Medzart

Each film-coated tablet contains: Losartan Potassium 50 mg and 100 mg.

Pharmacology: Losartan Potassium: Angiotensin II is a potent vasoconstrictor, the primary vasoactive hormone of the renin-angiotensin system and an important component in the pathophysiology of hypertension. It also stimulates aldosterone secretion by the adrenal cortex. Losartan and its principal active metabolite block the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT₁ receptor found in many tissues. There is also an AT₂ receptor found in many tissues but is not known to be associated with cardiovascular homeostasis. In vitro binding studies indicate that losartan is a reversible, competitive inhibitor of the AT₁ receptor. The active metabolite is 10-40 times more potent by weight than losartan and appears to be a reversible, non-competitive inhibitor of the AT₁ receptor.
Neither losartan nor its active metabolite inhibits Angiotensin Converting Enzyme, nor do they bind to or block other hormone receptors or ion channels known to be important in cardiovascular regulation.
Pharmacokinetics: Losartan is readily absorbed from the gastrointestinal tract after oral doses, but undergoes substantial first-pass metabolism resulting in a systemic bioavailability of about 33%. It is metabolized to an active carboxylic acid metabolite E-3174 (EXP-3174), which has greater pharmacological activity than losartan; some inactive metabolites are also formed. Metabolism is primarily by cytochrome P450 isoenzymes CYP2C9 and CYP3A4. Peak plasma concentrations of losartan and E-3174 occur about 1 hour and 3 to 4 hours, respectively, after an oral dose. Both losartan and E-3174 are more than 98% bound to plasma proteins. Losartan is excreted in the urine, and in the faeces via bile, as unchanged drug and metabolites. About 4% of an oral dose is excreted unchanged in urine and about 6% is excreted in urine as the active metabolite. The terminal elimination half-lives of losartan and E-3174 are about 1.5 to 2.5 hours and 3 to 9 hours, respectively.

For the management of hypertension, particularly in patients who develop cough with Angiotensin Converting Enzyme (ACE) inhibitors, and to reduce the risk of stroke in patients with left ventricular hypertrophy, and in the treatment of diabetic nephropathy.

Hypertension: usual dose is 50 mg once daily may be increased, if necessary, to 100 mg daily as a single dose or in two divided doses. Or as prescribed by the physician.
Diabetic nephropathy: losartan is given in an initial dose of 50 mg once daily, increased to 100 mg once daily depending on the blood pressure. Or as prescribed by the physician.
Intravascular fluid depletion: 25 mg once daily as initial dose. Or as prescribed by the physician.

Hypersensitivity to any component of Losartan Potassium and to sulfonamide-derived drugs; anuria. Pregnancy.

Severe renal or hepatic impairment; patients w/ bilateral renal artery stenosis. Lactation.

Use in Pregnancy: When used in pregnancy during the 2nd and 3rd trimesters, drugs that act on the renin-angiotensin system (eg, losartan) can cause injury and even death to the developing fetus. When pregnancy is detected, discontinue losartan as soon as possible.

Abdominal pain, edema, asthenia, headache; palpitation; diarrhea, nausea; back pain; dizziness; dry cough, sinusitis, bronchitis, pharyngitis, upper respiratory infection. Rash.

Cimetidine, phenobarbital, rifampicin, fluconazole; potassium sparing diuretics, potassium supplements.

Store at temperatures not exceeding 30°C.

Angiotensin II Antagonists

C09CA01 - losartan ; Belongs to the class of angiotensin II receptor blockers (ARBs). Used in the treatment of cardiovascular disease.

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