According to lead researcher Michael A. Bolognese, MD, FACE, Bethesda Health Research, Bethesda, Maryland, United States, bisphosphonates commonly are used to prevent and treat postmenopausal osteoporosis, but must be taken over the long term to be effective, and adherence with both daily and weekly oral BPs is suboptimal. Ibandronate is a potent, nitrogen-containing BP proven to reduce the risk of fractures in women with postmenopausal osteoporosis.

MOBILE was designed as a 2-year prospective, multinational, randomized, double-blind, noninferiority study. There were 1609 women with postmenopausal osteoporosis, between the ages of 55-80 years. All women had lumbar spine (L2-L4) BMD T-scores of <-2.5 and >/=-5.0. Lumbar spine and hip (total hip, femoral neck, trochanter) BMD was measured at screening, enrollment and after 1 and 2 years.

Of the 1609 women enrolled, 402 received 2.5 mg ibandronate daily, and 401 received monthly. For the per-protocol (PP) population, there were 395 women in the 2.5-mg daily group and 396 in the 150-mg monthly ibandronate group. The baseline characteristics of the patients were well balanced across the treatment arms.

In the study, 3 monthly ibandronate doses (150-mg, 100-mg and 50+50-mg on 2 consecutive days were compared with the daily regimen of ibandronate 2.5-mg, which has proven efficacy in women with postmenopausal osteoporosis. Patients wee instructed to take the study drug in the morning (after a fast of at least 6 hours) in an upright position with 240 mL of water. After study drug intake, the patients were told to stay in an upright position and remain fasting for at least 60 minutes.

For the 2-year PP population, mean lumbar spine BMD increased relative to baseline by 3.7% in the 2.5 mg daily group and 4.8% in the 150 mg monthly group after 1 year, while the respective groups had increases of 5.0% and 6.6% after 2 years. Ibandronate 150 mg monthly was noninferior and superior to the daily dose (P <.001). After 2 years, superior mean BMD increases were seen with 150 mg ibandronate versus 2.5 mg (total hip, 4.2 vs. 2.5%; femoral neck, 3.1% vs. 19%; trochanter, 6.2%vs 4.0%).

For both doses of ibandronate, median sCTX levels were significantly suppressed at 3 months, decreasing by 53.6% with 2.5 mg daily treatment and 66.4% with 150 mg once-monthly. sCTX suppression reached steady state between 6 and 12 months and remained similar through to the 24-month assessment.

Dr. Bolognese said all regimens were generally well tolerated with a similar incidence of adverse events across all groups. The majority of adverse events were mild to moderate. Withdrawal due to GI events was low and similar in both groups (6.1% vs. 4%).

The incidence of clinical fractures was comparable across treatment arms (6.6% with 2.5 mg vs. 7.3% with 150 mg).


[Presentation title: Once Monthly Ibandronate in Postmenopausal Osteoporosis: 2-year Efficacy and Safety Data from MOBILE. Abstract 314]

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