Effects of zoledronic acid and tibolone on bone mineral density, indexes of bone metabolism, and the risk of fracture in patients with postmenopausal osteoporosis

Abstract

Objective An open study was carried out to evaluate the effect of 2 year of zoledronic acid and tibolone treatment on bone mineral density(BMD),bone remodeling markers,and the risk of fracture in women with postmenopausal osteoporosis(PMOP).Methods In total,567 PMOP women,whose ages ranged 55-64 years,were randomized to 3 groups.185 patients received infusion zoledronic acid 5 mg/year,190 patients received oral tibolone 2.5 mg/d and the rest received oral caltrate and calcitriol (control group,n =192).All of them received oral caltrate 600 mg/d and calcitriol 0.25 μg/day.BMD measurements at the lumbar spine and femoral neck by dual-energy X-ray absorptiometry (DEXA) and the biochemical markers of bone metabolism in serum were performed at the baseline and 6,12,and 24 months.Results Comparing baseline with 24 month's values,BMD increased in zoledronic acid and tibolone group,especially lumbar vertebra (L2-4,P＜ 0.01).But there was no significant deference between zoledronic acid and tibolone group (P ＞ 0.05).Zoledronic acid and tibolone resulted in a significantly greater reduction in bone-specific alkaline phosphatase (BALP),osteocalcin,tartrate-resistant acid phosphatase (TRACP5b),and collagen type Ⅰ C-end peptides (CTX) from baseline all post-baseline time (P＜0.01).There was a significant deference between zoledronic acid and tibolone group in TRACP-5b and CTX(P＜0.05).Treatment with zoledronic acid reduced the risk of new vertebral fracture by 61.9％ during a 2-year period,as compared with placebo (4.3％ in the zoledronic-acid group vs 12.6％ in the control group,P=0.033) and reduced the risk of total fracture by 65.9％ (4.3％ in the zoledronic-acid group,12.6％ in the control group,P =0.004).And in Tibolone group,incidence of total fracture were,significantly lower than in the control group (6.5％ vs 12.6％,P =0.047).There was no serious adverse event occurrence in all patientsm.Conclusions Zoledronic acid could significantly improve BMD and reduce the risk of bone fracture as tibolone.Thus it played an important role in the treatment of postmenopausal osteoporosis.There was no significant difference between these two drugs.Zoledronate can improve the compliance and safety of the patients.However,calcium tablet and vitamin D alone could not prevent the loss of bone. Key words: Zoledronic acid ; Tibolone ; Bone mineral density ; Fractures