Reverse sequence doesn't work: sequential PTH, alendronate shows synergistic effect.(Gynecology)

SNOWMASS, COLO. -- Sequential use of recombinant parathyroid hormone followed by an antiresorptive agent is a promising therapeutic strategy in osteoporotic patients at high risk of fractures, Dr. Kenneth G. Saag said at a symposium sponsored by the American College of Rheumatology.

The same can't be said for the reverse sequence. Several trials have demonstrated in both osteoporotic men and women that sequential therapy with alendronate first, followed by parathyroid hormone (PTH), seems to attenuate PTH's ability to increase bone mineral density (BMD) at the spine and femoral neck. Concurrent therapy with PTH and alendronate has shown no advantage over PTH alone in terms of increased BMD.

"We were hoping we could use these drugs synergistically and see a benefit," noted Dr. Saag, director of the center for education and research on therapeutics of musculoskeletal disorders at the University of Alabama, Birmingham.

A downside of PTH therapy is that the dramatic improvements in BMD dissipate rapidly in the first year after daily injections are stopped. But Canadian investigators have shown in a study of 66 patients with postmenopausal osteoporosis that a year of PTH followed by a year of alendronate not only prevents the early post-PTH loss of BMD, but actually induces further gain.

The net effect of the ...