Prosan (Losartan Potassium): An Angiotensin II Receptor Blocker (ARB)

Prosan contains Losartan Potassium, the first non-peptide orally active angiotensin II receptor blocker. It is indicated for the treatment of hypertension and for renal protection in Type-2 diabetic patients with proteinuria. It belongs to the therapeutic class of Angiotensin-II receptor blockers.

How Prosan Works (Pharmacology)

Losartan Potassium works by:

• Blocking AT1 Receptors: It specifically binds to the AT1 receptor. These receptors are found in various tissues, including vascular smooth muscle, adrenal glands, kidneys, and the heart.
• Reducing Biological Actions of Angiotensin II: By blocking the AT1 receptor, Losartan prevents Angiotensin II (a potent vasoconstrictor) from binding and exerting its effects. This reduces several important biological actions, including vasoconstriction and the release of aldosterone.
• Lowering Blood Pressure: The reduction in vasoconstriction and aldosterone release leads to a decrease in arterial blood pressure, thereby treating hypertension.

Key Indications & Benefits

Prosan 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 diabetics who have proteinuria (defined as urinary albumin to creatinine ratio >300 mg/g).

Dosage & Administration

Prosan 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.
• Inadequate Antihypertensive Effect: If 50 mg once daily is insufficient, 25 mg twice daily is recommended before increasing the dose further.
• Patients with Intravascular Volume-Depletion: For example, those on high-dose diuretics, a starting dose of 25 mg once daily should be considered to avoid symptomatic hypotension.
• Total Daily Dose: Ranges from 25 mg to 100 mg.

Special Populations:

• Patients up to 75 years: No initial dosage adjustment is necessary.
• Patients over 75 years: A lower starting dose of 25 mg once daily is recommended due to limited clinical experience in this group.
• Patients with Renal Impairment:
  • Mild (creatinine clearance 20-50 ml/min): No initial dosage adjustment needed.
  • Moderate to severe (creatinine clearance <20 ml/min) or on dialysis: A lower starting dose of 25 mg once daily is recommended. Losartan is not significantly dialyzable.
• Patients with Hepatic Impairment: A lower dose should be considered for patients with a history of hepatic impairment, as plasma concentrations of Losartan are significantly increased in cirrhotic patients.

Important Considerations & Warnings

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

Contraindications:

• Pregnant women.
• Patients who are hypersensitive to any component of this product.
• Should not be administered with Aliskiren in patients with diabetes.

Side Effects:

• Generally mild and transient.
• Most common: Dizziness, diarrhea, nasal congestion, cough, upper respiratory infection.
• Other: Fatigue, edema, abdominal pain, chest pain, nausea, headache, pharyngitis.

Pregnancy & Lactation:

• Pregnancy Category D: The risk to the fetus increases if Losartan Potassium is administered during the second or third trimesters of pregnancy, leading to reduced fetal renal function and increased fetal and neonatal morbidity and death. Contraindicated in pregnancy.
• 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 is associated with severe fetal and neonatal risks.
• Intravascular Volume Depletion: Symptomatic hypotension may occur in patients who are intravascularly volume-depleted (e.g., those on high-dose diuretics). A lower starting dose is recommended.
• Hepatic Impairment: Plasma concentration of Prosan is significantly increased in cirrhotic patients; a lower dose should be considered.
• Renal Function Changes: Changes in renal function, including renal failure, have been reported in renally impaired patients, especially with bilateral renal artery stenosis or stenosis of the artery to a solitary kidney. These changes may be reversible upon discontinuation.
• Potassium-Sparing Diuretics: Should not be used concurrently with potassium-sparing diuretics.

Drug Interactions:

• Rifampicin and Fluconazole: Reduce levels of the active metabolite of Prosan.
• Hydrochlorothiazide: May potentiate the antihypertensive effects.
• Potassium-Sparing Diuretics (e.g., spironolactone, triamterene, amiloride), Potassium Supplements, or Salt Substitutes containing potassium: May lead to increases in serum potassium (hyperkalemia).
• Non-steroidal anti-inflammatory drug (NSAID) Indomethacin: May attenuate (reduce) the antihypertensive effect of Losartan.
• Combination of ACE-inhibitor, Angiotensin Receptor Antagonist, an Anti-inflammatory Drug, and a Thiazide Diuretic: Increases the risk of renal impairment.

Storage Conditions

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