Effect of Strontium Ranelate on Lumbar Spine Bone Mineral Density in Women with Established Osteoporosis Previously Treated with Teriparatide

Teriparatide (TPTD - recombinant human parathyroid hormone 1-34) markedly increases bone mineral density (BMD) and reduces fracture risk. Sequential treatment with an antiresorptive agent is believed to preserve or further increase BMD. Strontium ranelate (SR) is thought to uncouple bone remodeling resulting in increased BMD and reduced fracture risk. We aimed to evaluate the effect of SR on BMD in women with established osteoporosis previously treated with TPTD. Nineteen out of the consecutive 23 initially recruited postmenopausal Caucasian women (aged 65.9 +/- 1.8 years) with established osteoporosis completed treatment with TPTD, 20 mu g daily for 18 months, followed by SR 2g daily for 12 months. Lumbar spine BMD was measured by dual-energy X-ray absorptiometry (DXA) pre- and post-TPTD administration, as well as twelve months post-SR administration. Blood samples for bone-specific alkaline phosphatase (BSAP) and C-terminal telopeptide of type I collagen (CTx) were obtained at the same time points. Lumbar spine BMD increased significantly after 18 months of TPTD (p<0.001) and further improved with sequential SR treatment (p=0.033). Serum BSAP and CTx increased significantly with TPTD (p=0.008 and 0.017, respectively) and reduced to baseline levels after SR treatment (p=0.031 and 0.019, respectively). The change in BSAP was positively correlated with the change in CTx during both TPTD (r=0.641, p=0.007) and SIR treatment (r=0.539, p=0.026). In conclusion, our data suggest that SR following TPTD administration further increases BMD and Could represent an effective sequential treatment.