THE EFFICACY OF A LOW-DOSE, MONODISPERSE PARASYMPATHICOLYTIC AEROSOL COMPARED WITH A STANDARD AEROSOL FROM A METERED-DOSE INHALER

Objective: In previous experiments we showed that monodisperse broncho dilator aerosols with a median mass aerodynamic diameter of 2.8 mu m i nduced stronger bronchodilatations than larger aerosols and that the d ilatations were clinically relevant at low doses. To discover whether the bronchodilator effects of these low-dose monodisperse aerosols dif fered from those of standard dosages delivered by metered-dose inhaler s, we carried out a comparative trial. Methods: Ten stable outpatients with a mean forced expiratory volume in 1 s (FEV1) of 58.1% of the pr edicted value inhaled a placebo aerosol, 8 mu g of a 2.8-mu m monodisp erse ipratropium bromide aerosol and 40 mu g from a metered-dose inhal er plus spacer; lung-function measurements followed. Data were analyse d with repeated measurements analysis of variance (ANOVA). Results: Gr eater improvements than with placebo were evident for the forced vital capacity (FVC), the FEV1, the specific airway conductance (sGaw), the peak flow (PEF) and the maximum expiratory flow at 75% of the forced vital capacity (MEF75). In these cases, the low-dose 2.8-mu m aerosol proved to be equivalent to the higher-dose metered-dose inhaler. Concl usion: By changing the polydisperse characteristic of inhaled aerosols to a monodisperse pattern, the dose of the drug administered can be r educed without loss of efficacy.