Bronchodilatory and circulatory effects of two doses of a beta2-agonist (terbutaline) inhaled with IPPB in patients with reversible airways obstruction.
A beta2-receptor agonist, terbutaline (Bricanyl), in doses of 2.5 and 5 mg was inhaled by IPPB with a Bird Mark 8 in a double-blind cross-over randomized study on consecutive days in 12 patients with at least 15% reversibility of PEFR or FEV 1.0. One minute after the inhalation of 2.5 mg, PEFR had increased significantly; the greatest effect (+ 34%) was recorded after 120 min. After 5 mg the increase was more marked, with the greatest recorded effect (+ 43%) after 120 min; FEV1 and VC showed similar changes with a tendency towards greater and longer effects after the larger dose. Heart rate did not change. Systolic and diastolic blood pressures decreased at the most with 9 and 5 mmHg respectively, 30 min after 5 mg terbutaline. One patient reported tremor and palpitations 5 min after inhaling 5 mg. Our patients who were treated with beta-adrenergic drugs showed less systemic effects after the same dose of terbutaline than previously non-treated normal subjects in an earlier study. This may support recent findings of drug-induced tolerance to beta-stimulating agents in the heart and skeletal muscles with preservation of good effect on the airway smooth muscles, here shown as having a good residual bronchodilatory effect with clinically non-important effects on heart rate and tremor.
D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000188:drug therapy*; D001249:Asthma / Q000188:drug therapy*; D001775:Blood Circulation / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D001980:Bronchi / Q000187:drug effects*; D002986:Clinical Trials as Topic; D004341:Drug Evaluation; D005260:Female; D005541:Forced Expiratory Volume; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007384:Intermittent Positive-Pressure Breathing; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D013726:Terbutaline / Q000008:administration & dosage / Q000627:therapeutic use*; D013997:Time Factors; D014797:Vital Capacity / Q000187:drug effects
D013726:Terbutaline