Zoledronic acid improves BMD in patients with glucocorticoid-dependent DMD

Use of zoledronic acid (ZA) leads to improvement in bone mineral density (BMD) in patients with glucocorticoid-dependent Duchenne muscular dystrophy (DMD), a study has shown.

“Although the small cohort precluded demonstrable fracture benefit, improved BMD might reduce incident vertebral fracture,” the authors said.

A two-arm, parallel, randomized controlled trial was conducted in paediatric hospitals across Australia and New Zealand to examine the use of ZA in DMD in improving BMD. Sixty-two boys (31 each arm) with glucocorticoid-dependent DMD between 6 and 16 years were enrolled.

The authors then compared five ZA infusions (0.025 mg/kg at months 0 and 3, and 0.05 mg/kg at months 6, 12, and 18) plus calcium and vitamin D with calcium and vitamin D alone.

The primary endpoints were lumbar spine (LS) BMD raw and z-score by dual energy absorptiometry x-ray at 12 and 24 months, while secondary outcomes included mobility, fracture incidence, bone turnover, peripheral quantitative computerized (pQCT) and pain scores.

Mean difference in changes of LS BMD z-score in the ZA arm from baseline was 1.2 standard deviation (SD; 95 percent confidence interval [CI], 0.9–1.5) at 12 months, higher by 19.3 percent (95 percent CI, 14.6–24.0), and 1.4 SD (95 percent CI, 0.9–1.9) at 24 months, higher by 26 percent (95 percent CI, 17.4–34.5), compared with control arms (p<0.001 for both).

Five controls developed Genant 3 vertebral fractures compared with none in the ZA arm. No between-group differences were seen in mobility, pain, and bone turnover markers at 12 and 24 months. In addition, trabecular BMC and vBMD pQCT at radius and tibia were greater in the ZA vs control group at 12 months; such difference persisted at 24 months for radius but not for tibia.

“Patients with glucocorticoid-dependent DMD have increased fracture risk and reduced BMD, often precipitating mobility loss,” the authors said.