PHILADELPHIA — Once-monthly oral ibandronate (Boniva) increases spine and hip bone mineral density beyond 2 years, Dr. Paul D. Miller reported in a poster presented at the annual meeting of the American Society for Bone and Mineral Research.
Dr. Miller, of the department of medicine at the University of Colorado, Denver, and medical director of the Colorado Center for Bone Research, Lakewood, and his colleagues presented 1-year results from the long-term extension phase of the MOBILE (Monthly Oral Ibandronate in Ladies) study. In year 3 of treatment with oral ibandronate, lumbar spine bone mineral density (BMD) increased 1.5% for women receiving 150 mg once monthly and 1.1% for women receiving 100 mg once monthly. In the same period, total hip BMD increased 0.3% in the 150-mg group; total hip BMD did not change for the 100-mg group.
In the MOBILE study, 1,609 postmenopausal women with osteoporosis were randomized to receive 100 mg (single dose), 50 mg plus 50 mg (50-mg doses on 2 consecutive days), or 150 mg (single dose) of monthly oral ibandronate, or 2.5 mg of oral daily ibandronate.
At 2 years, once-monthly oral ibandronate provided superior increases in lumbar spine BMD compared with the daily regimen (Ann. Rheum. Dis. 2006;65:654–61). In 2005, the Food and Drug Administration approved the 150-mg, once-monthly dosage of oral ibandronate.
After 2 years, the MOBILE study was extended for another 3 years. In the extension phase, patients in the 100-mg (single dose) or 150-mg oral ibandronate once-monthly groups maintained these regimens. Patients who were originally randomized to daily treatment or the 50 mg plus 50 mg (50-mg doses on 2 consecutive days) per month regimens were rerandomized to receive either 100 mg once monthly or 150 mg once monthly.
All patients received daily calcium (500 mg) and vitamin D (400 IU) supplements.
For 168 women on 150-mg once-monthly oral ibandronate for 3 years (the 2 years of the MOBILE study and 1 year of the extension study), lumbar spine BMD increased 7.6% from baseline.
Likewise, for 173 women on 100 mg ibandronate, lumbar spine BMD increased 6.4% from baseline. Also, total hip BMD increased 4.1% from baseline in women in the 150-mg group, while it increased 3.4% from baseline in the 100-mg group. Over 3 years, there were also gains of 2.5% and 3.5% from baseline at the femoral neck for the 100-mg and 150-mg groups, respectively. In the same period, there were gains of 5.4% and 6.2% from baseline at the trochanter for the 100-mg and 150-mg groups. The long-term extension study was funded by F. Hoffmann-LaRoche Ltd. and GlaxoSmithKline Inc. Dr. Miller reported receiving funding and consulting fees from both companies.
In a separate poster, Dr. Stuart Silverman, a rheumatologist at Cedars-Sinai Medical Center in Los Angeles, and his colleagues reported on adverse events from the MOBILE study.
A total of 719 women—359 in the 100-mg group and 360 in the 150-mg group—were included in the safety analysis.
The rates of drug-related adverse events were generally low and comparable for the two groups (7.8% for the 100-mg group and 7.5% for the 150-mg group). Only one serious adverse event was considered to be possibly related to treatment with 150-mg oral ibandronate once monthly.
The rates of drug-related adverse events leading to withdrawal were also comparable between the two groups (0.3% in the 100-mg group and 0.8% in the 150-mg group).
Gastrointestinal events have often been cited by patients as a reason for discontinuing oral bisphosphonates. The incidence of upper-GI adverse events was 4.5% and 6.9% in the 100-mg and 150-mg groups, respectively. No serious upper-GI adverse events occurred. The five most common upper-GI adverse events reported were dyspepsia, nausea, upper-abdominal pain, gastritis, and vomiting.
Dr. Silverman reported receiving funding from F. Hoffmann-LaRoche Ltd. and GlaxoSmithKline.