Inhaled and systemic corticosteroid therapies: Do they contribute to inspiratory muscle weakness in asthma?

Respiration. 1999;66(4):332-7. doi: 10.1159/000029403.

Abstract

Background: Patients with asthma incur the risk of steroid-induced myopathy, which is a well-known side effect of treatment with corticosteroids. However, the adverse effect of long-term steroid treatment on respiratory muscle function remains controversial.

Objective: We aimed to evaluate the effects of long-term moderate dose of systemic corticosteroids and high-dose inhaled beclomethasone on maximal inspiratory and expiratory pressures (PImax and PEmax, respectively) in two groups of asthmatic patients exhibiting comparable levels of hyperinflation.

Methods: Twelve steroid-dependent asthmatic patients requiring 10-20 mg/day of prednisone-equivalent corticosteroids for an average of 9.83 +/- (SD) 9.86 years; 14 subjects with moderate to severe asthma who have used inhaled beclomethasone for at least 1 year at a daily dose higher than 1,000 microg and 15 healthy controls were included to the study.

Results: No significant difference in pulmonary function tests and arterial blood gases appeared between two asthmatic groups with different treatment modalities. PImax as an absolute value was significantly lower in steroid-dependent asthmatics than in patients treated with inhaled beclomethasone and controls (p < 0.01). %PImax was also lower in steroid-dependent asthmatics than in control groups (p < 0.01). A significant correlation was found between %PImax and hyperinflation assessed by %RV, %FRC, %FRC/TLC (p < 0.05) in all asthmatic patients.

Conclusions: We believe that hyperinflation plays a major role in inspiratory muscle dysfunction in asthma, but the finding of significantly decreased PImax values in steroid-dependent asthmatics when compared with patients on high-dose inhaled beclomethasone with a comparable level of hyperinflation points to a deleterious effect of long-term, moderate-dose systemic corticosteroid but not high-dose beclomethasone on inspiratory muscle function in asthmatics.

MeSH terms

  • Administration, Inhalation
  • Adult
  • Anti-Inflammatory Agents / administration & dosage
  • Anti-Inflammatory Agents / adverse effects*
  • Asthma / drug therapy*
  • Asthma / physiopathology
  • Beclomethasone / administration & dosage
  • Beclomethasone / adverse effects
  • Case-Control Studies
  • Female
  • Humans
  • Male
  • Muscular Diseases / chemically induced*
  • Prednisone / administration & dosage
  • Prednisone / adverse effects
  • Respiratory Muscles / drug effects*
  • Risk Factors
  • Time Factors

Substances

  • Anti-Inflammatory Agents
  • Beclomethasone
  • Prednisone