NEW YORK (Reuters Health)—The combination of denosumab and teriparatide improves bone microarchitecture and estimated strength more than either drug alone in women with severe postmenopausal osteoporosis, researchers have found.
Dr. Joy Tsai, from Massachusetts General Hospital in Boston, and colleagues conducted a single-site, two-year, open-label, randomized controlled trial involving 94 women aged 45 or older at high risk of fractures.
They randomized patients to 24 months of 20 mcg subcutaneous teriparatide daily, 60 mcg subcutaneous denosumab every six months or both.
Total volumetric bone mineral density (BMD) at the radius and tibia, trabecular volumetric BMD at the radius, and cortical volumetric BMD at the tibia increased more in the combination group compared with both monotherapy groups (p<0.002 for all comparisons to the combination).
Total volumetric BMD at the tibia increased by 4.2% compared with 2.6% for the monotherapy groups (p=0.001). At the radius, total volumetric BMD increased 3.3% (p<0.001) compared with 3.0% in the denosumab-only group and no change in the teriparatide group.
Cortical thickness at the tibia increased 8.1% in the combination group compared with 6.0% in the denosumab group (p<0.001) and no change in the teriparatide group.
Cortical porosity at both the radius and tibia increased progressively over 24 months of treatment in those taking teriparatide, but was stable in patients in both other groups (p<0.001 teriparatide versus both other groups).
Trabecular volumetric BMD at the tibia increased similarly in all groups, whereas radius trabecular volumetric BMD increased more in those on combination treatment compared with subjects in both monotherapy groups (p<0.01 for both comparisons).
Estimated stiffness and failure load showed similar increases in all groups at the tibia. Failure load increases at the tibia were larger in the combination group (p=0.045).
Finite element analysis-estimated strength at the radius and tibia improved or was maintained by all treatments. The researchers concluded that two years of combined teriparatide and denosumab improved bone microarchitecture and estimated strength more than individual treatments, especially in cortical bone.
“This study shows that combination treatment with denosumab and teriparatide results in favorable changes in bone quality at peripheral skeletal sites,” said Dr. Tsai told Reuters Health by email.
According to Dr. Bart L. Clarke, of the Mayo Clinic in Rochester, Minnesota, these findings are important.
“What makes this work valuable,” he told Reuters Health in a phone interview, “is that we’ve had few studies on combination therapy for osteoporosis.”
Dr. Clarke, who was not involved in the research, said that the outcomes invalidate a general assumption that absorptive agents shouldn’t be used in combination with teriparatide.