By Liz Meszaros
PHILADELPHIA -- October 20, 2009 -- Concomitant administration of intravenous zoledronic acid 5 mg once yearly and a 20-mg daily dose of subcutaneous teriparatide (a parathyroid hormone [PTH]) seems to result in a significantly greater rise in total hip bone mineral density (BMD) than with PTH therapy alone, according to research presented here at the 2009 Annual Scientific Meeting of the American College of Rheumatology/Association of Rheumatology Health Professionals (ACR/ARHP).
Additionally, this combination therapy does not blunt the effects of PTH on lumbar spine BMD.
For this 1-year, partially double-blinded, multicentre study, 412 postmenopausal women with osteoporosis were randomised to receive either a combination of zoledronic acid and PTH, zoledronic acid alone, or PTH alone, explained Kenneth Saag, MD, MSc, University of Alabama at Birmingham (UAB) School of Medicine, and UAB School of Public Health, Birmingham, Alabama, speaking here on October 18. The mean age of these patients was 65 years. In all, 388 subjects completed the study.
At week 52, the difference in spine BMD was an increase of 7.51% in the combination arm from baseline, 7.05% in the PTH arm, and 4.37% in the zoledronic acid arm. This difference was not statistically significant when the combination therapy was compared with PTH alone, but it was statistically significant when the combination and PTH arms were compared with the zoledronic acid-alone arm (P < .001).
Combination therapy significantly increased lumbar-spine BMD at weeks 13 and 26, and total hip BMD at weeks 13, 26, and 52 when compared with PTH alone (P < .005 for all).
In the combination arm, bone turnover marker serum beta C-terminal telopeptide (beta-CTx) declined within 4 weeks, and then rose progressively thereafter to levels above baseline within 39 weeks. In this same arm, another bone turnover marker, N-terminal propeptide of type 1 collagen (P1NP), increased for up to 4 weeks, declined to a nadir at week 8, and then rose progressively to levels above baseline by week 26. Both beta-CTx and P1NP levels were lower in the combination arm versus PTH alone throughout the study (P < .002, for all).
The overall incidence of serious adverse events was 9.5% in the combination arm, 14.6% in the zoledronic arm, and 10.9% in the PTH arm. The most frequent adverse events in the combination therapy and zoledronic acid arms, compared with PTH, were transient postinfusion flu-like symptoms.
"While combination therapy and teriparatide alone produced similar effects on spine BMD, and combination therapy and zoledronic-acid therapy produced similar effects on BMD, when we consider hip and spine BMD outcomes together, the combination therapy provided the overall best BMD outcome," noted Dr. Saag. "The combination also provided the most rapid improvements in both spine and hip sites. Therefore, we might consider combination therapy in some patients at particularly high risk for fractures and osteoporosis overall."
[Presentation title: Effects of Once-Yearly Zoledronic Acid 5 mg in Combination With Teriparatide (PTH) on Postmenopausal Women With Osteoporosis. Abstract 591]
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