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

Abstract

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.

• Authors: Gunnar M Buyse, Nathalie Goemans, Marleen van den Hauwe, Thomas Meier
• Journal: Pediatric pulmonology (Pediatr Pulmonol) Vol. 48 Issue 9 Pg. 912-20 (Sep 2013) ISSN: 1099-0496 [Electronic] United States
• PMID: 23129412 (Publication Type: Clinical Trial, Phase II, Journal Article, Randomized Controlled Trial)
• Copyright: Copyright © 2012 Wiley Periodicals, Inc.

Chemical References

• Antioxidants
• Glucocorticoids
• Ubiquinone
• idebenone

Topics

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