BRONCHODILATORY AND CIRCULATORY EFFECTS OF 2 DOSES OF A BETA-2-AGONIST (TERBUTALINE) INHALED WITH IPPB IN PATIENTS WITH REVERSIBLE AIRWAYS OBSTRUCTION

  • 1 January 1976
    • journal article
    • research article
    • Vol. 57  (5) , 252-258
Abstract
A .beta.2-receptor agonist, terbutaline (Bricanyl), in doses of 2.5 and 5 mg was inhaled by IPPB [intermittent positive pressure breathing] 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 (peak expiratory flow rate] or FEV1.0 [forced expiratory volume in 1 s]. One minute after the inhalation of 2.5 mg, PEFR 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 [vital capacity] showed similar changes with a tendency towards greater and longer effects after the larger dose. Heart rate did not change, while 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. Patients 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. Recent findings of drug-induced tolerance to .beta.-stimulating agents in the heart and skeletal muscles with preservation of good effects on the airway smooth muscles is supported, shown here as having a good residual bronchodilatory effect with clinically non-important effects on heart rate and tremor.