The rhPTH (1-34), But not Elcatonin, Increases Bone Anabolic Efficacy in Postmenopausal Women with Osteoporosis

Purpose: Intermittent administration of recombinant human PTH [rhPTH (1-34)] exerts an osteoanabolic effect characterized by direct effects on bone formation, increases bone density, and reduces fracture risk. This study was to investigate the anabolic effects of rhPTH(1-34) on postmenopausal osteoporosis in an Asian population and compare the time course and alteration in bone turnover marker (BTM) during rhPTH(1-34) and elcatonin treatment. Methods: 124 women with postmenopausal osteoporosis were enrolled in this prospective, open-label, active-controlled trial. The patients randomized to subcutaneous rhPTH(1-34) (20 ug, once daily) or elcatonin (200U, once week) injections for 12 months. Biochemical markers of bone formation (bone specific alkaline phosphatase [BSAP]), and bone resorption maker (serum C-telopeptide of type I collagen [CTX-1] were measured at baseline and at 0, 6, and 12 months. Results: At 12 months, rhPTH (1-34) significantly increased lumbar spine BMD significantly compared with baseline, whereas elcatonin was ineffective. BSAP levels were gradually increased in almost all rhPTH(1-34)-treated subjects and at the end of the study, the percentage of subjects with BSAP above the postmenopausal reference interval was gradually increased as high as 91.5% at month 12. Opposite trends in percentages for CTX-I was observed in rhPTH(1-34). With rhPTH(1-34), but not elcatonin, there were significant positive correlations between ratio of BSAP and CTX-I and bone mineral density (BMD) (r = 0.318) at the end of month 12. Both treatments were well tolerated and there were no significant differences detected between the 2 groups in the proportion of any adverse events and any serious adverse events. Conclusions: rhPTH (1-34) has more positive effects on bone formation than elcatonin for postmenopausal women with osteoporosis and was proved to be safe and well tolerated. The ratio of BSAP and CTX-I may be a useful indicator for positive bone formation.