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 bronchodilator aerosols with a median mass aerodynamic diameter of 2.8 microm induced stronger bronchodilatations than larger aerosols and that the dilatations were clinically relevant at low doses. To discover whether the bronchodilator effects of these low-dose monodisperse aerosols differed from those of standard dosages delivered by metered-dose inhalers, 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 predicted value inhaled a placebo aerosol, 8 microg of a 2.8-microm monodisperse ipratropium bromide aerosol and 40 microg from a metered-dose inhaler plus spacer; lung-function measurements followed. Data were analysed with repeated measurements analysis of variance (ANOVA). RESULTS: Greater 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-microm aerosol proved to be equivalent to the higher-dose metered-dose inhaler. CONCLUSION: By changing the polydisperse characteristic of inhaled aerosols to a monodisperse pattern, the dose of the drug administered can be reduced without loss of efficacy.

Optimal particle size for beta 2 agonist and anticholinergic aerosols in patients with severe airflow obstruction.

BACKGROUND: The optimal particle size of a beta 2 agonist or anticholinergic aerosol in patients with severe airflow obstruction is unknown. METHODS: Seven stable patients with a mean forced expiratory volume in one second (FEV1) of 37.9% of the predicted value inhaled three types of monodisperse salbutamol and ipratropium bromide aerosols with particle sizes of 1.5 microns, 2.8 microns, and 5 microns, respectively, and a placebo aerosol. The volunteers inhaled 20 micrograms salbutamol and 8 micrograms ipratropium bromide, after which lung function changes were determined and analysed with repeated measurements analysis of variance (ANOVA). RESULTS: Greater improvements in FEV1, specific airway conductance (sGaw) and maximum expiratory flow at 75%/50% of the forced vital capacity (MEF75/50) were induced by the 2.8 microns aerosol than by the other particle sizes. CONCLUSIONS: In patients with severe airflow obstruction the particle size of choice for a beta 2 agonist or anticholinergic aerosol should be approximately 3 microns.

Quantitative thallium-201 myocardial exercise scintigraphy in normal subjects and patients with normal coronary arteries.

Quantitative thallium-201 myocardial exercise scintigraphy was tested in two patient populations representing alternative standards for cardiac normality: group I comprised 18 male uncatheterized patients with a low likelihood of coronary artery disease (CAD); group II contained 41 patients with normal coronary arteriograms. Group I patients were younger, they achieved a higher rate-pressure product than group II patients; all had normal findings by physical examination and electrocardiography at rest and exercise. Group II patients comprised 21 females, 11 patients showed abnormal electrocardiography at rest, and five patients showed ischemic ST depression during exercise. Twelve patients had signs of minimal CAD. Twelve patients revealed abnormal visual and quantitative thallium findings, three of these patients had minimal CAD. Profiles of uptake and washout of thallium-201 were derived from both patient groups, and compared with normal limits developed by Maddahi et al. Furthermore, low likelihood and angiographically normal patients may differ substantially, and both sets of normal patients should be considered when establishing criteria for abnormality in exercise thallium imaging. When commercial software containing normal limits for quantitative analysis of exercise thallium-201 imaging is used in clinical practice, it is mandatory to compare these with normal limits of uptake and washout of thallium-201, derived from the less heterogeneous group of low-likelihood subjects, which should be used in selecting a normal population to define normality.