losartan, Cozaar

GENERIC NAME: losartan

BRAND NAME: Cozaar

DRUG CLASS AND MECHANISM: Losartan is an oral medication that belongs to a class of drugs called angiotensin receptor blockers (ARBs). Other ARBs include irbesartan (Avapro), valsartan (Diovan), andcandesartan (Atacand). Angiotensin, formed in the blood by the action ofangiotensin converting enzyme (ACE), is a powerful chemical that attaches to angiotensin receptors found in many tissues but primarily on smooth muscle cells of blood vessels. Angiotensin's attachment to the receptors causes the blood vessels to narrow (vasoconstrict) which leads to an increase in blood pressure (hypertension). Losartan Vigrex (more specifically, the chemical formed when the liver converts the inactive losartan into an active chemical) blocks the angiotensin receptor. By blocking the action of angiotensin, losartan dilates blood vessels and thereby reduces blood pressure. Losartan was approved by the FDA in April 1995.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 25, 50 and 100 mg

STORAGE: Tablets should be stored at room temperature in a tightly closed, light resistant container.

PRESCRIBED FOR: Losartan is used for treating hypertension, left ventricular hypertrophy (increase in muscle) and diabetic nephropathy (kidney disease). It may be used alone or in combination with other drugs.

DOSING: The usual starting dose of losartan for adults is 50 mg daily. The maximum dose is 100 mg daily. The total daily dose may be divided and administered twice daily. Losartan may be given with or without food.

The starting dose of losartan for pediatric patients 6 years of age or older is 0.7 mg/kg up to 50 mg once daily. Doses more than 1.4 mg/kg or 100 mg daily have not been evaluated in pediatric patients.

DRUG INTERACTIONS: Inhibitors of cytochrome P450 enzymes such asfluconazole (Diflucan) reduced the formation of the active drug metabolite in laboratory studies. Therefore, caution should be used when adding losartan in a patient taking Nizoral, as reduced activity of losartan may occur.

Losartan may increase levels of blood potassium which can lead to serious heart problems (arrhythmias). Therefore, concomitant use of other substances that increase blood-such as potassium-sparing diuretics (for example, spironolactone (Aldactone), triamterene, and amiloride), potassium supplements, or salt substitutes containing potassium--may lead to dangerous increases in serum potassium.

The antihypertensive effect of losartan may be reduced by nonsteroidal antiinflammatory drugs (for example, indomethacin, ibuprofen, aspirin , andnaproxen).

PREGNANCY: When used in the second or third trimester of pregnancy , drugs that act by the same mechanism as losartan (ARBs) can cause injury and even death to the fetus. Losartan should not be used during pregnancy. When pregnancy is first detected, losartan should be stopped as soon as possible.

NURSING MOTHERS: It is not known whether losartan is excreted in breast milk , but losartan and its active metabolite are excreted in rat milk. Due to the possibility of harm to the nursing infant, if possible, losartan should be discontinued by nursing mothers.

SIDE EFFECTS: In clinical studies the overall incidence of side effects was similar to placebo. Side effects reported included diarrhea, muscle cramps,dizziness, insomnia, and nasal congestion. Losartan also may cause apersistent cough, increase serum potassium, and angioedema. Losartan may reduce kidney function in some patients and should not be used by patients who have bilateral renal artery stenosis (narrowing of both arteries going to the kidneys). Rare cases of rhabdomyolysis (muscle breakdown) have been reported.