessary.
• Patients over 75 years: Limited clinical experience; a lower starting dose of 25 mg once daily is recommended.
• Renal impairment:
  • Mild (creatinine clearance 20-50 ml/min): No initial dosage adjustment.
  • Moderate to severe (creatinine clearance <20 ml/min) or on dialysis: A lower starting dose of 25 mg once daily is recommended.
• Hepatic impairment: A lower dose should be considered for patients with a history of hepatic impairment, as plasma concentration is significantly increased in cirrhotic patients.

Important Considerations & Warnings

It is crucial to discuss your full medical history with your doctor before taking Osartil.

Contraindications:

• Pregnant women.
• Patients who are hypersensitive to any component of this product.
• Co-administration with Aliskiren in patients with diabetes.

Side Effects:

• Generally mild and transient.
• Most common: Dizziness, diarrhea, nasal congestion, cough, upper respiratory infection.
• Other: Fatigue, oedema (swelling), abdominal pain, chest pain, nausea, headache, pharyngitis (sore throat).

Pregnancy & Lactation:

• Pregnancy Category D.
• The risk to the fetus increases if Losartan Potassium is administered during the second or third trimesters of pregnancy, potentially causing fetal death. When pregnancy is detected, Osartil should be discontinued as soon as possible.
• Lactation: It is not known whether Losartan Potassium is excreted in human milk. Due to the potential for adverse effects on the nursing infant, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Precautions & Warnings:

• Pregnancy: Use during the second and third trimesters reduces fetal renal function and increases fetal and neonatal morbidity and death.
• Symptomatic Hypotension: May occur in intravascularly volume-depleted patients (e.g., those on high-dose diuretics).
• Cirrhotic Patients: Plasma concentration of Osartil is significantly increased; a lower dose should be considered.
• Renal Function Changes: Changes in renal function, including renal failure, have been reported in renally impaired patients and in patients with bilateral renal artery stenosis or stenosis of the artery to a solitary kidney (similar effects reported with other RAS-affecting drugs). These changes may be reversible upon discontinuation.
• Bilateral Renal Artery Stenosis: Other drugs affecting the renin-angiotensin-aldosterone system may increase blood urea and serum creatinine in these patients; similar effects have been reported with losartan.
• Potassium-sparing diuretics: Osartil should not be used with potassium-sparing diuretics.

Drug Interactions:

• Rifampicin and Fluconazole: Reduce levels of the active metabolite of Osartil.
• Hydrochlorothiazide: Concomitant use may potentiate antihypertensive effects.
• Potassium-sparing diuretics (e.g., spironolactone, triamterene, amiloride), potassium supplements, or salt substitutes containing potassium: May lead to increases in serum potassium.
• NSAIDs (e.g., indomethacin): The antihypertensive effect of losartan may be attenuated (reduced).
• Combination with ACE-inhibitor, angiotensin receptor antagonist, anti-inflammatory drug, and thiazide diuretic: Increases the risk of renal impairment.

Overdose Effects

• There is no specific information on overdosage in humans for Losartan Potassium.
• If overdose occurs, treatment should be symptomatic and supportive.

Storage Conditions

Keep in a dry place away from light and heat. Keep out of the reach of children.