Endocrine Abstracts (2008) 16 OC4.9

Teriparatide (TPTD) treatment followed by either zoledronic acid (ZOL) 5 mg once yearly or strontium ranelate (SR) 2 g daily: preliminary results from the ZOSTER-Study

Gunter Riedmüller, Astrid Fahrleitner, Harald Dobnig, Claudia Piswanger, Claudia Stiegler, Vinzenz Stepan, Barbara Obermayer-Pietsch & Dimai Hans-Peter


Medical University of Graz, Graz, Styria, Austria.


Background: TPTD treatment has been shown to reduce vertebral and non-vertebral fracture risk in postmenopausal osteoporosis efficiently. However, gains in bone mass achieved by this treatment are almost lost 2 years after cessation of treatment, unless consecutively followed by an antiresorptive treatment such as alendronate.

Subjects and methods: In the present prospective randomised open-labelled study in 52 pmp women, we investigated the effect of either 5 mg of ZOL once yearly versus 2 g of SR daily, following 18 months of TPTD treatment. Biochemical markers of bone turnover were determined before, and after 18 months of TPTD treatment. Furthermore, markers were obtained at months 3, 6, and 12 after initiation of treatment with either ZOL or SR.

Results:

Table 1 Numbers represent mean absolute values and percentual change in serum bone resorption and formation markers.
After 18 months3 months6 months12 months
TPTDZOLSRZOLSRZOLSR
OC (ng/ml) 60.216.2* (−73%)30.1 (−51%)16.8* (−72%)26.0 (−58%)18.4* (−69%)27.9 (−55%)
CTX (ng/ml) 0.570.09* (−85%)0.38 (−26%)0.15* (−77%)0.28 (−46%)0.18* (−72%)0.36 (−32%)
P1NP (ng/ml) 101.614.5* (−86%)38.6 (−62%)18.5* (−82%)31.0 (−70%)24.2* (−76%)38.4 (−63%)
TRAP (U/l) 4.52.2* (−53%)3.7 (−15%)2.5* (−47%)3.3 (−23%)2.8* (−41%)3.6 (−17%)
OC, Osteocalcin; CTX, beta CrossLaps; P1NP, type-I procollagen aminoterminal propeptide; TRAP, tartrate resistant acid phosphatase. (*P<0.05 for differences between ZOL- and SR-group; ANOVA).

Conclusion: Biochemical markers of both bone resorption and formation are significantly more suppressed after one year of treatment with a single dose of ZOL 5 mg as compared to one year of treatment with SR 2 g once daily. However, the significance of these findings on bone quality is currently unclear, since paired bone biopsies collected in this study have not yet been evaluated.