Cozaar

Losartan and its primary metabolite block the angiotensin receptor found in many tissues, primarily in vascular smooth muscle. Angiotensin, formed by the action of angiotensin converting enzyme (ACE), is a powerful chemical that causes blood vessel narrowing (vasoconstriction) which can lead to elevated blood pressure (hypertension).

Losartan may be given with or without food. Losartan is metabolized in the liver by cytochrome P450 enzymes to an active metabolite that is responsible for most of the drug activity. Reduction in dose by 50% is suggested in patients with impaired liver function.

In studies of over 4000 patients, including 1200 treated for over 6 months and 800 for over 1 year, the overall incidence of side effects was similar to placebo. Losartan is generally well tolerated. Side effects reported included diarrhea, muscle cramps, dizziness, insomnia, and nasal congestion.

Losartan must be used with caution in patients who are volume depleted due to excessive decreases in blood pressure after use. Losartan may compromise kidney function in patients dependent on angiotensin activity to maintain kidney blood flow, similar to ACE inhibitors. This is sometimes seen in diabetic patients with some degree of kidney impairment, as well as in patients with narrowings in one of the main arteries supplying one kidney.

No significant drug interactions have been found in any studies, but inhibitors of cytochrome P450 such as ketoconazole (Nizoral) have been shown in lab studies to inhibit the formation of the active drug metabolite. Therefore, caution should be used when adding losartan to a patient taking Nizoral, as reduced activity of losartan would be expected.

Losartan's safety and efficacy in children has not been established.

Losartan is indicated for the treatment of hypertension. It may be used alone or in combination with other agents. It has less of an effect in black patients, similar to ACE inhibitors, such as captopril (Capoten), enalapril (Vasotec), and lisinopril (Zestril).

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