How Safe Are the New COX-2 PainkillersSep 30, 2001 | Medscape
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Michael Castellino is one of approximately 33 million people who take nonsteroidal anti-inflammatory drugs (NSAIDS) like ibuprofen and diclofenac for pain (in his case, for osteoarthritis). "I can't live without my meds, but it was getting that I couldn't live with them either," says the 63-year-old New Yorker. He, like many others, began experiencing severe gastrointestinal (GI) pain and bleeding after about 6 months of regular NSAID use.
Last year the FDA approved two new anti-inflammatory drugs called COX-2 (for cyclo-oxygenase-2 inhibitors). Marketed under the names Vioxx (from Merck and Co.) and Celebrex (from Searle and Pfizer), these drugs were heralded by their makers as kinder and gentler on the stomach and kidneys than traditional NSAIDS. Several recent studies have begun to test these claims.
In a 13-month study sponsored by Searle and Co., researchers found that arthritis patients had fewer symptomatic GI ulcers and ulcer complications when taking Celebrex compared to those taking ibuprofen and diclofenac. Working with a pool of 8,000 arthritis patients, the Celecoxib Long-term Arthritis Safety Study found significant GI benefits for those taking Celebrex.
"The evidence is compelling for GI effects," says Dr. Craig Brater, dean of Indiana University School of Medicine. "No doubt, the COX-2 medications are easier on the stomach."
"We hoped that the GI protections we saw with the COX-2 medications would extend to the kidneys as well, but they didn't," says Dr. Suzanne Swan, associate professor of medicine, Division of Nephrology, Hennepin County Medical Center in Minneapolis, Minnesota. Dr. Swan is the author of a study on renal function among patients taking COX-2 medications published in the July 4, 2000, issue of the Annals of Internal Medicine. The study, supported by Merck and Co., found that patients had decreases in kidney function with Vioxx (rofecoxib) that were similar to those with the COX-1 inhibitor Indocin (indomethacin
"The biggest problems are with salt and water retention, which has worsening effects on the kidneys of people with hypertension, high blood pressure, or congestive heart failure," Dr. Swan says. "It was known that repeated use of COX-1 inhibitors like Motrin, Advil, Aleve, and the like caused kidney difficulties for this group of patients, and we found that the COX-2 inhibitor did the same."
Dr. Swan and her colleagues studied 75 patients age 60-80 with normally functioning kidneys. (Since salt intake can affect test results in renal studies, all patients were on a low-sodium diet.) Patients were divided into three groups based on what pills they were given: a COX-2 inhibitor, a COX-1 inhibitor, or a placebo. The first two groups showed similar results in decreased renal functioning.
Dr. Brater, who contributed to Dr. Swan's study, has published other studies on renal function with NSAIDS. In the December 13, 1999, issue of the American Journal of Medicine, he writes, "NSAIDS can effect renal function in a variety of ways. The most important clinical effects are decreased sodium excretion, decreased potassium excretion, and declines in renal perfusion [pumping of fluid through the kidney]." Dr. Brater told Medscape Health by Medscape, "When COX-2 were in early development, there was hope that the good effects on the stomach would also apply to the kidneys. Unfortunately, the effect on the kidneys is just like old-style medications."
According to Dr. Brater, decreased sodium excretion can result in weight gain. In severe cases renal function can decline enough to cause acute renal failure. Dr. Swan also cautions that "for many people, symptoms are not apparent until they are grave and require surgery."
If you're like Castellino, the prospect of finding pain relief without stomach irritation is a very big deal. Before taking these new medications, however, you must consult your doctor about side effects. "It's not only important for patients to consult doctors, but doctors, too, have to know about the possible renal difficulties. Too many don't, " Dr. Brater says. This is not surprising since the medications are relatively new.
Dr. Swan suggests that for "anyone who has been told to avoid long-term NSAID use, the same holds true for the COX-2 medications."
Are patients who suffer from hypertension, high blood pressure, and congestive heart failure condemned to a life of pain from their arthritis? "This is where aspirin and drugs like Tylenol come in," says Dr. Swan. "Aspirin is a gray zone that can cause stomach irritation but is not known to interfere with renal function. Most physicians feel it is safer for those at risk."
Dr. Swan suggests that when starting the COX-2 inhibitors, it is best to take low doses for a short time under close watch by a doctor. "Problems can develop in less than a week on these medications," she says, "and it is crucial to stay in touch with your doctor. Too many people get their prescription and don't see the doctor again for a long time. They can be developing serious problems without even knowing it."