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A critical comparison of the dose delivery characteristics of four alternative inhalation devices delivering salbutamol: pressurized metered dose inhaler, Diskus inhaler, Diskhaler inhaler, and Turbuhaler inhaler.

Salbutamol is a short-acting beta 2 agonist which is effective as a rescue therapy in the treatment of asthma. This study uses in vitro test methods to compare the capability of four alternative devices to deliver an accurate and precise dose of salbutamol. It is demonstrated that the conventional metered dose inhaler (MDI) achieves excellent accuracy and precision in dose delivery. Additionally, it is the most efficient inhaler in terms of generating in-vitro a fine particle fraction from the dose. A spacer device has been shown to further enhance the dosing characteristics. When tested over a wide range of inspiratory air flow rates, the Diskus (GlaxoWellcome, Hertfordshire, UK) has comparable accuracy and precision to the MDI tested at 60 L/min, and it offers an advantage over two alternative dry powder inhalers (DPIs), delivering a more consistent dose across the range of flow rates tested and being more efficient at generating a fine particle fraction than either Turbuhaler (Astra, Lund, Sweden) or Diskhaler (GlaxoWellcome) at both 28 and 60 L/min inspiratory flow rates. Diskus, Diskhaler, Ventolin, Volumatic, and Rotadisk are trademarks of the GlaxoWellcome Group of companies. The Accuhaler is the alternative to the Diskus in those countries where the Diskus trademark is not available. Inspiryl and Turbuhaler are trademarks of the Astra Group of companies.

Administration, Inhalation↗

Patient perceptions of an inhaled asthma medication administered as an inhalation powder via the Diskus or as an inhalation aerosol via a metered-dose inhaler.

OBJECTIVE: To evaluate patient preference, ease of use, and correctness of use of fluticasone propionate administered as inhalation powder via the Diskus (GlaxoSmithKline, Research Triangle Park, NC) and as inhalation aerosol administered via metered-dose inhaler (MDI). METHODS: In 154 patients 12 years of age and older with asthma and a history of MDI use, the Diskus and the MDI were compared in a randomized, open-label, 7-week crossover study. RESULTS: In patients who had used both devices, more found the Diskus easier to use (59%) and preferred it overall (60%) compared with the MDI (P < or = 0.025). Ninety-eight percent (for the MDI) vs 91% (for the Diskus) of patients were able to correctly perform all the maneuvers necessary to use the devices correctly by either viewing a single demonstration and/or reading the instructions for use. Ninety-four percent of all patients found it easier to tell the number of residual doses with the Diskus (P < 0.001), and 59% of patients indicated that they would most likely request the Diskus from their physician (P = 0.025). Compliance was significantly better with the Diskus; 91.1% of patients used the Diskus as directed compared with 78.6% for the MDI (P = 0.013). CONCLUSIONS: In patients exposed to both devices, the majority preferred the Diskus and found it easier to use compared with the MDI. Ninety-one percent of patients used the Diskus correctly with minimal training, and when given a choice, most indicated they would likely request the Diskus from their physicians. Together, these data indicate a significant level of acceptance of the Diskus device in this patient population.

Administration, Inhalation↗

Inhaled ciclesonide versus inhaled budesonide or inhaled beclomethasone or inhaled fluticasone for chronic asthma in adults: a systematic review.

BACKGROUND: Ciclesonide is a new inhaled corticosteroids licensed for the prophylactic treatment of persistent asthma in adults. Currently beclomethasone dipropionate, budesonide and fluticasone propionate are the most commonly prescribed inhaled corticosteroids for the treatment of asthma but there has been no systematic review comparing the effectiveness and safety ciclesonide to these agents. We therefore aimed to systematically review published randomised controlled trials of the effectiveness and safety of ciclesonide compared to alternative inhaled corticosteroids in people with asthma. METHODS: We performed literature searches on MEDLINE, EMBASE, PUBMED, the COCHRANE LIBRARY and various Internet evidence sources for randomised controlled trials or systematic reviews comparing ciclesonide to beclomethasone or budesonide or fluticasone in adult humans with persistent asthma. Data was extracted by one reviewer. RESULTS: Five studies met the inclusion criteria. Methodological quality was variable. There were no trials comparing ciclesonide to beclomethasone. There was no significant difference between ciclesonide and budesonide or fluticasone on the following outcomes: lung function, symptoms, quality of life, airway responsiveness to a provoking agent or inflammatory markers. However, the trials were very small in size, increasing the possibility of a type II error. One trial demonstrated that the combined deposition of ciclesonide (and its active metabolite) in the oropharynx was 47% of that of budesonide while another trial demonstrated that the combined deposition of ciclesonide (and its active metabolite) in the oropharynx was 53% of that of fluticasone. One trial demonstrated less suppression of cortisol in overnight urine collection after ciclesonide compared to fluticasone (geometric mean fold difference = 1.5, P < 0.05) but no significant difference in plasma cortisol response. CONCLUSION: There is very little evidence comparing CIC to other ICS, restricted to very small, phase II studies of low power. These demonstrate CIC has similar effectiveness and efficacy to FP and BUD (though equivalence is not certain) and findings regarding oral deposition and HPA suppression are inconclusive. There is no direct comparative evidence that CIC causes fewer side effects since none of the studies reported patient-based outcomes.

Administration, Inhalation↗

Inhaled nitric oxide for respiratory failure in preterm infants.

BACKGROUND: This section is under preparation and will be included in the next issue. OBJECTIVES: To determine whether, in preterm newborn infants who have hypoxic respiratory failure, treatment with inhaled nitric oxide improves oxygenation and reduces the rates of death, or adverse neurodevelopmental outcome. SEARCH STRATEGY: Electronic and hand searching of pediatric/neonatal literature and personal data files. SELECTION CRITERIA: Randomized and quasi randomized studies in preterm infants with hypoxic respiratory failure. Administration of inhaled nitric oxide. Clinically relevant outcomes, including death, oxygenation, intraventricular haemorrhage. DATA COLLECTION AND ANALYSIS: One randomized controlled trial of nitric oxide therapy was found in preterm infants with a high risk of developing bronchopulmonary dysplasia (Subhedar 1997). MAIN RESULTS: No significant effect of inhaled nitric oxide on any outcome variable was found. In particular there was no effect on the primary outcome variable of death or bronchopulmonary dysplasia. REVIEWER'S CONCLUSIONS: There is currently no published information to support the use of inhaled nitric oxide in preterm infants. Preterm infants should not be treated with inhaled nitric oxide except in the context of prospective, randomized controlled trials.

Administration, Inhalation↗

Early use of inhaled corticosteroids in the emergency department treatment of acute asthma.

BACKGROUND: Systemic corticosteroids therapy is central to the management of acute asthma The use of inhaled steroids may also be beneficial in this setting. OBJECTIVES: To determine the benefit of ICS for the treatment of patients with acute asthma managed in the emergency department (ED). SEARCH STRATEGY: Randomised controlled trials (RCTs) were identified from the Cochrane Airways Review Group register. Bibliographies from included studies, known reviews, and texts also were searched. SELECTION CRITERIA: Only RCTs or quasi-randomised trials were eligible for inclusion. Studies were included if patients presented with acute asthma to the ED or its equivalent, and were treated with ICS or placebo, in addition to standard therapy. Two reviewers independently selected potentially relevant articles, and then independently selected articles for inclusion. Methodological quality was independently assessed by two reviewers. DATA COLLECTION AND ANALYSIS: Data were extracted independently by two reviewers if the authors were unable to verify the validity of extracted information. Missing data were obtained from the authors or calculated from other data presented in the paper. MAIN RESULTS: Seven trials were selected for inclusion, but data were not available for one of them. In the six usable rials, (4 adult, 2 paediatric), a total of 352 patients were studied (179 ICS, 173 non-ICS treated). Patients treated with ICS were less likely to be admitted to hospital (OR: 0.30; 95% CI: 0.16, 0.57). This benefit was confined to patients not receiving concomitant systemic steroids. Such patients showed the same, but non-significant, trend towards reduced admissions compared to placebo treatment (OR 0.46; 95% CI: 0. 19, 1.11). In children, ICS appeared to be at least as effective as systemic steroids (OR 0.5; 95% CI: 0.24, 1.06). Patients receiving ICS demonstrated small, significant improvements in peak expiratory flows (PEFR WMD: 7%; 95% CI: 3, 13) and forced expiratory volumes (FEV-FEV1 WMD: 5.0%; 95% CI: 0.4, 9.7). The treatment was well tolerated, with few reported adverse side effects. REVIEWER'S CONCLUSIONS: Inhaled steroids reduced admission rates in patients with acute asthma who were not receiving concomitant systemic steroids. In children, inhaled steroids appear to be at least as effective as systemic steroids. Further research is needed to clarify the effect of ICS when used in addition to systemic corticosteroids, and to determine the optimal dose, agent, and frequency of ICS administration.

Acute Disease↗

Pilot study of bronchodilator response to inhaled albuterol delivered by metered-dose inhaler and a novel dry powder inhaler.

BACKGROUND: The metered-dose inhaler is currently one of the most prescribed methods of delivering drugs to the lungs. In the United States, most currently marketed metered dose inhalers use chlorofluorocarbons as the system propellant and require patient breath coordination. These factors lead to the need for a delivery system that is independent of propellants and patient coordination. OBJECTIVE: To compare the magnitude and time course of bronchodilation between albuterol delivered by Ventolin metered dose inhaler and albuterol sulfate powder (Rotacaps) delivered by a novel dry powder inhaler that generates a respirable drug aerosol over a range of inspiratory flow rates. METHODS: A single-center, single-dose, randomized, placebo-controlled, partial-blind, 3-way crossover study was conducted in an outpatient asthma Clinical Research Center. Twelve mild to moderate asthmatic patients 12 to 36 years of age participated in this study that involved three treatments, each separated by three to eight days, consisting of 2 puffs (90 micrograms/puff) albuterol by Ventolin metered-dose inhaler, two inhalations (100 micrograms/puff) albuterol sulfate powder (Rotacaps) by dry powder inhaler, and two inhalations (12.5 mg/inhalation) lactose powder by dry powder inhaler. Spirometry, blood pressure, and heart rate were measured at 30 minutes, 15 minutes, and immediately before treatment and then at 15, 30, 45, 60, 90, 120, 180, 240, and 300 minutes after each treatment. Serum potassium and glucose, and electrocardiograms were measured at 30 minutes before, and 30, 60, 90, and 180 minutes after each treatment. Endpoints were compared with analysis of variance. RESULTS: Five patients (one metered-dose inhaler and four dry powder inhaler) did not respond with > 15% FEV1 increase over baseline within 30 minutes. Metered-dose inhaler and dry powder inhaler mean FEV1 results, respectively, for 11 and 8 responders were 15 minutes in onset, 202.9 and 185.4 minutes in duration, 24.8% and 25.1% maximum change, and 18.6 and 18.2 area-under-FEV1-bronchodilation-curve. Statistical analysis of all patients and responders-only revealed both active treatments to be different from placebo (P = .0018), but not different from each other (P = .1291). No safety endpoints were significantly different among all three treatments (P > .10 for all safety endpoints). CONCLUSIONS: In this study, the dry powder inhaler safely and effectively delivered a commercially available albuterol sulfate powder (Rotacaps) into human lungs with bronchodilation comparable to Ventolin metered-dose inhaler.

Administration, Inhalation↗

Effect of terbutaline on mucociliary clearance in asthmatic and healthy subjects after inhalation from a pressurised inhaler and a dry powder inhaler.

BACKGROUND: beta Agonists have been shown to increase mucociliary clearance in some studies but not all. Whether the formulation of beta agonists affects mucociliary clearance is not known but may be important as the use of dry powder inhalers increases. METHODS: The effect of different methods of administration of inhaled terbutaline on mucociliary clearance and forced expiratory volume in one second (FEV1) was assessed in 10 patients with asthma and 10 healthy subjects. Terbutaline (1 mg) was administered through a metered dose inhaler with a spacer (Nebuhaler) or a dry powder inhaler (Turbuhaler), or both treatments were given, in a four way double blind, double dummy trial. Mucociliary clearance was measured by bronchoscintigraphy. RESULTS: Clearance of radioactivity from the lobar bronchi increased in the asthmatic patients by a median of 32% after terbutaline was given by metered dose inhaler and 55% after a combined dose of 2 mg from both inhalers (1 mg from each) compared with placebo but by only 9% after 1 mg of terbutaline was given by a dry powder inhaler. In the healthy subjects mucociliary clearance increased by 51% when terbutaline was given by a dry powder inhaler, by 66% when given by a metered dose inhaler, and by 66% when given by both inhalers combined. The effect of terbutaline on FEV1 was the same with each of the inhalers. CONCLUSION: Despite similar changes in FEV1 with the two formulations terbutaline increased mucociliary clearance significantly in asthmatic and healthy subjects when inhaled from a metered dose inhaler whereas when it was inhaled from a dry powder inhaler its effect was significant only in healthy subjects. The reason for the difference in asthmatic subjects is unclear, but may be associated with differences in the deposition of terbutaline.

Administration, Inhalation↗

Comparison of the lung absorption of FK224 inhaled from a pressurized metered dose inhaler and a dry powder inhaler by healthy volunteers.

FK224 is a cyclopeptide drug with poor oral absorption due to proteolysis in the gastrointestinal tract. The objectives of this study were to investigate the absorption of FK224 from the lung in healthy volunteers, and compare the pharmacokinetic profiles of FK224 after inhalation from a pressurized metered dose inhaler (pMDI) and dry powder inhaler (DPI). The pMDI (Suspension type, 1 mg as FK224/puff) and DPI (4 mg and 10 mg as FK224/capsule, using Spinhaler as the device) were developed by formulating the same micronized particles of FK224 which were premixed with beta-cyclodextrin (beta-CyD) to improve the solubility of FK224. In the case of pMDI, 1, 4 or 8 mg was inhaled by the corresponding number of puffs with the pMDI. In addition, the in vitro drug delivery characteristics of the inhalers were evaluated using a multistage liquid impinger. In both inhalers, it was observed that FK224 could be absorbed into the systemic circulation from the lungs of the healthy volunteers, and the AUC and C(max) were proportionally increased depending on the emitted dose after inhalation. However, the pharmacokinetic (PK) parameters for DPI were significantly higher than that of pMDI, in spite of usage of the same fine particles for the formulations in both inhalers. Based on the distribution from the in vitro examination, the fine particle dose, which is defined as the dose region delivered as particles <3.8 microm, was calculated from the emitted dose inhaled by the healthy volunteers. It was found that the PK parameters for both inhalers were proportionally increased depending on the predicted fine particle dose regardless of the type of inhaler. This suggests that the absorption from the lung is influenced by the fine particle dose. We concluded that DPI is a suitable inhaler for FK224, and the alveolus, which is generally known as the site of action of the fine particles, is a possible absorptive site for FK224.

Administration, Inhalation↗

Inhalation technique and variables associated with misuse of conventional metered-dose inhalers and newer dry powder inhalers in experienced adults.

BACKGROUND: Pressurized metered-dose inhalers (pMDIs) are often poorly used, but little information is available concerning use of the newer dry powder inhalers (DPIs). OBJECTIVE: To estimate the inhalation technique and variables associated with the misuse of pMDIs and newer DPIs in clinical practice. METHODS: A multicenter, observational survey was used to evaluate the inhalation technique in 1,404 experienced outpatients aged 15 to 88 years affected mostly by asthma (47%) and chronic obstructive pulmonary disease (39%). A total of 1,056 patients were using pMDIs, 190 in conjunction with a large volume spacer (LVS); regarding DPIs, 230 patients were using the Aerolizer Inhaler, 524 were using the Turbuhaler, and 475 were using the Diskus. In each center, a trained observer recorded patients' inhalation techniques for each inhaler used against a standardized step-by-step checklist. RESULTS: Twenty-four percent and 3% of patients used pMDIs poorly, alone or with an add-on LVS, respectively. Failure to correctly perform essential steps for reliable lung delivery with the Aerolizer Inhaler, Turbuhaler, and Diskus was found in 17%, 23%, and 24% of patients, respectively. There was no difference in most variables correlated with poor inhalation between patients using pMDIs and those using DPIs. CONCLUSIONS: The use of DPIs is associated with a similar percentage of inadequate inhalation technique as the use of pMDIs in clinical practice. The addition of an LVS to a pMDI and education from health care personnel, rather than simply changing inhalers, represent the best strategies for minimizing poor inhalation technique.

Administration, Inhalation↗

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.

Administration, Inhalation↗

Lower oropharyngeal deposition of inhaled ciclesonide via hydrofluoroalkane metered-dose inhaler compared with budesonide via chlorofluorocarbon metered-dose inhaler in healthy subjects.

OBJECTIVE: Inhaled corticosteroids may cause oropharyngeal side effects if deposited in the oropharynx in active form. Ciclesonide, an inhaled corticosteroid with low glucocorticoid receptor affinity, is activated primarily in the lung by esterases to an active metabolite, desisobutyryl-ciclesonide (des-CIC), with high glucocorticoid receptor affinity. We studied oropharyngeal deposition of ciclesonide, des-CIC, and budesonide. METHODS: In an open-label, randomized, two-treatment (administered in sequence), five-period study, 18 healthy subjects received 800 microg (ex-valve) inhaled ciclesonide via a hydrofluoroalkane-pressurized, metered-dose inhaler followed by 800 microg budesonide (Pulmicort) by a chlorofluorocarbon-pressurized, metered-dose inhaler (four puffs of 200 microg each, ex-valve) or vice versa. Oropharyngeal cavity rinsing was performed immediately, or 15, 30, 45, or 60 min after inhalation (one rinsing per study period), and the solutions were analyzed using liquid chromatography with tandem mass spectrometric detection. RESULTS: Ciclesonide and budesonide were detected in most oropharyngeal wash samples. Maximal concentration of each inhaled corticosteroid was reached immediately post-inhalation; maximal concentrations of ciclesonide and des-CIC were 30% and 0.67%, respectively, of budesonide. Oropharyngeal deposition of ciclesonide and budesonide decreased rapidly within 15 min post-inhalation, and less rapidly thereafter. Less than 10% of the residual ciclesonide in the oropharynx was converted to des-CIC. The molar dose-adjusted amount of des-CIC was 4% of budesonide (P < 0.0001). There were no significant adverse events. CONCLUSION: Oropharyngeal deposition of des-CIC was more than one order of magnitude lower than that of budesonide when administered by the respective metered-dose inhalers. This may explain the low frequency of oropharyngeal side effects of ciclesonide in clinical studies.

Administration, Inhalation↗

Combination of inhaled long-acting beta2-agonists and inhaled steroids versus higher dose of inhaled steroids in children and adults with persistent asthma.

BACKGROUND: In asthmatic patients inadequately controlled on inhaled corticosteroids and/or those with moderate persistent asthma, two main options are recommended: the combination of a long-acting inhaled beta2 agonist (LABA) with inhaled corticosteroids (ICS) or use of a higher dose of inhaled corticosteroids. OBJECTIVES: To determine, in asthmatic patients, the effect of the combination of long-acting beta2 agonists and inhaled corticosteroids compared to a higher dose of inhaled corticosteroids on the incidence of asthma exacerbations, on pulmonary function and on other measures of asthma control and to look for characteristics associated with greater benefit for either treatment option. SEARCH STRATEGY: We identified randomized controlled trials (RCTs) through electronic database searches (MEDLINE, EMBASE and CINAHL), bibliographies of RCTs and correspondence with manufacturers until April 2004. SELECTION CRITERIA: RCTs were included that compared the combination of inhaled LABA and ICS to a higher dose of inhaled corticosteroids, in children aged 2 years and older, and in adults with asthma. DATA COLLECTION AND ANALYSIS: Studies were assessed independently by two authors for methodological quality and data extraction. Confirmation was obtained from the trialists when possible. The primary endpoint was rate of patients experiencing one or more asthma exacerbations requiring oral corticosteroids. Secondary endpoints included pulmonary function tests (PFTs), symptoms, use of rescue beta2 agonists, adverse events and withdrawal rates. The meta-analysis was done with RevMan Analyses and the meta-regression, with Stata. MAIN RESULTS: Of 593 citations identified, 30 (three pediatric; 27 adult) trials were analysed recruiting 9509 participants, including one study providing two control-intervention comparisons. Only one trial included corticosteroid-naive patients. Participants were symptomatic, generally (N=20 trials) presenting with moderate (FEV1 60-79% of predicted) rather than mild airway obstruction. Trials tested the combination of salmeterol (N=22) or formoterol (N=8) with a median of 400 mcg of beclomethasone or equivalent (BDP-eq) compared to a median of 800 to 1000 mcg/day of BDP-eq. Trial duration was 24 weeks or less in all but four trials. There was no significant group difference in the rate of patients with exacerbations requiring systemic corticosteroids [N=15, RR=0.88 (95% CI: 0.77, 1.02)]. The combination of LABA and ICS resulted in greater improvement from baseline in FEV1 [N=7, WMD=0.10 L (95% CI: 0.07, 0.12)], in symptom-free days [N=8 , WMD=11.90% (95% CI:7.37, 16.44), random effects model], and in the daytime use of rescue beta2 agonists than a higher dose of ICS [N=4, WMD= -0.99 puffs/day (95% CI: -1.41, -0.58), random effects model]. There was no significant group difference in the rate of overall adverse events [N=15, RR=0.93 (95% CI: 0.84, 1.03), random effects model], or specific side effects, with the exception of a three-fold increase rate of tremor in the LABA group [N= 10, RR=2.96 (95%CI: 1.60, 5.45)]. The rate of withdrawals due to poor asthma control favoured the combination of LABA and ICS [N=20, RR=0.69 (95%CI: 0.52, 0.93)]. AUTHORS' CONCLUSIONS: In adult asthmatics, there was no significant difference between the combination of LABA and ICS and a higher dose of ICS for the prevention of exacerbations requiring systemic corticosteroids. Overall, the combination therapy led to greater improvement in lung function, symptoms and use of rescue beta2 agonists, (although most of the results are from trials of up to 24 weeks duration). There were less withdrawals due to poor asthma control in this group than when using a higher dose of inhaled corticosteroids. Apart from an increased rate of tremor, the two options appear safe although adverse effects associated with long-term ICS treatment were seldom monitored.

Administration, Inhalation↗

The relative bioavailability of salbutamol to the lung using urinary excretion following inhalation from a novel dry powder inhaler: the effect of inhalation rate and formulation.

Each dry powder inhaler has a different resistance so that a respirable dose can be generated from the formulation by the patient's inspiratory effort. It is important to recognize that this effect is achievable. The inspiratory flow characteristics of asthmatics inhaling through a Clickhaler were determined. In a separate study 10 volunteers inhaled separate 2 x 100 microg salbutamol doses from a Clickhaler (ML Laboratories plc U.K.). Two different formulations (one with a high and one with a low respirable fraction) were each inhaled using an inspiratory flow of 30 and 60 l min(-1). A urine sample was collected 30 min post inhalation and then pooled for the next 24 h. The mean (SD) inhalation rate of 24 asthmatics when they inhaled from a Clickhaler was 37.3 (14.6) l min(-1). The mean (SD) urinary salbutamol excretion during the first 30 min, by the volunteers, using the high respirable dose formulation at 30 and 60 l min(-1) was 5.59 (1.87) and 4.62 (1.49) microg respectively (P<0.01). Similar values using the low respirable dose formulation were 4.84 (1.58) and 3.86 (2.14) microg. There was no significant difference between the amounts excreted in the 24 h post-dose. The different 30-min urinary excretions following inhalation of the two formulations suggest a link between the relative bioavailability of salbutamol to the lung and the respirable dose, and that a slow inhalation rate should be used when using a Clickhaler. The patient study shows that this rate is achieved by most asthmatics without further training.

Administration, Inhalation↗

Deposition of corticosteroid aerosol in the human lung by Respimat Soft Mist inhaler compared to deposition by metered dose inhaler or by Turbuhaler dry powder inhaler.

Fourteen mild-to-moderate asthmatic patients completed a randomized four-way crossover scintigraphic study to determine the lung deposition of 200 microg budesonide inhaled from a Respimat Soft Mist Inhaler (Respimat SMI), 200 microg budesonide inhaled from a Turbuhaler dry powder inhaler (Turbuhaler DPI, used with fast and slow peak inhaled flow rates), and 250 microg beclomethasone dipropionate inhaled from a pressurized metered dose inhaler (Becloforte pMDI). Mean (range) whole lung deposition of drug from the Respimat SMI (51.6 [46-57]% of the metered dose) was significantly (p < 0.001) greater than that from the Turbuhaler DPI used with both fast and slow inhaled flow rates (28.5 [24-33]% and 17.8 [14-22]%, respectively) or from the Becloforte pMDI (8.9 [6-12]%). The deposition pattern within the lungs was more peripheral for Respimat SMI than for Turbuhaler DPI. The results of this study showed that Respimat SMI deposited corticosteroid more efficiently in the lungs than either of two widely used inhaler devices, Turbuhaler DPI or Becloforte pMDI.

Adult↗

Absolute oral versus inhaled bioavailability: significance for inhaled drugs with special reference to inhaled glucocorticoids.

Orally inhaled drugs provide great benefit in the treatment of asthma as they are delivered directly to the site of action, i.e. the lung. The absolute oral inhaled bioavailability of a glucocorticoid results from the combination of the bioavailability of the dose delivered to the lung and the bioavailability of the dose delivered into the gastrointestinal (GI) tract. The majority of the dose delivered to the lung is absorbed and available systemically. For the portion of the glucocorticoid dose delivered orally, bioavailability depends upon absorption from the GI tract and the extent of first pass/pre-systemic metabolism in the GI tissue and liver. Since this oral component of the delivered dose does not provide any beneficial therapeutic effect but can contribute to the systemic side effects, it is desirable for the absolute oral bioavailability of inhaled glucocorticoids to be relatively low (which is the case with most of the glucocorticoids, < 25%). Another approach to limiting systemic exposure from inhaled delivery is to improve the effectiveness of the oral inhaled formulation and delivery device, by increasing the fraction of the total inhaled dose which reaches the lung. Since current inhalation technology can provide respirable fractions in the range of 30-50%, what is the significance of the oral component of systemic exposure in relation to the overall systemic exposure following the oral inhalation administration of glucocorticoids? Below a certain point (approximately 25%), lower oral bioavailability of inhaled drugs may not be clinically important with respect to systemic exposure if the lung targeting is good (30%).

Administration, Inhalation↗

Relative lung and total systemic bioavailability following inhalation from a metered dose inhaler compared with a metered dose inhaler attached to a large volume plastic spacer and a jet nebuliser.

OBJECTIVE: To compare the lung and systemic delivery of salbutamol following inhalation from a metered dose inhaler (MDI), a MDI attached to a spacer (MDI+SP) and a nebuliser (NEB) using a urinary pharmacokinetic method. METHOD: Twelve healthy subjects each provided urine samples at 0, 30 min and pooled up to 24 h after the start of 5 x 100 microg salbutamol inhaled from MDI and MDI + SP and after 2.5 mg was delivered by NEB. Following nebulisation, the amount of salbutamol trapped on an exhalation filter together with that remaining in the apparatus was determined. The amount left in the spacer and that leaving the MDI mouthpiece was also determined. Thus, for all the methods, the amount available for inhalation from each study dose was determined. RESULTS: The mean (+/- SD) 30-min urinary excretion amounts of salbutamol for MDI, MDI+SP and NEB were 12.6+/-3.5, 27.1+/-6.0 and 16.1+/-4.6 microg, respectively. The mean ratios (90% confidence intervals) for MDI+SP compared with MDI and NEB were 230.2 (186.7, 273.8) and 183.0 (146.4, 219.7) (both P values<0.001), respectively, while that between MDI and NEB was 134 (110.4, 159.1) (P < 0.05). The mean (+/-SD) 24-h urinary excretion values for salbutamol and its metabolite were 287.0+/-46.5, 198.1+/-34.7 and 253.4+/-138.3 microg, respectively. Following inhalation a mean of 202.9+/-51.5 microg was left in the spacer. Similarly, after nebulisation 1387.7+/-88.9 microg was left in the nebuliser chamber, 26.3+/-8.0 microg in the mouthpiece and 553.8+/-68.5 microg exhaled. The mean emitted dose from the MDI was 88.4+/-6.1 microg per actuation. When normalised for the amounts available for inhalation, the mean amounts of salbutamol excreted in the urine during the first 30 min were 2.86+/-0.78, 9.15+/-1.69 and 3.06+/-0.70% following MDI, MDI + SP and NEB, respectively. CONCLUSION: Five 100-microg doses inhaled from a metered dose inhaler attached to a spacer delivered more to the lungs and less to the systemic circulation than either the same doses from a metered dose inhaler used alone or five times the dose given via a jet nebuliser. Spacers should be routinely used instead of nebulisers to manage patients unless they are short of breath.

Adult↗

Effects, side effects and plasma concentrations of terbutaline in adult asthmatics after inhaling from a dry powder inhaler device at different inhalation flows and volumes.

1. The efficacy of a metered dose inhaler (MDI) is highly dependent on the mode of inhalation. The relatively high built-in resistance in the Turbohaler (TBH), a new dry powder inhaler device for inhalation of terbutaline sulphate and budesonide, reduces the flow during inhalation. We compared five different modes of inhalation using the terbutaline TBH in 10 stable asthmatic subjects, who were tested on 5 consecutive days. 2. Measurement of 10 different parameters of pulmonary function indicated that the full bronchodilatory effect of an inhaled dose was already achieved at 5 min after the inhalation. Inspiratory flows through the TBH varying from 34 to 88 l min-1 resulted in comparable bronchodilation, and a previous exhalation to residual volume proved of no value. However, if, prior to inhalation, an exhalation through the device was performed, a substantially reduced effect was seen. 3. Reducing the inspiratory flow to approximately 34 l min-1 produced slightly reduced side effects and lower plasma terbutaline concentrations.

Adult↗

Medical personnel's knowledge of and ability to use inhaling devices. Metered-dose inhalers, spacing chambers, and breath-actuated dry powder inhalers.

BACKGROUND: Current treatment strategies for asthma and chronic obstructive pulmonary disease (COPD) emphasize the inhalation route, yet patients often misuse metered-dose inhalers (MDI). To address this problem, patient education by medical personnel has been recommended and a variety of alternate inhaler devices have been developed. METHODS: We surveyed medical personnel to assess their knowledge of and ability to use three widely used inhaler devices; MDI, MDI with a spacing chamber (Aerochamber, Trudell Medical, Canada), and a breath-actuated multidose dry powder inhaler (Turbuhaler, Astra Pharmacy, Inc., Conada). Thirty respiratory therapists (RT), 30 registered nurses (RN), and 30 medical house staff physicians (MD) were asked to demonstrate the use of each device using placebo inhalers and to answer 11 clinically relevant questions related to the use and maintenance of the tested devices. RESULTS: The RT's percent mean knowledge score (67 +/- 5 percent) was significantly higher than those achieved by either the RNs (39 +/- 7 percent) or the MDs (48 +/- 7 percent) (for all p < 0.0001). Similarly, percent mean demonstration scores for each device were significantly higher for RTs than either RN or MD groups; for MDI, 97 +/- 3 percent versus 82 +/- 13 percent and 69 +/- 24 percent, respectively (p < 0.0001); for the Aerochamber, 98 +/- 2 percent versus 78 +/- 20 percent and 57 +/- 31 percent (p < 0.0001); and for the Turbuhaler, 60 +/- 30 percent versus 12 +/- 23 percent and 21 +/- 30 percent (p < 0.0001). Knowledge of and practical skills with the devices were roughly proportional to the length of time the device had been in clinical use, Turbuhaler demonstration scores being lower than either MDI or Aerochamber scores (p = 0.05 and p = 0.09, respectively). More RTs (77 percent) had received formal instruction on the use of devices at school than either RNs (30 percent) or MDS (43 percent) (p < 0.05). CONCLUSION: We conclude that (1) many medical personnel responsible for monitoring and instructing patients in optimal inhaler use lack rudimentary skills with these devices, (2) nurses and physicians seldom receive formal training in the use of inhaling devices, and (3) newer inhaling devices designed to obviate problems of technique are at present less likely to be used well by medical personnel soon after their introduction.

Clinical Competence↗