Effects of glucocorticoids and idebenone on respiratory function in patients with duchenne muscular dystrophy

Pediatr Pulmonol. 2013 Sep;48(9):912-20. doi: 10.1002/ppul.22688. Epub 2012 Nov 5.


In Duchenne muscular dystrophy (DMD) progressive weakness of respiratory muscles leads to a restrictive pulmonary syndrome that contributes to early morbidity and mortality. Currently no curative treatment exists for DMD. In a Phase II randomized placebo-controlled study (DELPHI) in 21 DMD boys at age 8-16 years, idebenone (450 mg/d) showed trends of efficacy for cardiac and respiratory endpoints. Since the DELPHI study population comprised both glucocorticoid-naïve subjects and glucocorticoid-users, we now report a post-hoc analysis investigating the effects of glucocorticoids and idebenone on markers of respiratory weakness, particularly peak expiratory flow (PEF) percent predicted (PEF%p). Baseline values of PEF%p correlated well with the percent predicted values for maximal inspiratory mouth pressure (MIP%p), forced vital capacity (FVC%p), and forced expired volume in 1 sec (FEV1%p). Baseline PEF%p and FVC%p were significantly higher in patients on concomitant glucocorticoids compared to glucocorticoid-naïve patients. In the latter subgroup, idebenone caused a 8.0 ± 12.1% improvement in PEF%p, whilst patients on placebo declined by -12.3 ± 17.9% (P < 0.05) in the course of the 12 month study. In patients receiving concomitant glucocorticoids, PEF%p remained stable (-0.4 ± 14.6%) in the idebenone group compared to a decline by -6.2 ± 12.4% (P = 0.24) in the placebo group. Idebenone showed a trend for efficacy on FVC%p only in glucocorticoid-naïve patients. Because of the study limitations, these data are exploratory and preclude any firm conclusions. In conclusion, PEF appears to be a sensitive respiratory function parameter that could be a valid and clinically relevant endpoint in intervention studies in DMD. In DELPHI the effect size of idebenone on PEF%p was significantly larger in steroid-naive patients, possibly indicating a maximum treatment effect reached by steroids or steroid-mediated suppression of idebenone's effects. The impact of standard care glucocorticoids on respiratory function will have to be considered in the planning of future interventional trials in DMD.

Keywords: Duchenne muscular dystrophy; glucocorticoids; idebenone; peak expiratory flow; respiratory function.

Publication types

  • Clinical Trial, Phase II
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Antioxidants / therapeutic use
  • Child
  • Double-Blind Method
  • Glucocorticoids / therapeutic use*
  • Humans
  • Lung / drug effects
  • Lung / physiopathology
  • Male
  • Muscle Strength / drug effects
  • Muscular Dystrophy, Duchenne / drug therapy*
  • Muscular Dystrophy, Duchenne / physiopathology*
  • Respiration / drug effects*
  • Respiratory Function Tests / methods
  • Respiratory Function Tests / statistics & numerical data
  • Respiratory Muscles / drug effects
  • Ubiquinone / analogs & derivatives*
  • Ubiquinone / therapeutic use
  • Vital Capacity / drug effects


  • Antioxidants
  • Glucocorticoids
  • Ubiquinone
  • idebenone