Comparison of terbutaline and placebo from a pressurised metered dose inhaler and a dry powder inhaler in a subgroup of patients with asthma.

BACKGROUND--Reversibility after administration of an inhaled bronchodilator is not always demonstrable in patients with asthma. Bronchodilator aerosol-induced bronchoconstriction has also been reported to occur in some patients. METHODS--Fifteen selected patients showing < 10% improvement in forced expiratory volume in one second (FEV1) when tested with four doses of salbutamol (0.1 mg/dose) or terbutaline (0.25 mg/dose) from a pressurised metered dose inhaler (MDI) participated in two randomised, double blind studies. They received 2.0 mg terbutaline (4 x 2 doses of 0.25 mg) or a corresponding placebo from an MDI connected to a 750 ml spacer, and 1.0 mg (2 x 0.5 mg) terbutaline or placebo from a multidose dry powder inhaler free of additives (Turbohaler). RESULTS--Inhalation of placebo MDI resulted in a mean (SD) decrease in FEV1 of 20.5 (14.1)% (range -42.9% to +2.6%). In 14 patients inhalation of 2.0 mg terbutaline MDI with spacer resulted in < 10% improvement (mean increase 3.1 (6.0)%). One mg of terbutaline via a Turbohaler resulted in improvements in FEV1 of > 15% in eight patients (mean increase 16.0 (9.7)%). The improvement was < 10% in four patients. Use of placebo Turbohaler did not affect airway calibre (mean change 0.2 (2.9)%). CONCLUSIONS--Additives of MDIs may cause bronchoconstriction in some patients with asthma. In these patients inhalation from a pressurised metered dose inhaler is more likely to decrease the bronchodilator response than inhalation from an additive-free inhaler. The frequency of this phenomenon is unknown.     

Comparison of bronchodilator responses and deposition patterns of salbutamol inhaled from a pressurised metered dose inhaler, as a dry powder, and as a nebulised solution.

The lung dose and deposition patterns of drug delivered by dry powder inhaler are not known. The effects of inhaling 400 micrograms salbutamol delivered by dry powder inhaler (two 200 micrograms salbutamol Rotacaps), by pressurised metered dose inhaler, and by Acorn nebuliser were studied in nine subjects with chronic stable asthma. Technetium-99m labelled Teflon particles were mixed with micronised salbutamol in the pressurised metered dose inhaler and in the capsules; technetium-99m labelled human serum albumin was mixed with the salbutamol solution for the nebuliser study. The pressurised metered dose inhaler deposited 11.2% (SEM 0.8%) of the dose within the lungs; this was significantly more than the dose deposited by the dry powder inhaler (9.1% (0.6%], but did not differ significantly from the dose delivered by the nebuliser (9.9% (0.7%]. Distribution within the peripheral third of the lung was significantly greater with the nebuliser than with the other two systems; FEV1 improved to a significantly greater extent after inhalation of 400 micrograms salbutamol from the pressurised metered dose inhaler (35.6% from baseline) than from the nebuliser (25.8%) or dry powder inhaler (25.2%). Thus after inhalation of similar doses of salbutamol a larger proportion of drug was deposited within the lungs when it was inhaled from a metered dose inhaler than from a dry powder system; the nebuliser achieved the greatest peripheral deposition. The bronchodilator response seems to depend on the amount of drug within the lungs rather than its pattern of distribution.     

Domiciliary comparison of terbutaline treatment by metered dose inhaler with and without conical spacer in severe and moderately severe chronic asthma.

The bronchodilator response to cumulative doses of terbutaline administered by metered dose inhaler with and without a conical spacer device and by Acorn nebuliser has been compared in groups of patients with chronic severe and moderately severe asthma. After laboratory studies the patients undertook a randomised domiciliary crossover comparison of bronchodilator response to terbutaline given by metered dose inhaler with and without a spacer device, during which the severity of asthma was assessed by thrice daily recordings of peak expiratory flow (PEF) and symptom score. Improvement in FEV1 produced in the laboratory by the metered dose inhaler with spacer device was significantly greater than by metered dose inhaler alone (p less than 0.001) and similar to that from the nebuliser in both asthmatic groups throughout a range of terbutaline doses. In the domiciliary comparison mean midday and evening PEF rates were significantly higher with the use of the spacer device both in those with severe (p less than 0.01) and in those with moderately severe (p less than 0.05) asthma, and mean morning PEF was significantly higher in the severe group (p less than 0.05). The spacer device also produced a significant improvement in symptom score in both the severe and the moderately severe groups (p less than 0.05). Regular domiciliary use of the spacer device with the metered dose inhaler improves bronchodilator response, particularly in patients with chronic severe asthma, and may be a useful alternative to nebuliser treatment.     

Imaging of the airways by bronchoscintigraphy for the study of mucociliary clearance.

A method for functional imaging of the large airways (bronchoscintigraphy) has been developed. It is based on the administration of aerosolised albumin labelled with technetium-99m using a special inhalation technique to produce central airway deposition. The method was evaluated as a measure of mucociliary clearance by recording the movement of radioactivity in the airways of 11 healthy, non-smoking subjects on two separate days. A series of bronchoscintigrams was acquired at five minute intervals for two hours after termination of the inhalation. After the first bronchoscintigram 1.25 mg terbutaline or placebo was administered from a metered dose inhaler (five puffs) according to a randomised, double blind, crossover design. The scintigrams were evaluated blind. After terbutaline the segmental bronchi were no longer visible after a median time of 10 minutes, the lobar bronchi after 20 minutes and the main bronchi after 30 minutes. In six cases the trachea was cleared after two hours. After placebo the segmental bronchi disappeared after a median of 15 minutes, but at two hours half the lobar bronchi remained visible. In only two cases was it no longer possible to see the main bronchi or the trachea. It is concluded that bronchoscintigraphy can be used to examine regional mucociliary clearance in healthy subjects and that terbutaline significantly increases the clearance of the deposited radioactive aerosol.     

Comparison of three techniques of inhalation on the airway response to terbutaline

The relative efficiency of the metered dose inhaler (MDI), the MDI attached to a pear shaped extension tube (PET), and the Inspiron Mini-Neb nebuliser were assessed in eight normal and eight asthmatic subjects. Subjects inhaled the same increasing doses of terbutaline with each technique on different occasions and the response was measured as specific airway conductance (sGaw) and, in the asthmatic patients only, as FEV1. The PET produced greater bronchodilatation than either the MDI or the nebuliser in both normal and asthmatic subjects. Serum terbutaline concentrations were similar after the PET and MDI in the normal subjects, but were lower with the PET in the asthmatic patients. The nebuliser produced about the same amount of bronchodilatation as the MDI--slightly less in the normal subjects and slightly more when assessed as FEV1 in the asthmatic subjects. Serum terbutaline concentrations were lower after the nebuliser than after the MDI in both groups of subjects. For patients with moderately severe airways obstruction requiring large doses of beta agonist, the nebuliser will produce an amount of bronchodilatation similar to the MDI with lower blood levels. Overall, the PET produced greater bronchodilatation than either of the other two methods of inhalation, with low serum terbutaline concentrations similar to those produced by the nebuliser in the asthmatic patients.     

Review of therapeutically equivalent alternatives to short acting beta(2) adrenoceptor agonists delivered via chlorofluorocarbon-containing inhalers

BACKGROUND: To study the transition from metered dose inhalers using chlorofluorocarbons as propellants (CFC-MDIs) to non-CFC containing devices, a systematic review was conducted of clinical trials which compared the delivery of salbutamol and terbutaline via CFC-MDIs and non-CFC devices. METHODS: Papers were selected by searching electronic databases (Medline, Cochrane, and BIDS) and further information and studies were sought from pharmaceutical companies. The studies were assessed for their methodological quality. RESULTS: Fifty three relevant trials were identified. Most were scientifically flawed in terms of study design, comparison of inappropriate doses, and insufficient power for the determination of therapeutic equivalence. Differences between inhaler devices were categorised according to efficacy and potency. Most trials claimed to show therapeutic equivalence, usually for the same doses from the different devices. Two commercially available salbutamol metered dose inhalers using a novel hydrofluorocarbon HFC-134a as propellant were equally as potent and efficacious as conventional CFC-MDIs, as were the Rotahaler and Clickhaler dry powder inhalers (DPIs). Evidence suggests that a dose of 200 microg salbutamol via CFC-MDI may be substituted with 200 microg and 400 microg of salbutamol via Accuhaler and Diskhaler DPIs, respectively. Terbutaline delivered via a Turbohaler DPI is equally as potent and efficacious as terbutaline delivered via a conventional CFC-MDI. CONCLUSIONS: When substituting non-CFC containing inhalers for CFC-MDIs, attention must be given to differences in inhaler characteristics which may result in variations in pulmonary function.     

Inhibition by sodium cromoglycate of bronchoconstriction stimulated by respiratory heat loss: comparison of pressurised aerosol and powder

The protective effect was examined of three doses (2, 10, and 20 mg) of sodium cromoglycate inhaled from a pressurised metered dose inhaler on the response to isocapnic hyperventilation of cold dry air in 10 asthmatic subjects. This was compared with the effect of cromoglycate powder (20 mg) inhaled from a Spincap and with placebo given on two occasions. The medications were inhaled on separate days, in random order and with the use of a double blind double dummy technique, 20 minutes before isocapnic hyperventilation of two fold increasing volumes of air (-15 degrees C, 0% humidity) to produce a 20% fall in the post-treatment FEV1. The response was expressed as the provocative dose of respiratory heat loss required to cause a fall in FEV1 of 15% (PD15, kcal/min). The mean baseline spirometric indices exceeded 85% of predicted normal values on each test day; both placebo treatments reduced the baseline FEV1 by comparison with all active treatments (p less than 0.0001). Comparison of the PD15 on the two placebo days confirmed excellent reproducibility. All doses of cromoglycate shifted the respiratory heat loss dose-response curve to the right of the placebo curve; PD15 after all active treatments exceeded PD15 after placebo (p less than 0.0001). There was no cromoglycate dose-response relationship between the three doses of aerosol (p greater than 0.05), or between any dose of aerosol and powder (p greater than 0.05). It is concluded that cromoglycate aerosol inhaled from a pressurised inhaler in a dose of 2 mg gives the same magnitude of protection against bronchoconstriction stimulated by airway cooling as 20 mg of pressurised aerosol or powder from a Spincap.     

Effect of an extension tube on the bronchodilator efficacy of terbutaline delivered from a metered dose inhaler.

A double-blind within-patient investigation was performed to determine whether the interposition of an extension tube (10 cm length X 3.2 cm diameter) between a metered dose inhaler and the mouth alters the bronchodilator efficacy of terbutaline sulphate. On two consecutive study days 14 adult patients with stable reversible airways obstruction inhaled a cumulative dose of 500 micrograms of terbutaline which was delivered from a metered dose inhaler with or without the extension tube attached and received placebo in a similar manner. The drug was inhaled in doses of 125, 125, and 250 micrograms at 20 minutes intervals. The following measurements were made: forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow rate (PEFR), thoracic gas volume (TGV), and specific airways conductance (sGaw). These were done immediately before and at five and 15 minute intervals after each dose, and were repeated 90, 120, 180, 240, and 300 minutes after the first inhalation of terbutaline. Administration of terbutaline with and without an extension tube achieved significant bronchodilation at all dose levels in all respiratory variables (p < 0.001). There was no statistically significant difference in FEV1, FVC, PEFR, and sGaw values at any time or dose level with either method of administration. The use of the extension tube did not impair the efficacy or duration of action of inhaled terbutaline.     

Improvement of drug delivery with a breath actuated pressurised aerosol for patients with poor inhaler technique.

BACKGROUND The metered dose inhaler is difficult to use correctly, synchronising actuation with inhalation being the most important problem. A breath actuated pressurised inhaler, designed to help patients with poor inhaler technique, was compared with a conventional metered dose inhaler in terms of aerosol deposition and bronchodilator response. METHODS Radioaerosol deposition and bronchodilator response to 100 micrograms salbutamol were measured in 18 asthmatic patients, who inhaled from a conventional metered dose inhaler by their own chosen metered dose inhaler technique, from a conventional metered dose inhaler by a taught metered dose inhaler technique, and from a breath actuated pressured inhaler (Autohaler). RESULTS In the 10 patients who could coordinate actuation and inhalation of the inhaler on their own deposition of aerosol in the lungs and bronchodilator response were equivalent on the three study days. By contrast, in the eight patients who could not coordinate the mean (SEM) percentage of the dose deposited in the lungs with their own inhaler technique (7.2% (3.4%] was substantial lower than those attained by the taught metered dose inhaler technique (22.8% (2.5%] and by Autohaler (20.8% (1.7%]. CONCLUSION Although of little additional benefit to asthmatic patients with good coordination, the Autohaler is potentially a valuable aid to those with poor coordination, and should be considered in preference to a conventional metered dose inhaler in any patient whose inhaler technique is not known to be satisfactory.     

Inhaled frusemide and exercise-induced bronchoconstriction in children with asthma.

BACKGROUND--Nebulised frusemide has been shown to be protective against bronchoconstricting stimuli in adult asthmatic subjects and against cold air challenge in children. Animal studies suggest that inhaled frusemide may be more effective in the young. METHODS--A double blind placebo, controlled, crossover study on the effect on exercise of pretreatment with frusemide (20 mg) from a metered dose inhaler via a large volume spacer (Volumatic) was performed in 12 asthmatic children. Exercise testing consisted of eight minutes of running on a treadmill in an environmentally controlled laboratory. RESULTS--Deterioration in lung function was less after frusemide than after the placebo exercise tests. The mean (95% CI) maximum percentage falls in forced expiratory volume in one second (FEV1) were 14.4% (7.7 to 21.0) for placebo and 5.7% (2.3 to 9.0) for frusemide. CONCLUSIONS--Inhaled frusemide via a metered dose inhaler reduces exercise-induced bronchoconstriction in children.     

Effect of ipratropium bromide on mucociliary clearance and pulmonary function in reversible airways obstruction.

The effects of (a) regular use for one week and (b) a single dose of a synthetic anticholinergic (ipratropium bromide) on lung mucociliary clearance and as a bronchodilator was ascertained in a controlled, double-blind, cross-over study in 12 patients with reversible airways obstruction (mean increase in FEV after isoprenaline: 17% range 10-50%). Two puffs from a metered dose inhaler of either placebo (propellants only) or drug (40 microgram) were administered four times a day for one week (regular use), and mucociliary clearance was measured, by radioaerosol tracer, at the end of each treatment period and after a control period in which no treatment was given. On the mornings of the measurements after the placebo and drug periods one final dose (single dose) of ipratropium (40 microgram) or placebo was given 2.5 hours before the start of the test. There was no statistically significant difference between the three mean mucociliary clearance curves (control, placebo, and drug) for the group; however, there was a significantly greater penetration towards the periphery of the lung of the tracer in the test after drug administration compared with the other two. This increased penetration was attributed to bronchodilatation caused by the drug. Ipratropium bromide does not appear to impair mucociliary clearance, and it acts an effective bronchodilator.     

Lung bioavailability of generic and innovator salbutamol metered dose inhalers.

BACKGROUND: The aim of this study was to determine whether significant differences exist in lung bioavailability between generic (Salamol, Salbulin) and innovator (Ventolin) formulations of inhaled salbutamol given by metered dose inhalers. METHODS: Ten healthy volunteers of mean age 20.5 years with a forced expiratory volume in one second (FEV1) of 112.1% predicted were studied in a randomised double blind single dosing crossover study. Salbutamol, 1200 micrograms, was given with mouth rinsing and lung bioavailability was assessed by measuring plasma salbutamol levels and urine excretion of salbutamol. RESULTS: No differences were seen between innovator and generic salbutamol metered dose inhalers in plasma salbutamol levels, urinary salbutamol excretion, or extrapulmonary beta 2 activity. The maximum plasma salbutamol concentration (mean Cmax) and time to maximum concentration (median Tmax) were: Ventolin (2.93 ng/ml, 10 minutes), Salbulin (3.01 ng/ml, 10 minutes), Salamol (3.33 ng/ml, 10 minutes). The geometric mean ratio and 95% confidence interval for Cmax were: Salbulin/Ventolin 1.02 (0.69 to 1.41) and Salamol/Ventolin 1.13 (0.94 to 1.35). CONCLUSIONS: No differences are apparent between the two generic and innovator formulations of salbutamol metered dose inhaler in terms of lung bioavailability.     

Use of a special inhaler attachment in asthmatic children.

Asthmatics often find difficulties in using an aerosol inhaler correctly as they are unable to co-ordinate the release of a bolus of drug to coincide with an inspiratory effort. This is especially the case with children. The addition of a special attachment to an ordinary inhaler overcame this problem. Twelve asthmatic children produced significantly better PEFR measurements when 0.25 mg terbutaline sulphate was administered via an inhaler with the attachment than when an ordinary inhaler was used alone.     

Morning serum cortisol concentrations after 2 mg inhaled beclomethasone dipropionate in normal subjects: effect of a 750 ml spacing device.

Large spacing devices have been shown to provide more selective delivery of an inhaled steroid to the lung but the effect on the hypothalamo-pituitary-adrenal suppression associated with high dose inhaled corticosteroids has been little studied. The effect of a large spacing device (Volumatic; 750 ml) on suppression of 0900 h cortisol after 2 mg inhaled beclomethasone dipropionate was therefore investigated in normal, healthy volunteers. Twenty four subjects (12 male, 12 female) took part in a randomised, double blind, placebo controlled cross over study in which a single dose of 2 mg beclomethasone dipropionate was taken at 2300 h on two occasions seven days apart, once from a metered dose inhaler alone and once from a metered dose inhaler attached to a 750 ml spacing device. The 0900 h serum cortisol concentration was the same on the morning before each administration (468 nmol/l, 95% confidence interval (CI) 390-561 nmol/l, day 1 v 479 nmol/l, 95% CI 463-494 nmol/l, day 8). The 0900 h serum cortisol concentration the following morning, however, was lower when 2 mg beclomethasone dipropionate was given by metered dose inhaler alone (182 (95% CI 128-264) nmol/l) than when it was given by a spacing device (363 (95% CI 281-475) nmol/l). These results suggest that a large spacing device attached to a metered dose inhaler may decrease the risk of hypothalamo-pituitary-adrenal suppression by high dose inhaled steroid treatment.     

Effect of a volumatic spacer and mouth rinsing on systemic absorption of inhaled corticosteroids from a metered dose inhaler and dry powder inhaler.

BACKGROUND: High doses of inhaled corticosteroids are absorbed systemically and may cause long term side effects. As rinsing the mouth out after use and inhaling through a spacing device may reduce systemic absorption this has been further investigated. METHODS: Three crossover studies were carried out to assess the effect of budesonide given by dry powder inhaler (Turbuhaler) with and without mouth rinsing and beclomethasone dipropionate given by metered dose inhaler with or without a spacing device (Volumatic) on serum cortisol concentrations and urinary cortisol excretion in patients with asthma taking an inhaled corticosteroid. Each treatment period was two weeks with in a two week washout period. Serum cortisol concentrations at 0800 hours on day 14 and the 24 hour urinary excretion of cortisol were measured. In study 1 24 patients taking beclomethasone dipropionate 500 micrograms twice a day inhaled with (n = 10) or without (n = 14) a Volumatic spacing device were switched to a budesonide dry powder inhaler, 600 micrograms to be taken twice a day without mouth rinsing. In study 2 10 patients took budesonide 800 micrograms twice a day with and without mouth rinsing and without swallowing the rinsing water. In study 3 17 patients took budesonide 800 micrograms twice daily with mouth rinsing and beclomethasone dipropionate 500 micrograms twice daily with the spacing device and mouth rinsing. RESULTS: In study 1 no difference was seen between budesonide without mouth rinsing and beclomethasone dipropionate without a spacer: beclomethasone with spacer caused less suppression of cortisol (mean (SD) serum cortisol concentration: beclomethasone and spacer 487(148), budesonide 368(145) nmol/l). In study 2 mouth rinsing caused less suppression of morning serum cortisol concentrations (rinsing 440(63), no rinsing 375(56) nmol/1). In study 3 there was no difference in serum or urinary cortisol concentrations between twice daily beclomethasone dipropionate 500 micrograms inhaled by Volumatic spacer or budesonide by Turbuhaler 800 micrograms twice daily, both with mouth rinsing. Individual serum cortisol values were within the normal range in all patients except one in study 1. CONCLUSION: Systemic absorption of a corticosteroid inhaled from a metered dose inhaler is reduced by using a spacing device and that from a dry powder inhaler by mouth rinsing.     

Delivery of propellant soluble drug from a metered dose inhaler.

The deposition of particulate suspensions delivered from a metered dose inhaler has been investigated extensively. The distribution of propellant, delivered from a metered dose inhaler, was studied by radiolabelling it with technetium-99m hexamethylpropyleneamine oxime. Andersen sampler measurements indicated that half of the dose was associated with particles in the size range 0.5-5 microns diameter. The preparation was administered to healthy subjects by inhalation and deposition was monitored with a gamma camera. Each lung image was divided into an inner, mid, and peripheral zone. The effects on deposition of varying the size of the delivery orifice (0.46, 0.61, and 0.76 mm internal diameters) and the effect of attaching a spacer were assessed. Lung deposition was independent of the orifice size within the actuator. Without the spacer the average dose deposited in the lungs was 39%, with 15% penetrating into the peripheral part of the lungs. Attachment of the spacer to the mouth-piece increased the mean lung deposition to 57% and reduced oropharyngeal deposition. The study has shown that propellant soluble drugs can be delivered efficiently to the lungs from a metered dose inhaler.     

Effect of four weeks'' high dose ipratropium bromide treatment on lung mucociliary clearance.

In a randomised, double blind crossover study the effect of high dose ipratropium bromide (200 micrograms three times daily given by metered dose inhaler for four weeks) on lung mucociliary clearance and on the wet weight and mean apparent viscosity of sputum was compared with that of placebo. Six smokers, six ex-smokers, and three non-smokers (12 men and three women, median age 60 years) were studied. Eight subjects had chronic obstructive lung disease (median FEV1 46% predicted) and seven had asthma (FEV1 70% predicted). Seven subjects produced sputum regularly, two of whom had asthma. Clearance of secretions was measured by an inhaled radioaerosol technique. The number of coughs and the wet weight, radioactive content, and mean apparent viscosity of sputum produced during the six hour observation period were recorded, as was the mean wet weight of sputum produced during the last two 24 hour periods ending each treatment. Comparison with placebo showed that treatment with high dose ipratropium bromide was associated with a significant increase in the penetration index of inhaled particles, but there was no significant change in alveolar deposition of particles or in tracheobronchial clearance, uncorrected or corrected for sputum expectorated. The wet weight of sputum produced, its radioactive content, and mean apparent viscosity were similar after treatment with ipratropium bromide and placebo. These results show that high dose inhaled treatment with the synthetic anticholinergic bronchodilator ipratropium bromide for four weeks is not associated with detectable modification of the clearance of secretions from the lungs, or of sputum volume or viscosity.     

Dose-response comparison of ipratropium bromide from a metered-dose inhaler and by jet nebulisation

The dose-response relationships of the anticholinergic bronchodilator drug ipratropium bromide were studied. Cumulative doses totalling 288 micrograms ipratropium were given by inhalation of a liquid aerosol from a Wright nebuliser to each of 10 patients with stable, moderately severe airflow obstruction. Up to 80% of the maximum achievable bronchodilator response, as assessed by a rise in the patients' mean forced expiratory volume in one second (FEV1), was obtained with a cumulative total dose of 72 micrograms; with additional doses beyond 72 micrograms there was no significant further improvement. In the same patients the effects of administration of cumulative doses of ipratropium to a total of 72 micrograms from a Wright nebuliser were compared with those achieved with a metered-dose inhaler. Bronchodilatation was assessed by measurement of peak expiratory flow rate, FEV1, forced vital capacity, thoracic gas volume and specific airways conductance (sGaw). No significant difference was observed in the response at any dose level between the wet and the dry aerosols. By fitting a curve to the mean values of FEV1 and sGaw an estimate was made of the dose of ipratropium bromide required to produce 99% of the achievable bronchodilator response. For FEV1 this dose was 78 micrograms when ipratropium was inhaled as a nebulised solution from the Wright nebuliser and 82 micrograms when it was inhaled from the metered-dose inhaler; for sGaw the respective values were 54 and 58 micrograms. In these patients with stable airflow obstruction there was no therapeutic advantage in the use of ipratropium bromide as a wet aerosol.     

Effects of cessation of terbutaline treatment on airway obstruction and responsiveness in patients with chronic obstructive pulmonary disease.

BACKGROUND: Cessation of regular therapy with inhaled beta 2 agonists in patients with asthma may lead to a temporary deterioration of lung function and airway responsiveness. Few such studies have been reported in patients with chronic obstructive pulmonary disease (COPD), so an investigation was carried out to determine whether rebound airway responsiveness and rebound bronchoconstriction also occurs in COPD and if there is any relationship with the dose of beta 2 agonist being used. METHODS: Lung function (forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF)), airway responsiveness (PC20 methacholine (PC20)) and symptoms were assessed in a double blind, placebo controlled crossover study during and after cessation of two weeks regular treatment with placebo, and low dose (250 micrograms) and high dose (1000 micrograms) inhaled terbutaline via a dry powder inhaler (Turbohaler) all given three times a day. Sixteen non-allergic patients with COPD of mean (SD) age 58.7 (6.5) years, FEV1 57.1 (12.8)% of predicted, and reversibility on 1000 micrograms terbutaline of 4.5 (3.5)% predicted were studied. PC20 and FEV1 were measured 10, 14, 34 and 82 hours after the last inhalation of terbutaline or placebo. Measurements performed at 10, 14, and 34 hours were expressed relative to 82 hour values in each period, transformed into an area under the curve (AUC) value and analysed by ANOVA. RESULTS: Mean morning and evening PEF increased during terbutaline treatment. PC20 and FEV1 did not change after cessation of terbutaline treatment. CONCLUSIONS: Cessation of regular treatment with both low and high dose inhaled terbutaline does not result in a rebound bronchoconstriction and rebound airway responsiveness in patients with COPD.     

Evaluation of the effectiveness of four different inhalers in patients with chronic obstructive pulmonary disease.

BACKGROUND--The percentage of patients inhaling their medication effectively varies widely, according to methods of assessment and inhalers used. This study was carried out to assess differences among four types of inhalers using inhaler-specific checklists. METHODS--Inhalation technique was evaluated in adult patients with chronic obstructive pulmonary disease (COPD). Inhalers investigated were either metered dose inhalers (MDIs) or the dry powder inhalers Turbohaler (Turbuhaler), Diskhaler, and Rotahaler. Errors were recorded against inhaler-specific checklists. From these, scores were derived by dividing the number of items correctly completed by the total number of items on the checklist and the result was expressed as a percentage. For every inhaler "essential actions" were identified and scores on these key manoeuvres were calculated. The percentage of patients performing all these essential actions correctly was also calculated. Scores were also compared with adjustment for differences in relevant patient characteristics. RESULTS--Important differences among inhalers were found. Of 152 patients with COPD (mean (SD) age 55.1 (8.7) years), those with MDIs performed worst, especially when only essential items were considered. Patients with a Diskhaler did best, although after correction for patient characteristics the differences tended to diminish. Only 60% of patients were able to perform all essential inhaler actions satisfactorily. Of those using the Diskhaler, 96% did so correctly, while the corresponding figure for those using the MDI was only 24%. CONCLUSIONS--Many patients with COPD use their inhaler ineffectively. After adjusting for patient characteristics, differences among inhalers, although less pronounced, persist. Patients using a Diskhaler made fewest errors, while most patients using MDIs made crucial mistakes.