Inhaled and Systemic Corticosteroid Therapies: Do They Contribute to Inspiratory Muscle Weakness in Asthma?

• Published in: Respiration Vol. 66; no. 4; pp. 332 - 337
• Main Authors: Akkoca, O., Mungan, D., Karabiyikoglu, G., Mısırlıgil, Z.
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland Karger 1999; S. Karger AG
• Subjects: Administration, Inhalation; Adult; Anti-Inflammatory Agents - administration & dosage; Anti-Inflammatory Agents - adverse effects; Asthma - drug therapy; Asthma - physiopathology; Beclomethasone - administration & dosage; Beclomethasone - adverse effects; Biological and medical sciences; Case-Control Studies; Clinical Investigations; Drug toxicity and drugs side effects treatment; Female; Humans; Male; Medical sciences; Muscular Diseases - chemically induced; Pharmacology. Drug treatments; Prednisone - administration & dosage; Prednisone - adverse effects; Respiratory Muscles - drug effects; Risk Factors; Time Factors; Toxicity: nervous system and muscle; Respiratory muscles; Corticosteroids; Hyperinflation; Myopathy; Human; Corticosteroid; Respiratory disease; Toxicity; Systemic route; Antiasthma agent; Asthma; Inhalation; Striated muscle disease; Chemotherapy; Lung function; Treatment; Respiratory muscle; Obstructive pulmonary disease
• ISSN: 0025-7931; 1423-0356
• DOI: 10.1159/000029403

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 μg 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.