Six months of parathyroid Hormone (1-84) administered concurrently versus sequentially with monthly ibandronate over...

PTH therapy improves bone mineral density (BMD) and decreases fractures in postmenopausal osteoporosis, but cost and the burden of daily injections limit its use.

We evaluated two novel approaches to the use of 6 months of PTH therapy over 2 yr.

We conducted a randomized, double-blinded trial of two combinations of daily PTH(1-84) and monthly ibandronate in 44 postmenopausal women with low bone mass. Participants received either 6 months of concurrent PTH and ibandronate, followed by 18 months of ibandronate (concurrent) or two sequential courses of 3 months of PTH followed by 9 months of ibandronate (sequential) over 2 yr.

Bone turnover markers were measured. Areal and volumetric BMD were assessed by dual-energy x-ray absorptiometry and quantitative computed tomography, respectively.

Over 2 yr, areal BMD at the spine and hip increased similarly in both groups, with 7.5 and 8.2% increases in spine BMD in the concurrent and sequential arms, respectively (difference -0.6%, 95% confidence interval=-3.4-2.1%). Volumetric BMD also increased similarly between groups. With concurrent therapy, mean N-propeptide of type I collagen increased 75% between baseline and month 1 and then declined. With sequential therapy, the second 3-month PTH course increased N-propeptide of type I collagen markedly (209%), although to a lesser absolute degree than the first.

Six months of PTH(1-84), used over 2 yr with a bisphosphonate in either of our dosing regimens increased BMD substantially. Short PTH courses may provide the benefits of anabolic osteoporosis therapy with reduced burden for patients.