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9/19/2000

Rofecoxib Decreases Urinary Output in Some Elderly Patients

Kate Traynor

New research shows that rofecoxib, which is used to treat osteoarthritis symptoms and acute pain, may cause adverse kidney effects when taken by elderly patients in poor health.

Rofecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, was approved by the Food and Drug Administration in May 1999. Although COX-2 inhibitors are believed to cause fewer gastrointestinal adverse effects than traditional nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit COX-1 and COX-2, rofecoxib and similar agents have been suspected of affecting kidney function. 

A study published in the July 4 Annals of Internal Medicine (PDF) found that rofecoxib decreased renal output in elderly patients fed a low-salt diet. These findings support concerns reflected in rofecoxib's labeling, which notes that other NSAIDs reduce blood circulation in the kidney. NSAID-associated reduction in renal blood flow occurs most commonly in high-risk patients such as the elderly and those with kidney or liver disease. 

The study examined rofecoxib's effects on glomerular filtration rate, creatinine clearance, and urinary sodium and potassium levels in men and women ages 65-80. According to the authors, a report published last year showed that rofecoxib did not affect glomerular filtration rate in patients fed "sodium-replete" diets. When the authors gave rofecoxib to patients fed sodium-restricted diets, the glomerular filtration rate decreased significantly. Changes in creatinine clearance and urinary sodium and potassium levels were less pronounced. 

According to the authors, reducing dietary sodium lowers intravascular fluid levels, a condition also found in patients with congestive heart failure or liver disease. The authors caution that rofecoxib and other COX-2 inhibitors could cause renal complications in elderly patients with these and other risk factors. 

This study was funded by Merck Research Laboratories, the manufacturer of rofecoxib, or Vioxx. Nine of the 19 study authors were employed by or served as consultants to Merck.