BOSTON — Intermittent intravenous ibandronate is at least as effective as daily oral ibandronate for increasing bone mineral density and may be preferable to oral dosing in patients with esophageal disease or compliance problems.
There are no fracture data for the intravenous dosing schedule, but the risk reduction that has been shown with oral ibandronate can probably be extrapolated to the intravenous form of the drug, Dr. Mone Zaidi said at the annual meeting of the Endocrine Society.
Oral ibandronate has been shown to reduce the risk of new vertebral fractures by up to 60% (Curr. Med. Res. Opin. 2005;21:391–401; J. Bone Miner. Res. 2004;19:1241–9). “If you can show equivalence or superiority in bone mineral density changes to [the form] with proven fracture data, which we have done, I think everyone would agree that you can extrapolate that data,” said Dr. Zaidi, director of the Mount Sinai Bone Program, Mount Sinai School of Medicine, New York.
Dr. Zaidi presented 2-year bone mineral density (BMD) data from the ibandronate Dosing Intravenous Administration trial, a Roche-sponsored phase III study that compared two doses of intravenous ibandronate (2 mg every 2 months and 3 mg every 3 months) with the approved oral dosing schedule (2.5 mg daily). The study group included 1,400 postmenopausal women with low bone mass (T scores of −3.3 for total spine and −2 for hip).
After 2 years, BMD at the lumbar spine increased significantly more in both intravenous groups than in the oral group (mean increase 6.4% for the 2-mg IV dose, 6.3% for the 3-mg IV dose, and 4.8% for the oral dose). BMD increased similarly at all other sites measured, with consistently greater gains in both intravenous groups than in the oral group, Dr. Zaidi said.
At 2 years, the incidence of adverse events was similar across all groups. There was no osteonecrosis of the jaw. Renal and urinary incidents were uncommon and similar across groups.
Fracture incidence, which was reported as an adverse event, was low and similar in all groups, although Dr. Zaidi stressed that the study was not powered to prove fracture risk reduction.