Mucociliary clearance in patients with chronic asthma: effects of beta agonists.
OBJECTIVE
Chronic asthma is characterized by airway inflammation, mucus hypersecretion and impaired mucociliary clearance (MCC). We investigated baseline MCC and the acute effect of terbutaline in chronic asthmatics with sputum production while on long-term treatment with salmeterol in combination with inhaled corticosteroids (ICS).


METHODS
MCC was measured at baseline and in response to 1 mg terbutaline (or placebo) on three visits over 80 min in 16 asthmatics (52+/-13 years of age). Subjects who had greater than 10% absolute increase in MCC above baseline and placebo, after terbutaline, were categorized in group A and subjects who had less than 10% in group B.


RESULTS
In group A subjects (n=6), MCC increased from 23.7+/-4.0% at baseline to 43.7+/-4.9% with terbutaline (P<0.0001) and to 34.4+/-5.7% with placebo (P<0.01). In group B subjects (n=10), MCC remained similar: 11.3+/-3.2% at initial baseline, 12.0+/-3.2% with terbutaline and 7.3+/-3.0% with placebo (P>0.05). Group B subjects withdrew from all beta(2) agonists for a week and MCC was remeasured. After withdrawal, baseline MCC (7.0+/-1.8%) was similar to the initial baseline value (P>0.1) and MCC with terbutaline (15.8+/-4.9%) was greater than baseline (P<0.005) but remained abnormal in most subjects. Baseline percentage predicted FEV(1) and FEF(25--75%) were 77.3+/-7.2 and 41.7+/-5.6 in group A and 59.9+/-8.1 and 29.5+/-8.4 in group B subjects, respectively.


CONCLUSIONS
MCC was impaired in most of these asthmatics with persistent airway obstruction and sputum production, despite regular treatment with ICS and salmeterol. In addition, there was little or no stimulation of MCC acutely after terbutaline in most of these asthmatics.
Daviskas
Evangelia
E
Department of Respiratory Medicine, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia.
Anderson
Sandra D
SD
Shaw
Janet
J
Eberl
Stefan
S
Seale
J Paul
JP
Yang
Ian A
IA
Young
Iven H
IH
D000280:Administration, Inhalation; D000293:Adolescent; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage*; D000328:Adult; D000368:Aged; D001249:Asthma / Q000000981:diagnostic imaging / Q000235:genetics / Q000503:physiopathology*; D002908:Chronic Disease; D004334:Drug Administration Schedule; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009079:Mucociliary Clearance / Q000187:drug effects*; D011859:Radiography; D013147:Spirometry; D013726:Terbutaline / Q000008:administration & dosage*
D000318:Adrenergic beta-Agonists; D013726:Terbutaline