Response to bronchodilator drug administration by a new reservoir aerosol delivery system and a review of other auxiliary delivery systems

The influence of formulation and spacer device on the in vitro performance of solution chlorofluorocarbon-free propellant-driven metered dose inhalers

The purpose of this study was to evaluate the hypothesis that spacer devices have limited effect on the in vitro fine particle dose emitted from solution metered dose inhalers containing different proportions of HFA134a [1,1,1,2,-tetrafluoroethane] propellant. Two solution formulations (80% and 97.5% wt/wt HFA134a) were tested across the actuator alone, actuator plus Aerochamber, and Ace holding chamber. Particle size distributions were determined using laser diffraction (LD) and cascade impaction (CI). Multimodal particle size distributions were identified using LD. CI analyses were characterized by a major mode located at approximately 0.5 microm. The fine particle dose emitted from the inhaler spacer combinations containing 97.5% HFA134a was independent of the device setup used. Fine particle doses were influenced by spacer setup in 80% HFA134a formulations, indicating different plume dynamics of low vapor pressure formulations. Sampling inlet deposition was approximately 0 when spacer devices were used with either formulation. When spacers were not used, sampling inlet deposition was increased significantly. However, inlet deposition with the 97.5% HFA134a formulation was significantly less than that of the 80% HFA134a formulation (approximately 25% of emitted dose compared with 69%, respectively). Thus, high propellant concentration formulations appear to have more robust in vitro performance. This is particularly important given the preponderance of poor patient compliance that is associated with spacer use. High propellant concentrations had the advantage of fine particle doses that were independent of the device setup and significantly lowered sampling inlet deposition when no spacer was used.

Early lung absorption profile of non-CFC salbutamol via small and large volume plastic spacer devices

AIMS

To evaluate the lung dose of a non-CFC salbutamol metered dose inhaler (MDI) formulation via three commonly used plastic spacer devices, of both large and small volume, compared with the MDI used on its own.

METHODS

Ten healthy volunteers were studied in a randomized single (investigator) blind crossover design. Single 1200 microg nominal doses of salbutamol from a non-CFC MDI (Airomir), as 12 sequential 100 microg puffs over 6 min, were delivered from the MDI alone and via two large volume spacer devices (Nebuhaler, Volumatic), and a small volume spacer (Aerochamber). All spacers were prewashed prior to each study day and mouth rinsing was performed after each drug sequence. Plasma salbutamol was measured at 5, 10, 15 and 20 min, with calculation of maximum (Cmax) and average (Cav) concentrations. This lung dose was assessed using the early lung absorption profile of salbutamol in the first 20 min after inhalation.

RESULTS

Both of the large volume spacers, the Nebuhaler and the Volumatic, delivered significantly more salbutamol than the MDI alone. For Cav this amounted to a 2.07-fold difference (95% CI 1.48-2.90) between Nebuhaler vs MDI, and a 1.49-fold difference (95%CI 1.19-1.87) between Volumatic vs MDI. The Nebuhaler also produced greater deposition than either the Volumatic or the Aerochamber spacers; Nebuhaler vs Volumatic: 1.39-fold difference (95% CI 1.09-1.76), Nebuhaler vs Aerochamber: 1.63-fold difference (95% CI 1.20-2.21). There were no significant differences between the Aerochamber and the MDI alone.

CONCLUSIONS

Using the early lung absorption profile, for administration of the same nominal dose, both of the large volume spacers (Nebuhaler and Volumatic) but not the small volume spacer (Aerochamber) delivered significantly more salbutamol than the MDI alone. The Nebuhaler also produced greater delivery than either the Volumatic or the Aerochamber spacer devices. Our results show that whilst lung delivery of non-CFC salbutamol MDI is improved by the use of a plastic spacer, there may be appreciable differences in performance, particularly between large and small volume devices.

Pharmacological treatment in acute exacerbations of chronic obstructive pulmonary disease

Exacerbations of chronic obstructive pulmonary disease (COPD) are usually treated with bronchodilator therapy, glucocorticoids and antibiotics. However, there are few experimental data on the effects of these agents in patients with acute COPD. A beta(2)-adrenoceptor agonist is usually given first because it can be expected to produce a rapid response. An anticholinergic agent should also be given when the patient is severely ill or responds inadequately to the beta(2) agonist. These agents can be administered via a nebuliser or using a metered-dose inhaler in conjunction with a spacer device. Glucocorticoids can accelerate recovery if the standard empirical regimens for acute exacerbations of asthma are used, although a longer treatment duration appears to be required. Theophylline provides little additional benefit in patients who receive frequent doses of inhaled bronchodilators and an adequate dosage of a glucocorticoid. Although the role of bacterial infections is not completely understood, the use of antibiotics is justified in patients with severe airflow limitation who have febrile tracheobronchitis.

Dose response study of ipratropium bromide aerosol on maximum exercise performance in stable patients with chronic obstructive pulmonary disease

BACKGROUND

Although the bronchodilating effect of inhaled anticholinergics has been established in patients with chronic obstructive pulmonary disease (COPD), their effects on exercise capacity are still controversial. Previous studies have suggested that the standard dosage hardly affects exercise tolerance, whereas higher doses might elicit an improvement. The aim of the present study was to determine the dose of ipratropium bromide aerosol that improves exercise performance using progressive cycle ergometry in patients with stable COPD.

METHODS

Twenty men with stable COPD of mean (SD) age 69.2 (4.6) years and forced expiratory volume in one second (FEV1) 1.00 (0.37) 1 were studied in a randomised double blind manner. Each patient received ipratropium bromide in doses of 240 micrograms, 160 micrograms, 80 micrograms, 40 micrograms, and placebo from a metered dose inhaler (MDI) with an InspirEase spacer on five separate days. Spirometric parameters were assessed before and at 30, 60, 90, and 120 minutes after each inhalation, and pulse rate and blood pressure were also measured immediately before each spirometric measurement. Symptom limited progressive (20 watts/min) cycle ergometer exercise tests were performed 90 minutes after each inhalation.

RESULTS

Ipratropium bromide in doses of 160 micrograms and 240 micrograms produced a greater increase in FEV1 than 40 micrograms or 80 micrograms ipratropium bromide at all time points. Doses of 160 micrograms and 240 micrograms ipratropium bromide also produced greater increases in maximal work load and maximal oxygen consumption than placebo, whereas 40 micrograms and 80 micrograms ipratropium bromide did not. There was a weak correlation between the change in FEV1 and the change in maximal work load (r = 0.45). No differences were found in pulse rate or blood pressure between the treatment and placebo groups, and no side effects were noted throughout the study.

CONCLUSIONS

A dose of at least four times the standard dose of ipratropium bromide from an MDI with a spacer device was necessary to improve maximal cycle exercise capacity in patients with stable COPD. Although the data from cycle ergometry cannot be directly applied to exercise performed during day to day activities, it is conceivable that the recommended doses of ipratropium bromide do not elicit the optimal clinical benefits.

A large volume spacer significantly reduces the effect of inhaled steroids on bone formation

Inhaled steroids are increasingly advocated as first line treatment for mild asthma. Some studies suggest that inhaled steroids suppress bone formation as reflected by a fall in plasma osteocalcin. Spacers have been shown to increase the proportion of inhaled aerosol that is deposited in the lungs and to reduce the amount swallowed. We measured plasma osteocalcin levels to determine the effect on bone formation of inhaled beclomethasone dipropionate (BDP) with and without a 750 ml spacer in a double-blind, randomised, placebo-controlled, cross-over study. Twenty-six healthy male volunteers took BDP 500 micrograms (two puffs of Becloforte) together with two puffs of placebo, inhaled twice daily for seven days. One inhaler was taken directly while the other was inhaled through a 750 ml spacer. After a two week washout period, the inhalers were exchanged so that BDP was taken by the alternate route for a further seven days. Fasting plasma osteocalcin levels were measured at 09.00 h before and at the end of each week. After a week of BDP taken directly (without a spacer), osteocalcin levels fell from 11.8 (SEM 0.6) ng/ml to 9.5 (SEM 0.5) ng/ml (p < 0.001). After a week of BDP taken through a spacer, osteocalcin levels fell from 12.1 (SEM 0.5) ng/ml to 11.1 (SEM 0.5) ng/ml (p < 0.001). The fall in osteocalcin when a spacer was used was significantly less than when BDP was taken directly (p < 0.005). This is likely to be because the systemic effects on bone are caused by swallowed rather than inhaled BDP, and this is limited by the use of a spacer. Spacers should be more widely prescribed with inhaled steroids. Further prospective studies are indicated to evaluate whether spacers protect bone mass.

Physiological changes due to age. Implications for respiratory drug therapy

The pulmonary system is modified in various ways over time and it is particularly vulnerable to environmental insults. Of particular interest are the implications of aging for therapy of respiratory illnesses. The changes in pulmonary structure and function due simply to aging, and changes due to diseases, should be distinguished from each other. The great reserve function of the lung permits reasonable physical capacity in healthy individuals despite aging changes. In principle, loss of function equivalent to more than one lung is necessary to impair aerobic capacity at any age. Elderly people are subject to the same respiratory diseases as younger adults but may manifest them differently. They may present in atypical ways such as in bacterial pneumonia, tuberculosis, and asthma, all modified by anatomical alterations or deterioration of immunological defence mechanisms. Accumulation of toxic substances over time such as cigarette smoke or environmental pollutants may give rise to chronic bronchitis, emphysema, bronchogenic carcinoma and interstitial lung disease. Changes in the number or function of airway receptors modulate responses to bronchodilator drugs. Chronic inflammation of the bronchial wall has blurred the distinction between traditional asthma and chronic bronchitis and emphysema, and similar drug therapy can be useful for all. Adverse reactions to respiratory drugs such as theophylline, oral corticosteroids, and isoniazid increase with age. As more data accumulate, drug therapy of respiratory diseases in older patients will become more effective and safer.

Improvement of pressurised aerosol deposition with Nebuhaler spacer device

The effect on aerosol deposition from a pressurised metered dose inhaler of a 750 cm3 spacer device with a one way inhalation valve (Nebuhaler, Astra Pharmaceuticals) was assessed by means of an in vivo radiotracer technique. Nine patients with obstructive lung disease took part in the study. The pattern of deposition associated with use of a metered dose inhaler alone was compared with that achieved with the spacer used both for inhalation of single puffs of aerosol and for inhalation of four puffs actuated in rapid succession and then inhaled simultaneously. On each occasion there was a delay of 1 s between aerosol release and inhalation, simulating poor inhaler technique. With the metered dose inhaler alone, a mean (SEM) 8.7 (1.8)% of the dose reached the lungs and 80.9 (1.9)% was deposited in the oropharynx. With single puffs from the spacer 20.9 (1.6)% of the dose (p less than 0.01) reached the lungs, only 16.5 (2.3)% (p less than 0.01) was deposited in the oropharynx, and 55.8 (3.1)% was retained within the spacer itself. With four puffs from the spacer 15.2 (1.5)% reached the lungs (p = 0.02 compared with the metered dose inhaler alone, p less than 0.01 compared with single puffs from the spacer), 11.4 (1.2)% was deposited in the oropharynx, and 67.5 (1.8)% in the device itself. It is concluded that the spacer device gives lung deposition of metered dose aerosols comparable to or greater than a correctly used inhaler and oropharyngeal deposition is greatly reduced. The spacer should be used preferably for the inhalation of single puffs of aerosol but may also be used for the inhalation of up to four puffs actuated in rapid succession and then inhaled simultaneously.