Randomised cross-over comparison of five inhaler systems for bronchodilator therapy.

The pharmacological efficacy of beta-2 agonists such as bronchodilators is well established, yet many patients fail to obtain optimum benefit from conventional metered-dose inhalers. This is usually because of difficulty in achieving adequate co-ordination between activation of the aerosol and inhalation. To some extent this problem can be alleviated by detailed personal instruction and re-instruction, but the medical or paramedical staff needed to do this may be unavailable and in any case their time is expensive. To increase the benefit obtained from bronchodilators, therefore, pharmaceutical companies have produced a variety of devices, eg, large-volume (750 ml) spacers (Nebuhaler, Volumatic) which enclose a cloud of aerosol, obviating the need for actuation-inhalation co-ordination, and breath actuated dry-power inhalers with (Rotahaler, Diskhaler) or without (Turbohaler) carrier powders. Subsequent compliance with treatment is dependent upon the acceptability of the inhaler device to the patient.