By Alan Mozes
TUESDAY, Aug. 16 (HealthDay News) -- For some gout patients afflicted with a particularly severe, crippling form of the disease who find standard treatments either intolerable or ineffective, a recently approved alternative appears to afford relief.
A new injectable treatment called pegloticase (brand name Krystexxa) has no effect on most severe gout patients, but researchers say that for the roughly four in 10 patients who do respond positively, the improvement can be significant.
Use of pegloticase was approved by the U.S. Food and Drug Administration in September 2010.
However, the treatment is expensive and the study found a high rate of side effects, some extremely serious, suggesting that health providers have to weigh the costs and benefits on a case by case basis.
"What we're focusing on here are the approximately 3 percent of gout patients who have the most advanced form of disease," said study senior author Dr. Michael A. Becker, professor emeritus of medicine at the University of Chicago.
"About 80 percent of the time these patients are intolerant of the long-standing medication for gout, allopurinol," Becker explained. "For the other 20 percent, the medication either just doesn't have sufficient efficacy or takes too long to take effect.
"So pegloticase is clearly a niche agent designed specifically for these worst cases," Becker said. "It is an expensive alternative requiring carefully monitored intravenous infusions for a prolonged period of time. And there is a potential for infusion reactions, which can be -- although usually aren't -- severe.
"But the bottom line is that this treatment offers hope for people who have been deemed otherwise not amenable to treatment with conventional agents," he concluded.
Becker and his colleagues published their findings in the Aug. 17 issue of the Journal of the American Medical Association. Savient Pharmaceuticals, which has licensed the exclusive rights to technology relating to pegloticase, funded the study and had input into it.
The study authors noted that approximately 6 million men and women in the United States suffer from some form of gout, an illness that stems from an inability of the body to adequately dispose of uric acid accumulation. Over the last two decades the number of Americans who struggle with the disease has gone up by roughly 50 percent.
For such individuals, mounting uric acid levels give rise to tiny needle-like crystal formations, which in turn lodge in joints and tissues (most notably the big toe), causing inflammation and frequently debilitating pain.
Since 1966, orally administered allopurinol (Lopurin, Zyloprim) has been the treatment of record, helping many patients by lowering the production of uric acid while draining out unsustainable deposits through the kidneys. A second oral treatment option, called febuxostat (Uloric) was approved two years ago.
But for a small minority of patients, the pills either don't work, work too slowly or prompt severe side effects. Their gout can lead to joint disease, deformity, chronic pain, disability and diminished quality of life. And for such individuals there has been no "plan B."
For some of these patients, Becker explained, bi-weekly (every two weeks) intravenous infusions of pegloticase containing a modified version of a pig enzyme called "uricase" (lacking in humans) work by quickly converting uric acid into an alternate and easily excretable fluid.
To see how effective this novel approach might be, the study authors conducted two six-month trials in tandem, involving a final total of 212 patients with severe, chronic and previously untreatable gout who were being cared for at 56 different rheumatology facilities throughout the United States, Canada and Mexico.
Patients were randomly divided into three groups: one to receive 8 milligrams of pegloticase bi-weekly; a second to receive the drug once a month; and the third placed on injectable saline (a placebo).
The result: all patients receiving pegloticase experienced a rapid drop in their uric acid levels to ranges considered normal. However, in some cases the uric acid decline was temporary, the investigators found.