RISEDRONATE REDUCES INCIDENCE OF GASTRIC ULCERS.

Data from a McMaster University, Toronto, Ontario, endoscopy study published recently in Gastroenterology and presented at the annual meeting of the American Society for Bone and Mineral Research (ASBMR) showed that risedronate sodium (Actonel) reduced the incidence of gastric ulcers in healthy, postmenopausal women relative to another osteoporosis therapy, alendronate sodium. Research demonstrated that gastric ulcers developed in three times as many participants treated with alendronate as those treated with risedronate.

In a second study presented at ASBMR, risedronate was as well-tolerated as placebo in women who had previously discontinued alendronate therapy due to upper gastrointestinal (GI) adverse events. In a study published in the Journal of Managed Care Pharmacy, discontinuation of alendronate therapy within the first six months of treatment occurred in 35 percent of patients, most often because of gastrointestinal complaints (51.9 percent).

"An osteoporosis medication -- long-term or otherwise -- can work only if a patient can tolerate the medication. It will be exciting to see how the results of endoscopy studies translate to differences in event rates and tolerability in clinical practice," said Dr. John Marshall, Assistant Professor, Division of Gastroenterology, McMaster University, Hamilton, Ontario, Canada.

About the Endoscopy Study

In the study presented by Dr. Marshall, gastric ulcers occurred in 69 percent fewer study participants treated with risedronate compared to those treated with alendronate (4.1 percent vs. 13.2 percent, respectively; p<0.001). The two-week, clinical study enrolled 515 healthy, postmenopausal women who received 5 mg of risedronate or 10 mg of alendronate for the duration of the study. These women were required to abstain from medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), and activities, such as smoking, that have the potential to irritate the GI mucosa.

Gastric ulcer incidence is a recognized outcome measure in comparative endoscopy studies evaluating medications known to irritate the gastric mucosa. Gastric ulcers are important because they can be associated with clinically relevant complications such as gastric bleeding or perforations. The other key study criteria, including use of endoscopic evaluation rather than symptomatology and study duration, also have been commonly used in studies of cyclooxygenase-2 (COX-2) and NSAIDs.

Tolerability is a critical attribute when considering an osteoporosis medication. In fact, a favorable drug safety profile was cited as the most important characteristic of an osteoporosis medication by 93 percent of physicians surveyed recently at the World Congress on Osteoporosis. "Endoscopy studies are one important measure of tolerability and safety. The combination of efficacy, tolerability and other safety parameters provides us with the best means of evaluating these agents," Dr. Marshall said.

Currently, there are no head-to-head data comparing the efficacy, overall safety, and tolerability of risedronate and alendronate in the treatment of postmenopausal or glucocorticoid-induced osteoporosis. Long-term studies comparing the incidence of serious, clinically-significant upper GI adverse events in patients taking risedronate versus alendronate have not been performed. The correlation between endoscopic findings and the relative incidence of clinically-serious upper GI events that may be observed with different products has not fully been established.

About the Discontinuation Study

A second study presented by Dr. Rick Adachi, professor, Department of Medicine, McMaster University and St. Joseph's Hospital evaluated 66 postmenopausal, osteoporotic women who had previously discontinued therapy with alendronate due to upper GI complications within the first three months of treatment. This three-month, randomized, double-blind, placebo-controlled trial assessing the ability of these patients to continue treatment when taking risedronate found that 89 percent of the women were able to tolerate risedronate. Discontinuation rates due to upper GI adverse events were 11 percent for risedronate and 16 percent for placebo; overall, adverse events were comparable to placebo. The study included patients with a history of H2-blocker/proton pump-inhibitor use, who often experience GI complications when undergoing bisphosphonate therapy.

"Tolerability during the first few months of therapy is a key marker for patient satisfaction and compliance," said Dr. Adachi. "The favorable tolerability of risedronate in this study is encouraging. It suggests that intolerance due to GI adverse events with one bisphosphonate does not preclude use with another bisphosphonate."

The Importance of Safety

Clinical data for risedronate show that it can provide effective treatment and have a good tolerability profile. This is essential to managing this devastating disease.

"There is a great need for osteoporosis treatments that work to prevent and treat osteoporotic fractures, and do so with a good tolerability profile," said Dr. Adachi. "A medication associated with a low incidence of gastric ulcers can help patients stick with their treatment regimen and help optimize their chances for successful treatment. The data on risedronate suggest that it offers this benefit."

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