Bisphosphonate shows efficacy on intermittent regimen. (Schedule Called 'Impractical').
Treatment with ibandronate, a new bisphosphonate that is now under marketing review by the Food and Drug Administration for the treatment of osteoporosis with a daily dosing regimen, led to a significant drop in fractures in a controlled 3-year study of almost 3,000 women. With the intermittent-dosage regimen, women took the drug every other day for 24 days, followed by a treatment hiatus of about 66 days before they repeated the regimen cycle, Dr. Robert R. Recker reported at the annual meeting of the American Society for Bone and Mineral Research.
"This is the first real demonstration of the efficacy of an intermittent regimen with a bisphosphonate," commented Dr. Socrates E. Papapoulos, professor of endocrinology at Leiden (the Netherlands) University
Last February, an international team of researchers published a report that an intravenous dose of the bisphosphonate zoledronic acid, given once every 3 months, led to improvements in bone mineral density (N. Engl. J. Med. 346:653-61, 2002). The new report is the first to test intermittent dosing using the benchmark measure of efficacy, a decrease in fracture incidence.
But the awkward ibandronate regimen used in the new study is unlikely to be readily adopted into clinical practice.
"The dosing schedule is too complicated and impractical. An intermittent regimen makes sense, but not one where patients always need to check a calendar," commented Dr. Michael McClung, director of the Oregon Osteoporosis Center in Portland.
According to a spokesman for Roche, one of the two companies that makes ibandronate and sponsored the new study, FDA approval for the intermittent regimen tested in the study is not being sought because it is "complex and not ideal for patients." However, Roche and GlaxoSmithKline, which are partnering in this endeavor, will investigate the efficacy of other intermittent regimens, such as a monthly dosing scheme.
"Once an intermittent dosing regimen shows efficacy for preventing fractures, it opens the door for finding other intermittent regimens," Dr. Recker told this newspaper. The results "validate an intermittent schedule for ibandronate and other bisphosphonates," said Dr. Recker, director of the osteoporosis research center at Creighton University in Omaha, Neb. The unusual regimen tested in the study was devised empirically based on the results from preliminary studies.
The study enrolled postmenopausal women, aged 55-80 years, at 73 medical centers. Their mean age was 69 years. All of the women had been diagnosed with osteoporosis.
After randomization, 977 women received 2.5 mg of ibandronate daily 977 women received 20 mg of ibandronate every day that they took the drug on the intermittent schedule, and 975 women were controls and received a daily placebo. Ibandronate was taken on rising in the morning followed by exclusion of all food and drink, except water, for 1 hour.
After 3 years of treatment, the incidence of new vertebral fractures was 9.6% in the control group, 4.9% among the women on intermittent ibandronate, and 4.7% among those on daily ibandronate. The reductions in the drug-treated groups were statistically significant compared with the control group, but there was no statistically significant difference between the daily and intermittent groups. Both of the ibandronate regimens were well tolerated.
In a separate report at the meeting, a daily dose of 2.5 mg of ibandronate boosted bone mineral density compared with placebo during 2 years of treatment in postmenopausal women who did not have osteoporosis on entry, reported Dr. McClung. The study involved slightly more than 600 participants, and it also tested two smaller daily doses of ibandronate, which were not as effective as the 2.5-mg dose.
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|Publication:||OB GYN News|
|Date:||Dec 1, 2002|
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