Trial of Bronchodilator Drugs Given by Metered Aerosol with a Comparison of Two Bedside Methods of Estimating Airway Resistance

The most popular current method of inhalation bronchodilator therapy in asthma and bronchitis is by dry aerosol, stored in small cartridges under pressure and delivered in metered doses. There is evidence that this method is superior to conventional wet aerosol inhalation in delivering an effective dose with greater economy (Bouhuys, 1963 ; Feinmann and Newell, 1963). This paper reports a comparison of three proprietary dry aerosol bronchodilator products and a placebo of inert propellant. The active drugs were isoprenaline sulphate (Medihaler-iso-Forte) and two newer preparations?Bronchi lator and orciprenaline (Alupent). Bronchilator is a triple combination of two sympathomimetic amines (isoetharine and phenylephrine) and an antihistamine (thenyldiamine). The sympathomimetic amine isoetharine was found to be as effective as 1% isoprenaline without pro ducing systemic upsets (Herschfus et al., 1951). It is an effective antagonist of histamine-induced bronchoconstriction in the guinea-pig, an action that is enhanced by the addition of the antihistamine thenyldiamine hydrochloride (Lands et al., 1958). The triple aerosol has been shown to be of value in asthma and to be largely free of side-effects (Spielman, 1961 ; Goldfarb and Romanoff, 1962 ; Siegel, 1962). The British reports to date have confirmed the value of this preparation in both asthma and bronchitis (El-Shaboury, 1964 ; Jacobsen and Prime, 1964). Orciprenaline (Alupent), an analogue of isoprenaline, has been ?hown to be an effective bronchodilator when given by tablet, injection, or conventional wet aerosol (Zidek, 1961 ; G?nthner, 1961 ; Myers and Coltman, 1963 ; Kennedy and Jackson, 1963 ; Edwards, 1964). The above reports suggest that orciprenaline is superior to isoprenaline in being less toxic and in having a more prolonged action. There is little known, however, about the comparative effectiveness of orciprenaline given as the metered dry aerosol. In addition, this investigation was planned to compare two instruments commonly used for estimating airway resistance at the bedside and in the consulting-room. These are the peak-flow meter and the portable bellows spirometer.