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A comparison of the actions of different bronchodilators in asthma
  1. Bernard J. Freedman1,
  2. Peter Meisner2,
  3. G. B. Hill3
  1. 1Dulwich Hospital, King's College Hospital Group, London, S.E.22
  2. 3General Register Office, Somerset House, London, W.C.2

    Abstract

    The actions of the following pressurized bronchodilators were compared by administration to 24 asthmatics: (1) Medihaler Iso Forte, (2) Alupent, (3) Medihaler-duo, (4) Bronchilator, and (5) Prenomiser Plus. These contained one or more of the following: isoprenaline, orciprenaline, isoetharine, phenylephrine, atropine methonitrate, and thenyldiamine. The dose was a single discharge from the container. The response was assessed by calculating the mean percentage change in F.E.V. at intervals after inhalation.

    The mean peak rises were respectively (1) 49·4%, (2) 43·6%, (3) 36·2%, (4) 33·5%, and (5) 23·5%. The amplitude of peak response to isoprenaline was related to the logarithm of the dose. Weight for weight, orciprenaline had a peak bronchodilator activity 41·5% that of isoprenaline and isoetharine 50%. The preparations did not differ significantly in the time taken to reach maximum response, which varied from 5 to 60 minutes; three-quarters of the maxima occurred within 15 minutes.

    The half-life for Alupent was 2 hours; for Medihaler-duo, which contains 240 μg. of phenylephrine per dose, it was 1¼ hours; for the remaining preparations it was about 1 hour. The decay rate, after the first half-hour, was 6% of the basal F.E.V. per hour for Medihaler-duo; for the other preparations it was 10-12%. In the doses given, Alupent yielded 20% and 30% increases lasting 130 and 67 minutes; after Medihaler Iso Forte these lasted 78 and 46 minutes. Similar comparative experiments, designed to eliminate effects of dosage difference, are desirable. Rebound bronchoconstriction occurred in 23% of 92 experiments. There was no response to propellent alone. The mean percentage change in F.E.V. may not be the best way of expressing results.

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    Footnotes

    • 2 Present address: Lewisham Hospital, London, S.E.13

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