Monthly- or Weekly-Dosed Bisphosphonates Equally Efficacious: Presented at ASBMR

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Title: Monthly- or Weekly-Dosed Bisphosphonates Equally Efficacious: Presented at ASBMR
URL: http://www.pslgroup.com/dg/22C212.htm
Doctor's Guide
September 15, 2008

By Louise Gagnon

MONTREAL -- September 15, 2008 -- Weekly or monthly dosing of a bisphosphonate will protect postmenopausal women with osteoporosis from sustaining a fracture, according to results of a study presented here at the American Society for Bone and Mineral Research (ASBMR) 30th Annual Meeting.

Principal investigator Steven T. Harris, MD, University of California at San Francisco, San Francisco, California, found comparable rates of fracture among patients who received either a bisphosphonate on a monthly basis or on a weekly basis.

"We contrasted the real-world experience of patients who receive weekly administration of a bisphosphonate and those who receive monthly administration," he said, speaking here at a poster session on September 14. "We looked at a huge managed-care database and claims database, and [we] looked at the fractures rates over a year."

Comparing 7,354 patients who received once-monthly ibandronate and 56,837 patients who received weekly bisphosphonates, either alendronate (35,865) or risedronate (20,972), Dr. Harris and co-investigators found the risks of hip fracture, nonvertebral fractures, and all fractures were not significantly different among patients: the rate of all fractures was 1.51% for those on weekly bisphosphonates, and 1.40% for those on monthly ibandronate (hazard ratio [HR] 0.82, P = .052).

Interestingly, the risk of vertebral fracture was lower in the ibandronate group in a statistically significant manner: 0.24% versus 0.11% (adjusted HR 0.36, P = .006).

Investigators analysed data for weekly alendronate or risedronate separately, comparing them to patients who received monthly administration of a bisphosphonate. They found the risks of hip fracture or nonvertebral fractures were similar between ibandronate and alendronate or risedronate.

"Those who were prescribed once-monthly ibandronate had about the same fracture rate as patients who received weekly risedronate or alendronate," said Dr. Harris.

There has been much debate since the introduction of bisphosphonate therapy in the management of osteoporosis about real differences in efficacy amongst agents, according to Dr. Harris, who noted that the option of weekly dosing of a bisphosphonate has been aimed at increasing adherence to drug therapy.

"The principal concern has been in the convenience of dosing," he said in an interview. "These medications have to be given in a very careful fashion. All of the bisphosphonates have to be given on an empty stomach with water."

While patients should not be encouraged to modify their therapy to monthly from weekly dosing if weekly dosing is proving efficacious, Dr. Harris said patients are attracted to the simplicity of once-monthly dosing.

"People should be assured that by switching to monthly therapy they are not trading efficacy for convenience," he said.

Patients with malignant cancer and Paget's disease were excluded from this study.

Funding for this study was provided by Roche Laboratories Inc. and GlaxoSmithKline.

[Presentation title: Fracture Risk With Once-Monthly Oral Ibandronate Compared With Weekly Bisphosphonates: Primary and Sensitivity Analyses From the Evaluation of Ibandronate Efficacy (VIBE) Database Fracture Study. Abstract Su408]

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