Inhaled and systemic corticosteroid therapies: Do they contribute to inspiratory muscle weakness in asthma?
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.
Akkoca
O
O
Department of Chest Diseases, University of Ankara, Turkey.
Mungan
D
D
Karabiyikoglu
G
G
Misirligil
Z
Z
D000280:Administration, Inhalation; D000328:Adult; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000009:adverse effects*; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology; D001507:Beclomethasone / Q000008:administration & dosage / Q000009:adverse effects; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D009135:Muscular Diseases / Q000139:chemically induced*; D011241:Prednisone / Q000008:administration & dosage / Q000009:adverse effects; D012132:Respiratory Muscles / Q000187:drug effects*; D012307:Risk Factors; D013997:Time Factors
D000893:Anti-Inflammatory Agents; D001507:Beclomethasone; D011241:Prednisone