Teriparatide and PTH 1-84 in the treatment of postmenopausal women with bisphosphonate-resistant osteoporosis: a case-control study

Osteoporosis is the most common metabolic disease of the bone, affecting especially postmenopausal women. Bisphosphonate therapy is usually the treatment of choice in osteoporotic women, but in bisphosphonate-resistant patients, drugs stimulating bone formation through osteoblast activation are needed. The aim of this study was to compare the efficacy of recombinant human PTH (PTH 1–84) and PTH 1–34 (teriparatide) in the treatment of postmenopausal osteoporotic women. Patients & Methods: A group of 58 bisphosphonate-resistant osteoporotic women were treated with recombinant PTH 1–34 (20 μg sc daily, Group 1, N=39) or PTH 1–84 (100 μg sc daily, Group 2, N=19) for 18 months. All patients underwent both pretreatment biochemical screening and BMD measurement with DXA, baseline and at the end of the study. Results: The age (76.4±5.8 vs. 75.3±6.3 years, p=0.07), BMI (27.7±2.2 vs. 26.9±2.7, p=0.23) and baseline biochemical parameters, such as serum calcium, total and bone ALP, 25(OH)vitamin D, and PTH, did not differ significantly (p= NS) between Groups (1 vs. 2), as well as lumbar spine LS-BMD (0.730±0.15 vs. 0.705±0.19 g/cm2, p=0.59) and femoral neck FN-BMD (0.597±0.08 vs. 0.590±0.09 g/cm2, p=0.76). At the end of the study, LS-BMD increased by 12.5% (t=2.20, p=0.03) and 9.4% (t=0.94, p=0.35) in Groups 1 and 2, respectively (χ2=4.93, p=0.023), while FN-BMD decreased by 3.1 % (t=0.83, p=0.41) in Group 1, and increased by 5.3 % (t=0–85, p=0.40) in Group 2. Conclusion: In women with bisphosphonate-resistant postmenopausal osteoporosis, the administration of teriparatide is useful in increasing LS-BMD, potentially reducing the risk of osteoporosis-related adverse events at this site. Both PTH 1–34 and PTH 1–84 do not change significantly FN-BMD after 36 months of treatment.