Cozaar (Losartan Potassium)

Cozaar (losartan potassium) belongs to a group of medications called angiotensin 2 receptor antagonists. The medicine is approved by the U.S. Food and Drug Administration (FDA) for treating hypertension,  reducing stroke risk in patients with hypertension, left ventricular hypertrophy (enlargement and thickening of the heart’s pumping chamber), and slowing kidney damage in type 2 diabetes patients who have hypertension. Cozaar also is recommended by the European Medicines Agency (EMA) for the same indications.

In scleroderma patients with Raynaud’s phenomenon, Cozaar may improve the sensations of numb, prickly, and frigid feelings in fingers and toes.

How Cozaar works

Cozaar works by blocking the activity of angiotensin 2, a molecule that is involved in the contraction of blood vessels, which leads to vessel narrowing. It performs its action by binding to so-called AT receptors, to which angiotensin 2 normally binds, subsequently preventing its effect.

In scleroderma patients with Raynaud’s phenomenon, excess collagen causes a narrowing of blood vessels. Cozaar’s vasodilating (blood vessel widening) activity is thought to counteract this vessel narrowing.

Cozaar in clinical trials

Twenty-five patients with primary Raynaud’s phenomenon and 27 patients with Raynaud’s phenomenon secondary to scleroderma participated in a randomized controlled trial that assessed the effectiveness of Cozaar and nifedipine. All patients had on average at least six episodes of Raynaud’s phenomenon per week. Of the patients with secondary Raynaud’s phenomenon, 18 had limited systemic scleroderma, and nine had diffuse systemic scleroderma.

The participants were randomized to receive either 50 mg per day of Cozaar, or 40 mg per day of nifedipine, for 12 weeks. In scleroderma patients who received Cozaar, there was a trend toward reduced episode frequency (45 percent) and severity (36 percent). However, this trend did not reach statistical significance. Nifedipine treatment had no therapeutic effects in this trial.

There was a modest but statistically significant decrease in the serum markers sVCAM-1 and PINP after Cozaar treatment, suggesting that Cozaar improved underlying pathologic processes. Both markers are elevated in scleroderma patients.

Additional information

In rare cases, Cozaar may cause a breakdown of skeletal muscles, which may lead to kidney failure. Patients should immediately inform their doctor if they have muscle pain, weakness, or tenderness in combination with unusual tiredness, dark urine, and fever.

Common side effects of Cozaar include a dry cough, muscle cramps, cold or flu symptoms, stomach pain and diarrhea, dizziness, headaches, and sleep problems.


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