IOF World Congress on Osteoporosis

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MAY 13, 2002

Lisboa Congress Center, Portugal

New dosing schedules explored in continued attempt to improve tolerability of osteoporosis therapeutics

Bisphosphonates, a widely used class of chemical compounds that are used in the first-line treatment of osteoporosis and have demonstrated efficacy in preventing bone resorption and increasing bone mineral density (BMD), are nonetheless hindered by gastrointestinal toxicity that limits their use in some patients due to the current daily dosing schedule. Thus the potential for less frequent dosing has been the subject of several clinical trials in recent years. However, this alternative is only valid if the studies succeed in demonstrating that therapeutic efficacy can be maintained while side effects are reduced with less frequent dosing.

The results of a randomized, double-blind study enrolling 1,456 postmenopausal osteoporotic women with low lumbar spine BMD and history of at least one vertebral fracture were presented Saturday at the IOF World Congress on Osteoporosis. The positive results described by lead investigator Dr. Jonathan Adachi of McMaster University, Ontario, Canada demonstrate that a single once-weekly oral dose of risedronate (35 mg) is as effective as once-daily risedronate (5 mg) in increasing lumbar spine, total hip, femoral neck and trochanteric BMD after one year of drug therapy. Significant increases in lumbar spine BMD T-score as compared to baseline were observed in all risedronate-treated women, with increases of 3.94% and 4.0% in the 35 mg once-weekly and the 5 mg once-daily treatment groups.

Furthermore, a larger dose of 50 mg once weekly was not statistically more effective than the 35-mg dose: lumbar spine BMD increased by 4.25% in women receiving this dose. Most importantly, tolerability of the once-weekly dose was reported to be extremely good, supporting the validity of once-weekly dosing as an alternative to once-daily risedronate.

"Risedronate does at 35 mg once weekly is therapeutically equivalent to 5 mg/day in the treatment of postmenopausal osteoporosis." The key to effective treatment is patient compliance. "When we're looking at a young, busy working person, for example, the most important factor is convenience. More people are willing to take it and fewer people are coming off the drug," Adachi said.

The International Osteoporosis Foundation (IOF) is a worldwide organization dedicated to the fight against osteoporosis around the world. It brings together scientists, physicians, patient societies and corporate partners. Working hand in hand with its 139 member societies in 71 countries and other healthcare-related organizations around the world, IOF encourages awareness and prevention, early detection and improved treatment of osteoporosis.

The IOF World Congress on Osteoporosis is being held May 10-14, 2002 in Lisbon, Portugal. Some 5,000 participants are expected for the congress, expected to be the largest gathering ever of osteoporosis specialists from around the world. Abstracts from the congress are published in a supplementary volume of the journal Osteoporosis International. For more information visit the congress website:

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