Cumulative dose-response study of non-CFC propellant HFA 134a salbutamol sulfate metered-dose inhaler in patients with asthma

Bronchodilator Dose Responsiveness in Children and Adolescents: Clinical Features and Association with Future Asthma Exacerbations

BACKGROUND

Bronchodilator reversibility measures are often associated with poor asthma outcomes in children. Whether bronchodilator dose responsiveness is similarly useful in children is unclear.

OBJECTIVE

We hypothesized that children and adolescents requiring higher doses of bronchodilator to achieve maximal bronchodilation would have unique risk factors and increased risk of future exacerbation.

METHODS

Children (6-11 years, N = 299) and adolescents (12-21 years, N = 331) with confirmed asthma underwent clinical phenotyping procedures and a test of maximal bronchodilation with escalating doses of albuterol sulfate up to 720 mcg. Outcome measures were assessed at 12 months and included exacerbations treated with systemic corticosteroids, emergency department (ED) visits, and hospitalizations for asthma.

RESULTS

A total of 6.7% of children and 9.3% of adolescents had poor bronchodilator dose responsiveness, defined as attainment of maximal forced expiratory volume in 1 second with 720 mcg albuterol. Risk factors included type 2 inflammation, prior exacerbations, and greater asthma severity; historical pneumonia and tobacco exposure were also risk factors in children. Children and adolescents with poor bronchodilator dose responsiveness did not have increased current symptoms or impaired quality of life, but had approximately 2-fold increased odds of exacerbation or ED visit and approximately 3-fold increased odds of hospitalization by 12 months, independent of airflow obstruction.

CONCLUSIONS

Bronchodilator dose responsiveness may be useful for phenotyping and may be of utility in practice and future studies focused on asthma outcomes or quantification of treatment responses. In children and adolescents, this phenotype of poor bronchodilator responsiveness may be associated with periods of relatively stable disease yet marked airway constriction in response to triggers, including tobacco smoke, respiratory infections/pneumonia, and aeroallergens.

Albuterol HFA for the management of obstructive airway disease

Albuterol (salbutamol outside the USA) is used to acutely relieve symptoms related to airway obstruction and prevent exercise-induced bronchospasm. Albuterol is most commonly administered by metered-dose inhaler (MDI). MDIs had used chlorofluorocarbon (CFC) propellants, but CFCs accumulate in the stratosphere and contribute to ozone catabolism. Loss of the 'ozone layer', which filters UVB rays, has public health concerns. Albuterol has been reformulated in MDIs using hydrofluoroalkane (HFA) propellants, which do not affect the ozone layer. Albuterol HFA MDIs deliver the same amount of drug per puff with similar particle size distributions as albuterol CFC MDIs, resulting in comparable bronchodilator efficacy of the two products. The highly favorable safety profile of albuterol has not been altered with reformulation. The propellant HFA-134a appears to be devoid of safety concerns.

Effects of fluticasone propionate and salmeterol hydrofluoroalkane inhalation aerosol on asthma-related quality of life

BACKGROUND

Current asthma guidelines emphasize domains of impairment and risk for assessing severity and control, noting the need to consider separately the effects of asthma on asthma quality of life and functional capacity. Proper treatment to control asthma should result in improvements in patient well-being and functional status.

OBJECTIVE

To assess asthma-related quality of life after treatment with combination fluticasone propionate and salmeterol delivered via hydrofluoroalkane 134a metered-dose inhaler compared with the individual components alone.

METHODS

Asthma-related quality of life was assessed as part of two 12-week, randomized, double-blind, placebo-controlled clinical trials comparing the fluticasone propionate-salmeterol combination administered via a single metered-dose inhaler with salmeterol, fluticasone propionate, and placebo administered via traditional chlorofluorocarbon metered-dose inhaler. The Asthma Quality of Life Questionnaire was completed at baseline and end point. Score changes, overall and for the 4 separate domains, were compared within and among the treatment groups.

RESULTS

A total of 720 of 725 patients completed a baseline Asthma Quality of Life Questionnaire and were included in the analyses. In both studies, all mean scores improved significantly from baseline with the fluticasone propionate-salmeterol combination, with significantly greater improvement in the overall score compared with salmeterol alone, fluticasone propionate alone, and placebo groups. Improvements with the combination were also clinically meaningful compared with changes with salmeterol and placebo in both studies and with fluticasone propionate in study 1.

CONCLUSIONS

Treatment with combination fluticasone propionate and salmeterol delivered via hydrofluoroalkane metered-dose inhaler resulted in significantly greater improvements in asthma-related quality of life compared with individual components and placebo administered via traditional chlorofluorocarbon metered-dose inhaler.

How best to deliver aerosol medications to mechanically ventilated patients

Pressurized metered-dose inhalers (pMDIs) and nebulizers are employed routinely for aerosol delivery to ventilator-supported patients, but the ventilator circuit and artificial airway previously were thought to be major barriers to effective delivery of aerosols to patients receiving mechanical ventilation. In the past two decades, several investigators have shown that careful attention to many factors, such as the position of the patient, the type of aerosol generator and its configuration in the ventilator circuit, aerosol particle size, artificial airway, conditions in the ventilator circuit, and ventilatory parameters, is necessary to optimize aerosol delivery during mechanical ventilation. The best techniques for aerosol delivery during noninvasive positive-pressure ventilation are not well established as yet, and the efficiency of aerosol delivery in this setting is lower than that during invasive mechanical ventilation. The most efficient methods of using the newer hydrofluoroalkane-pMDIs and vibrating mesh nebulizers in ventilator-supported patients also require further evaluation. When optimal techniques of administration are employed, the efficiency of aerosolized drug delivery in mechanically ventilated patients is comparable to that achieved in ambulatory patients.

Access to inhaled corticosteroids is key to improving quality of care for asthma in developing countries

Asthma is a worldwide public health problem affecting about 300 million people. The majority of persons living with asthma are in the developing world where there is limited access to essential drugs. The financial burden for persons living with asthma and their families, as well as for healthcare systems and governments, is very high. Inadequate treatment and the high cost of medications leads to disability, absenteeism and poverty. Despite the existence of effective asthma medications and international guidelines, and progress made in the implementation of such guidelines over the last decade, the high cost of essential asthma medications remains a major obstacle for patient access to treatment in developing countries. The International Union Against Tuberculosis and Lung Disease has evaluated this problem and created an Asthma Drug Facility (ADF) so that countries can purchase affordable, good quality essential drugs for asthma. The ADF uses pooled procurement along with other purchasing and supply strategies to obtain the lowest possible prices. Accompanied by the implementation of standardized asthma management, the increased affordability of drugs provided by the ADF should bring rapid and significant health and cost benefits for patients, their communities and governments.

Propellant-driven metered-dose inhalers for pulmonary drug delivery

The current market for pulmonary drug delivery is at a bottleneck. The therapeutic advantages of inhalation aerosols, and the potential for the lungs as a route for systemically acting drugs, vaccines and gene therapeutic agents, have resulted in a rapid growth of the industry. Alongside this, the environment of inhaler design and formulation has changed markedly in recent years. Environmental concerns over propellants, the commercial success of dry powder inhalers, and the apparent lack of advancement of propellant-driven metered-dose inhalers (pMDIs) has led to a less clear future for these devices. This review critically assesses these pressures and also potential opportunities for the pMDI. It is proposed that the future role of pMDIs will be determined by several important forces that can be classified under 'technology development' or 'market climate' categories. Technology development forces will be strengthened by the ability of the industry to have a systematic understanding of mechanisms of spray formation, perform subsequent and continued device and formulation advances, and a focus on all patient groups: particularly paediatric and geriatric populations. The ability to succeed in these areas will be largely determined by the willingness to invest in fundamental research of pMDI technologies.

An investigation into the predictive value of cascade impactor results for side effects of inhaled salbutamol

The aim of this study was to compare the Multistage Liquid Impinger (MSLI) and the Andersen Cascade Impactor (ACI) with respect to their power to predict differences in side effects of salbutamol delivered by a dry powder inhaler. Three preparations with the same nominal dose and the same inhaler device but generating aerosols with different aerodynamic particle size distributions were administered to six healthy volunteers in a randomized, placebo-controlled, four-way crossover study. Cumulative doses from 400 up to 1600 microg were given. The serum potassium level (K+-serum) and the heart rate (HR) were measured at baseline and 15 min after each dose. Both the MSLI and ACI showed large differences between the aerodynamic particle size distributions of the three preparations. The decrease in K+-serum revealed significant differences between the three active preparations and was significant for doses of 800 microg and higher. The HR results showed differences between the active preparations only at a nominal dose of 1600 microg and only for the preparation with the highest fine particle dose (FPD) compared to the other two preparations. The K+-serum appears to be a more sensitive measure for side effects than the HR. In vivo-in vitro correlations (IVIVCs) were established between the amounts of salbutamol deposited on the various cumulative impactor stages and the K+-serum. The best IVIVCs were obtained in the FPD range, resulting in correlation coefficients of at least 0.78. It is concluded that cascade impactor results in the FPD range of the MSLI as well as the ACI correlate well with the K+-serum. Cascade impactor analysis thus provides a clinically meaningful tool in the development and the quality control of salbutamol inhalation powders.

Comparison of bronchoprotective and bronchodilator effects of a single dose of formoterol delivered by hydrofluoroalkane and chlorofluorocarbon aerosols and dry powder in a double blind, placebo-controlled, crossover study

BACKGROUND

In response to the phasing out of chlorofluorocarbon (CFC) inhalers, a metered dose hydrofluoroalkane (HFA) formulation, Modulite (Chiesi Farmaceutici S.p.A, Parma, Italy), to be delivered with a pressurized metered dose inhaler (pMDI), has been developed. Modulite is a HFA formulation technology that has been designed to provide stable and uniform dose delivery of HFA-based formulations to enable an easy transition from CFC to HFA inhalers.

OBJECTIVES

The aim of this study was to compare the bronchoprotective and bronchodilator effects of a single dose of 12 microg of formoterol from the HFA Modulite inhaler with the Foradil Aerolizer (dry powder inhaler, DPI) and the Foradil CFC inhalers (Novartis Health Consumer, Basel, Switzerland).

METHODS

This was a double blind, double dummy, randomized, placebo-controlled, crossover study conducted in 38 subjects with mild to moderate asthma (mean forced expiratory volume in 1 s [FEV1] 87.5% predicted). The primary endpoint was methacholine challenge provocative dose required for 20% fall in the FEV1 (PD20) 90 min post dose. Bronchodilation was assessed with spirometry (FEV1, FVC, FEF25-75) and impulse oscillometry (resistance at 5 and 20 Hz, reactance at 5 Hz and resonant frequency) over the 90 min post dose. In a subset of 12 subjects formoterol plasma levels, serum potassium and glucose were determined up to 480 min post dose.

RESULTS

The three formoterol formulations demonstrated significant (P < or = 0.05) improvements in bronchoprotection compared to placebo and non-inferiority of the HFA preparation compared to the CFC and DPI preparations was demonstrated. Geometric mean PD20 values were 0.51 mg with HFA, 0.62 mg with DPI, 0.62 mg with CFC and 0.2 mg with placebo. The log transformed mean differences in PD20 doubling dose between HFA and (a) DPI was -0.28 (95% CI -0.84-0.29, P = 0.57) (b) CFC was -0.28 (95% CI -0.84-0.28, P = 0.57) and (c) placebo was 1.38 (95% CI 0.82-1.94, P < 0.001). Serum potassium, glucose and formoterol plasma profiles were comparable for the CFC, HFA and DPI devices.

CONCLUSION

Our findings of similar efficacy, pharmacokinetics and systemic effects of the HFA formoterol inhaler compared to the CFC and DPI preparations supports the potential use of this novel formulation in the treatment of asthma.

Effect of mouthpiece washing on aerosol performance of CFC-free Ventolin

The prescribing information for chlorofluorocarbon (CFC)-free salbutamol metered-dose inhalers carries a strongly-worded instruction to wash the mouthpiece weekly, but patients rarely carry this out. This study investigated the effect of washing/not washing the mouthpiece on CFC-free Ventolin aerosol performance. Twelve CFC-free Ventolin inhalers were actuated two puffs four times/day, and assessed by unit dose sampler and cascade impactor on Days 1, 7, 8, 14, 15, 21, and 22 ("throughlife," i.e., over the entire content of the inhaler). The mouthpieces of six inhalers were washed after the last actuation on Days 7, 14, and 21. A single priming maneuver, as recommended by the manufacturer, was sufficient for fine particle mass. There were no significant through-life differences in delivered dose between washed and unwashed inhalers. Without washing, fine particle mass fell from 47 microg to 33 microg (Friedman p=0.002). Fine particle mass increased significantly after washing (median change + 11.2 microg, p=0.019 cf. unwashed). Large particle mass showed no significant through-life trend for washed or unwashed inhalers, but was significantly reduced after washing (p=0.04 cf. unwashed). This study shows a progressive through-life reduction in fine particle mass from CFC-free Ventolin inhalers, which is prevented by weekly mouthpiece washing. However, in view of the steep bronchodilator dose-response curve for salbutamol, further studies are needed to determine whether such device care is clinically necessary.

Clinical efficacy of inhaler devices containing beta(2)-agonist bronchodilators in the treatment of asthma: cochrane systematic review and meta-analysis of more than 100 randomized, controlled trials

BACKGROUND

A number of different inhaler devices are available to deliver beta(2)-adrenoceptor agonist (beta(2)-agonist) bronchodilators in asthma. These include hydrofluoroalkane or chlorofluorocarbon (CFC)-free propelled pressurized metered-dose inhalers (pMDIs), many dry powder inhalers and breath-actuated inhalers.

OBJECTIVE

To determine the clinical efficacy of all available hand-held inhaler devices compared with the standard CFC-containing pMDI for the delivery of short-acting beta(2)-agonist bronchodilators in nonacute asthma in both children and adults.

METHODOLOGY

A systematic review and meta-analysis was carried out of all available randomized, controlled trials (RCTs) using the standard pMDI compared with any other hand-held inhaler device, delivering short-acting beta(2)-agonist bronchodilators in patients with stable asthma.

RESULTS

One hundred and eighteen RCTs were included in this review. No clinical differences were found between the standard CFC-containing pMDI and 12 other hand-held inhaler devices for most outcome measures. We found no evidence of clinical differences between studies using either a 1 : 1 (pMDI: another inhaler) or a 2 : 1 dosing ratio.

CONCLUSIONS

In patients with stable asthma, short-acting beta(2)-agonist bronchodilators in standard CFC-pMDIs are as effective as any other hand-held inhaler device; therefore the cheapest available device that the patient is able to use should always be considered. Pharmaceutical companies should in future submit to regulatory authorities clinical outcome data (as opposed to in vitro data) in support of any dosing schedules greater than 1 : 1 when compared with the standard pMDI. Clinical effectiveness studies that use an intention-to-treat analysis and report more patient-centered outcomes are required.

Efficacy response of inhaled HFA-albuterol delivered via the breath-actuated Autohaler inhalation device is comparable to dose in patients with asthma

Handling difficulties, such as poor coordination of actuation and inhalation, are common in patients using press and breathe (P&Bs) metered-dose inhalers to administer asthma medication. Although spacers can help overcome some difficulties, the cumbersome nature of these devices often detracts from their use for the administration of rescue medications, where portability is important. This randomized, placebo-controlled, multicenter, crossover study investigated the efficacy, dose-response and safety of HFA-albuterol delivered via a breath-actuated Autohaler inhalation device in comparison with the same medication delivered using a conventional P&B device. In total, 39 patients received six study treatments in a random sequence at clinic visits separated by 2-7 days: 2 puffs from a HFA-placebo Autohaler; 1, 2, or 4 puffs from a HFA-albuterol Autohaler; I or 2 puffs from a HFA-albuterol P&B. Both active inhalers delivered 90 microg albuterol base equivalent/actuation from the actuator. The change from baseline in forced expiratory volume in 1 s (FEV1) and the area under the FEV1 curve (FEV1 AUC) were significantly greater than placebo for all active treatment groups (p < or = 0.01) and were suggestive of a dose response for each inhaler. Examination of the pooled slope of the dose responses for the Autohaler and P&B using Finney's Parallel Line Bioassay Methodology found a highly statistically significant relationship indicating the equivalence of the two inhalers on both parameters (p < or = 0.002). The relative potency of the two inhalers was 0.8 (95% CI: 0.47, 1.46) for the mean change from baseline in FEV1 and 0.9 (95% CI, 0.56, 1.48) for the change from baseline in FEV1 AUC. There was also a trend toward an increase in the mean percentage change from baseline in FEV1 as the number of puffs increased for both inhalers. Furthermore, there were no significant differences between the treatment groups with regard to time to onset of bronchodilator effect and the duration of effect was significantly greater than placebo (p < or = 0.01) in each of the active groups. Adverse events were generally mild to moderate in nature and were of similar incidence (< or = 18% of patients) in each group. This study demonstrates a dose-response for HFA-albuterol on bronchodilation using both the Autohaler and P&B devices and illustrates that, in patients with good coordination of inhalation with actuation, the efficacy and safety of the two inhalers is similar at equivalent doses.

The influence of inhaler selection on efficacy of asthma therapies

Many different devices are available to aid inhalational drug delivery. Although each device is claimed to have advantages over its rivals, the evidence to support greater efficacy of a particular device is scanty. Most comparative studies are underpowered or flawed in their design. They may use inappropriate end-points, or involve healthy subjects, whose response may be very different from the patient with acute severe asthma. The dosage of drug used in a trial may be at the shallow part of the dose-response curve, masking differences in devices. Only in a few cases have clinical trials detected a significant difference between devices, and trials have rarely taken patient preference into account. The most efficacious device in practice is likely to be the one that the patient will use regularly and in accordance with a health care workers' recommendations.

Effect of propellant on the pharmacokinetics and pharmacodynamics of inhaled albuterol in asthmatic subjects

Hydrofluoroalkane (HFA) propellants have largely replaced chlorofluorocarbon (CFC) propellants in metered dose inhalers (MDI). It is important to document the pharmacokinetics (PK) and pharmacodynamics (PD) of medications delivered using HFA propellants compared to CFC propellants. Six adult asthmatics with mild to moderate asthma were selected for the study. Each subject inhaled 180 microg of albuterol from an MDI with holding chamber. Venous blood was collected for measuring albuterol levels at intervals over 12 h, and spirometric measurements of airflow were measured over the same time period. Plasma samples were analyzed using a GC/MS assay developed in our laboratory. PK and PD parameters were calculated by nonlinear regression using WinNonlin. There were no statistically significant differences between PD parameters for HFA versus CFC propellants. The area under the plasma albuterol concentration versus time curve (AUC) was 72% greater for the HFA formulation, indicating a greater lung bioavailability (p = 0.015). This difference in bioavailability did not result in a statistically significant difference in FEV(1) values between the two propellants.

Pressurised metered dose inhalers versus all other hand-held inhaler devices to deliver beta-2 agonist bronchodilators for non-acute asthma

BACKGROUND

A number of different inhaler devices are available to deliver beta2-agonist bronchodilators in asthma. These include hydrofluoroalkane (HFA) or chlorofluorocarbon (CFC)-free propelled pressurised metered dose inhalers (pMDIs) and dry powder devices.

OBJECTIVES

To determine the clinical effectiveness of pMDI compared with any other available handheld inhaler device for the delivery of short-acting beta-2 agonist bronchodilators in non-acute asthma in children and adults.

SEARCH STRATEGY

The Cochrane Collaboration Clinical Trials register was searched for studies as well as separate additional searches carried out on MEDLINE, EMBASE, CINAHL and also on the Current Contents Index as well as the Science Citation Index. In addition, 17 individual online respiratory journals and 12 electronically available clinical trial databases were also searched. The UK pharmaceutical companies who manufacture inhaled asthma medication were contacted in order to obtain details of any published or unpublished studies.

SELECTION CRITERIA

- The full texts of all potentially relevant articles were reviewed independently by two reviewers.

DATA COLLECTION AND ANALYSIS

Fixed and random effect models were used. Dichotomous outcomes were assessed using Odds Ratios or Relative Risks (RR) with 95% Confidence Intervals (95%CI).

MAIN RESULTS

Eighty-four randomised controlled trials were included in this review, but few could be combined to assess a specific outcome for a given delivery device comparison. Only two studies required demonstration of adequate pMDI technique as an entry requirement. There were no difference between a standard CFC containing pMDI and any other device for most outcomes. Regular use of HFA-pMDI containing salbutamol reduced the requirement for short courses of oral corticosteroids (3 trials, 519 patients: RR 0.67; 95% CI 0.49, 0.91); however the total number of exacerbations were unchanged (3 trials, 1271 patients: RR 1.0; 95% CI 0.75, 1.33).

REVIEWER'S CONCLUSIONS

In patients with stable asthma, short-acting beta-2 bronchodilators in standard CFC-pMDI's are as effective as any other devices. The effect of HFA-pMDI on requirement for oral corticosteroid courses to treat acute exacerbations should be confirmed. Effectiveness studies that use an intention-to-treat analysis are required.

Systematic review of clinical effectiveness of pressurised metered dose inhalers versus other hand held inhaler devices for delivering beta (2 )agonists bronchodilators in asthma

OBJECTIVES

To determine the clinical effectiveness of pressurised metered dose inhalers compared with other hand held inhaler devices for delivering short acting beta(2) agonists in stable asthma.

DESIGN

Systematic review of randomised controlled trials.

DATA SOURCES

Cochrane Airways Group specialised trials database (which includes hand searching of 20 relevant journals), Medline, Embase, Cochrane controlled clinical trials register, pharmaceutical companies, and bibliographies of included trials.

TRIALS

All trials in children or adults with stable asthma that compared the pressurised metered dose inhaler (with or without a spacer device) against any other hand held inhaler device containing the same beta(2) agonist.

RESULTS

84 randomised controlled trials were included. No differences were found between the pressurised metered dose inhaler and any other hand held inhaler device for lung function, blood pressure, symptoms, bronchial hyperreactivity, systemic bioavailability, inhaled steroid requirement, serum potassium concentration, and use of additional relief bronchodilators. In adults, pulse rate was lower in those using the pressurised metered dose inhaler compared with those using Turbohaler (standardised mean difference 0.44, 95% confidence interval 0.05 to 0.84); patients preferred the pressurised metered dose inhaler to the Rotahaler (relative risk 0.53, 95% confidence interval 0.36 to 0.78); hydrofluoroalkane pressurised metered dose inhalers reduced the requirement for rescue short course oral steroids (relative risk 0.67, 0.49 to 0.91).

CONCLUSIONS

No evidence was found to show that alternative inhaler devices are more effective than standard pressurised metered dose inhalers for delivering acting beta(2 )agonist bronchodilators in asthma. Pressurised metered dose inhalers remain the most cost effective delivery devices.

Cumulative and single-dose design to assess the bronchodilator effects of beta2-agonists in individuals with asthma

With the development of different chlorofluorocarbon (CFC)-free metered dose aerosol and dry powder devices, it is necessary to study and validate the methods used for assessing and comparing their efficacy. This study evaluated the cumulative dose design by determining the bronchodilator response to salbutamol given according to either a high or a low cumulative dose regimen. Adults with asthma (n = 24) were studied in a placebo-controlled, randomized, double-blind, cross-over design. On separate days, cumulative doses of salbutamol (50+50+100+200 or 100+100+ 200+400 or 400+0+0+0 or 0+0+0+0 microg) were given via Turbuhaler with 30 min between doses. The two cumulative dose regimens produced almost identical bronchodilator responses at each time point. The relative dose-potency between the 800- and 400- microg cumulative dose regimens was 0.7 with a 95% confidence interval of 0.5-1.0, excluding the true value of 2. The 400-microg cumulative dose regimen resulted in a higher FEV1 at 115 min than the 400-microg single-dose regimen. There was no difference in the bronchodilator response to the single dose of 50, 100, or 400 microg of salbutamol after either 5 or 25 min. Thus, care should be exercised when using either a cumulative or single-dose design for comparing different beta2-agonists, or different inhalation devices, with respect to their relative dose-potency. In addition, this study provides further evidence that for short-acting beta2-agonists such as salbutamol, lower doses than those normally recommended may be used, and that repeated self-administration of low doses over a period of 60 min may give a better bronchodilator response than a single administration of a high dose.

Comparable bronchodilation with hydrofluoroalkane-134a (HFA) albuterol and chlorofluorocarbons-11/12 (CFC) albuterol in children with asthma

This was an open-label, parallel group, randomized, age-stratified, multicenter study designed to compare the safety and efficacy of regular use of albuterol formulated in hydrofluoroalkane-134a (HFA albuterol) and albuterol formulated in chlorofluorocarbons-11/12 (CFC albuterol) in children with asthma. Children age 4-11 years using a short-acting inhaled beta2-agonist for 6 months to manage stable asthma, and with a prestudy forced expiratory volume in 1 sec (FEV1) of >50% predicted after withholding short-acting inhaled beta2-agonists for at least 6 hr, an increase in FEV1 > or = 12% within 30 min after two puffs of CFC albuterol, and the capability to comply with medication withholding requirements were eligible for study entry. After screening evaluation, patients entered a minimum 7-day run-in period. On study day 1 spirometry and a baseline 12-lead electrocardiogram (ECG) were performed, pulse and blood pressure were measured, and patients self-administered two puffs of their randomized study drug, either HFA albuterol or CFC albuterol. Serial spirometry was performed over 6 hr after study drug dosing. Pulse and blood pressure were measured just prior to each spirometry and a 12-lead ECG was performed at 60 min postdose. Patients took two puffs of their study drug four times a day for 4 weeks. At study week 4, study day 1 procedures were repeated. Patients maintained a daily diary of morning (A.M.) and evening (P.M.) peak expiratory flow (PEF), daytime asthma symptom scores, nighttime asthma sleep disturbance scores, and study drug use. Demographics and baseline characteristics of the 63 patients randomized to HFA albuterol (33) and CFC albuterol (30) were similar. No significant differences were found between the HFA albuterol and CFC albuterol treatment groups for any of the primary or secondary FEV1 efficacy variables either at study day 1 or study week 4. No significant differences were noted between treatment groups for A.M. and P.M. PEF, individual asthma symptom scores, nighttime asthma sleep disturbance scores, and rescue study drug use over the 4-week study. No significant differences were found between the two treatment groups for change from predose in heart rate, systolic and diastolic blood pressure, and 12-lead ECG intervals at either study day 1 or study week 4. Adverse event reporting was similar for the two treatment groups. In this study, with regular use of HFA albuterol in children with asthma, there was a similar safety profile and comparable bronchodilator efficacy as with CFC albuterol.

Human lung deposition data: the bridge between in vitro and clinical evaluations for inhaled drug products?

Regulatory dossiers for new inhaled drug products generally contain in vitro data, which assess delivered dose and particle size distribution, together with clinical efficacy and safety data. Human lung deposition data may be generated using radionuclide imaging techniques or appropriate pharmacokinetic methods, and can act as a 'bridge' via which a seamless transition can be made between in vitro testing in the laboratory and efficacy/safety testing in the clinic. By enabling informed decisions to be made about the evaluation of new devices or formulations in man, lung deposition data permit a long and expensive clinical trials programme to be commenced with much greater certainty of a successful outcome. Human lung deposition data should be considered for supplementing the information required for regulatory dossiers.

Salbutamol via Easyhaler is at least as effective as salbutamol via Turbuhaler in the treatment of histamine-induced bronchoconstriction

The aim of this study was to compare the clinical efficacy and acceptability of salbutamol inhaled via Easyhaler and Turbuhaler multi-dose dry powder inhalers in the treatment of histamine-induced bronchoconstriction. Thirty-two adult patients with asthma and/or bronchial hyper-reactivity were included in the study, which was carried out according to a randomized, double-blind, double-dummy, cross-over design. Histamine challenge test was performed on 2 study days separated by at least 7 days. The challenge test was continued until a > or = 20% fall in forced expiratory volume in 1 sec (FEV1) was achieved. The patients then inhaled a single 100 microg dose of salbutamol from Easyhaler, or from Turbuhaler. FEV1 was assessed by flow-volume spirometry before and after histamine challenge and 1.5, 3, 5, 10, 15, 20, 30 and 60 min after salbutamol inhalation. The primary efficacy variable was the maximum percentage change in FEV1 from the post-challenge value. The secondary efficacy variable was area under the curve (AUC) of FEV1. At the end of the study, acceptability of salbutamol Easyhaler was evaluated using a questionnaire and Easyhaler was also compared with the inhalation device the patient had used earlier. Twenty-six patients completed the study. Both salbutamol Easyhaler and salbutamol Turbuhaler produced a rapid and significant increase in FEV1, with maximum percentage changes being 43.9% (+/-15.3) and 40.5% (+/-21.9) from the post-challenge value, respectively. There were no significant differences between the two inhalation devices in terms of changes in FEV1 or AUC of FEV1. The use of Easyhaler and getting a new dose from Easyhaler was considered to be very easy by 65% and easy by 35% of the patients. None considered it difficult. Of 16 patients who had used Turbuhaler earlier, 19% considered Easyhaler much better, 44% better, and 38% the same as Turbuhaler, and none considered it worse. In conclusion, the results show that salbutamol Easyhaler was at least as effective as salbutamol Turbuhaler in the treatment of histamine-induced bronchoconstriction. In addition, the patients considered Easyhaler very easy or easy to use. The majority of patients who reported Turbuhaler as their own inhaler considered Easyhaler better or much better than Turbuhaler.

Pharmacokinetics, pharmacodynamics, and the delivery of pediatric bronchodilator therapy

beta(2)-adrenergic receptor agonists have long been used for the amelioration of acute asthma symptoms and in the prophylactic treatment of exercise-induced asthma in both adults and children. To maximize the amount of drug that reaches the airways, small doses of the drug can be inhaled in aerosol form that preferentially activate pulmonary beta(2)-receptors, thereby reducing systemic absorption and adverse effects. Potential adverse effects of beta(2)-agonists include tremor, increased heart rate, and metabolic imbalances. Because of its specialized nature, aerosolized delivery to the airways has many additional variables that can alter the pharmacokinetics and pharmacodynamics of the administered drug.

Dose-response evaluation of levalbuterol versus racemic albuterol in patients with asthma

Albuterol, in all marketed forms, is sold as a racemate, composed of a 50:50 mixture of (R)- and (S)-isomers. Racemic albuterol and the single isomer version (R)-albuterol (levalbuterol) were compared in a randomized, double-blind, dose-ranging five-way crossover study in patients (n = 20) with mild persistent to moderate persistent asthma. Placebo, racemic albuterol (2.50 mg), or levalbuterol (0.31, 0.63, or 1.25 mg) were delivered as single, nebulized doses to 5 male and 15 female nonsmoking patients with asthma aged 18-50 years. Serial pulmonary function was assessed at 15-min intervals and mean time to onset of activity and duration of improvement of forced expiratory volume in 1 sec (FEV1) were measured. In addition, blood chemistries, electrocardiogram (ECG) readings, and patient subjective assessment of adverse symptoms were recorded. Levalbuterol was found to provide significant bronchodilatory activity and was well tolerated. Levalbuterol 1.25 mg provided the greatest increase and duration in FEV1 improvement, whereas racemic albuterol (2.50 mg) and levalbuterol 0.63 mg provided comparable effects. The lower doses of levalbuterol were associated with a less marked effect on heart rate and potassium than racemic albuterol or high-dose levalbuterol. These data suggest that 0.63 mg levalbuterol provides bronchodilation equivalent to 2.50 mg racemic albuterol with less beta-mediated side effects.

Aerosol therapy for asthma

Inhaled drugs play an important role in asthma management. The correct use of an appropriate delivery device is necessary to achieve the desired therapeutic effects of the drug. Currently, chlorofluorocarbon-propelled metered-dose inhalers, with or without spacers, are the most popular aerosol delivery devices. With the planned phase out of the chlorofluorocarbon metered-dose inhalers, the use of other delivery devices is being emphasized. To achieve optimal therapeutic effects, the drug and the delivery device should be considered a "couple". Aerosol delivery devices should provide an adequate "drug dose to the lung", be cost effective, simple to operate, minimize oropharyngeal deposition and systemic side effects, and match the patient's requirements. A new generation of aerosol delivery devices, incorporating the latest advances in aerosol technology, is likely to fulfill many of the goals mentioned above.

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.

Therapeutic equivalence of Spiros dry powder inhaler and Ventolin metered dose inhaler. A bioassay using methacholine

Because chlorofluorocarbons (CFCs) contribute to depletion of stratospheric ozone, CFC-containing metered-dose inhalers (MDIs) such as Ventolin and Proventil are being phased out of production. In terms of delivery of albuterol to the lungs, we compared an alternative delivery system, the Spiros dry-powder inhaler (DPI), with Ventolin, using a methacholine challenge-based clinical bioassay. Twenty-four adults and adolescents with asthma completed this double-blind, four-period crossover study. Doses evaluated were one and three actuations each of Spiros and Ventolin (90- and 270-microgram albuterol base). A methacholine challenge (Cockcroft method) was initiated 3 h before and 0.25 h after albuterol. Predose PC(20)FEV(1) values were not significantly different between study days. Postdose PC(20)FEV(1) results met standard bioassay study validity criteria: i.e., a significant dose-response relationship was present (p = 0.0002); tests for deviation from parallelism and overlap of dose-response curves were nonsignificant (p = 0.08, 0.69). By using Finney 2-by-2 bioassay analysis, we estimate that each Spiros actuation delivers 1.12 times as much albuterol to the airways as one Ventolin actuation (90% confidence interval, 0.68 to 1.94). There were no significant differences in markers of systemic effects (vital signs, potassium, and blood glucose concentrations). We conclude that Spiros and Ventolin inhalers deliver comparable quantities of albuterol to the airways.

Protection against methacholine bronchoconstriction to assess relative potency of inhaled beta2-agonist

The purposes of this study were to estimate the relative dose potency (RP) of two formulations of salbutamol pressurized metered-dose inhalers (Proventil-HFA and Ventolin-CFC MDIs) to protect against methacholine bronchoconstriction, to validate this method and provide recommendations. The protective effects of 100-, 200-, and 400-micrograms doses of Proventil-HFA were compared with the same doses of Ventolin-CFC in 18 adult asthmatics (mean FEV1, 92% predicted; mean baseline PC20 methacholine, 1.8 mg/ml), in a dose-level blind, balanced, eight-period, crossover, placebo-controlled study. The log-transformed PC20 values after each dose of the drugs were compared by repeated-measures analysis of variance (ANOVA). A significant dose-effect was present (p < 0.0001). Using the Finney assay, the RP of Proventil-HFA compared with Ventolin-CFC was 1.08 (90% CI, 0.81-1.46) (80% power). This was also estimated using a nonlinear Emax model to validate the Finney method. The most precise estimate of RP was obtained with the comparison between 100- and 200-micrograms doses (RP, 1.00; 90% CI, 0.77-1.31). There were no adverse events resulting from the drugs or methacholine. We conclude that Proventil-HFA salbutamol is bioequivalent to Ventolin-CFC salbutamol. Bronchoprotection to methacholine is a valid method of demonstrating bioequivalence. By this method, 100- and 200-micrograms doses of salbutamol inhalations from an MDI will suffice.

Inhaled beclomethasone (BDP) with non-CFC propellant (HFA 134a) is equivalent to BDP-CFC for the treatment of asthma

As part of a development programme for a range of new CFC-free beclomethasone dipropionate (BDP) inhalers, two multicentre double-blind studies have been conducted to compare the therapeutic equivalence of a new HFA-134a propellant-formulated BDP metered-dose inhaler (Norton Healthcare Ltd, London, U.K.) with a CFC counterpart for the management of adult patients with all grades of asthma. Doses of 100 micrograms qds for 6 weeks were administered in a low dose study and in a high dose study 500 micrograms qds doses were given for 12 weeks. Efficacy assessments included lung function (FEV1) in the clinic and asthma symptoms, peak flow rates and bronchodilator use by patients on diary cards. Safety parameters measured included routine haematology and biochemistry (including serum cortisols), clinical adverse events and throat swabs for Candida spp. Both CFC and HFA-formulations of inhaled BDP produced similar and significant improvements in lung function and asthma symptoms. In the low dose study, baseline to endpoint FEV1 increased from 2.2 +/- 0.51 to 2.5 +/- 0.81 (P = 0.0001) with BDP-CFC and from 2.2 +/- 0.51 to 2.6 +/- 0.81 with BDP-HFA (P = 0.0001), with no significant difference between treatments. In the high dose study, corresponding increases were 2.1 +/- 0.71 to 2.4 +/- 0.91 (P = 0.0002) for BDP-CFC and 2.1 +/- 0.71 to 2.3 +/- 0.71 (P = 0.017) for BDP-HFA. PEF also improved similarly on both treatments in both studies. Both formulations were well tolerated with no difference in the pattern of adverse events, effect on serum cortisol or Candida colonization. These studies showed that, in the management of asthma, the new HFA-formulated BDP metered dose inhaler is equivalent to, and directly substitutable for, the older CFC-formulated product at the same dose, making change-over for patients straightforward.

Safety of long-term treatment with HFA albuterol

BACKGROUND

Chlorofluorocarbons (CFCs) used as propellants in metered-dose inhalers deplete stratospheric ozone, which results in serious public health concerns. Albuterol has been reformulated in the non-ozone-depleting propellant, hydrofluoroalkane-134a (HFA albuterol).

OBJECTIVES

The primary objective was to compare the safety of HFA albuterol to an albuterol product formulated in chlorofluorocarbon propellants (CFC albuterol) during 1 year of treatment in asthmatics. Bronchodilator efficacy of the two products was assessed as a secondary objective.

METHODS

The results from two open-label, parallel-group trials of similar design in asthmatics requiring short-acting beta-agonists for symptom control were combined. Patients took two puffs bid of either HFA albuterol or CFC albuterol for 1 year. Additional puffs of study drug were allowed as needed to control asthma symptoms. Adverse events were recorded at clinic visits. Patients self-administered study drug at quarterly visits and underwent serial spirometry during a 6-h period postdose. Bronchodilator efficacy variables, based on FEV1 response to study drug, were proportion of responders, time to onset of effect, peak percent change, time to peak effect, duration of effect, and area under the curve. Differences between products and changes over time in efficacy variables were assessed using an analysis of variance model. Regression analyses with FEV1 as a covariate were performed post-hoc to analyze changes in bronchodilator efficacy over time.

RESULTS

Demographic and baseline characteristics were similar for patients receiving HFA albuterol (n = 337) and CFC albuterol (n = 132). Total reported adverse events were similar for the two treatments. Differences in only four individual adverse events were noted: the HFA albuterol group reported more gastroenteritis and dizziness; the CFC albuterol group reported more epistaxis and expectoration. Adverse events attributed to study drug use were infrequent. No serious adverse events were related to study drug use. Predose FEV1 at quarterly visits increased to a small extent in both groups from month 0 to month 12. The bronchodilator efficacy of HFA albuterol was comparable to that of CFC albuterol at the quarterly visits, but decreased from baseline for both products over the 12 months of treatment. Use of inhaled corticosteroids, nasal corticosteroids, or theophylline did not explain the increase in predose FEV1 over time and did not protect patients from developing reduced bronchodilator efficacy by month 12. The change in predose FEV1 did not entirely account for the reduced bronchodilator efficacy over time.

CONCLUSIONS

HFA albuterol has a safety profile similar to that of CFC albuterol during chronic, scheduled use, and both drugs are well tolerated. HFA albuterol and CFC albuterol provided comparable bronchodilator efficacy, but bronchodilator efficacy decreased for both products with 1 year of use.

Switching patients with asthma from chlorofluorocarbon (CFC) albuterol to hydrofluoroalkane-134a (HFA) albuterol

Chlorofluorocarbon (CFC) propellants deplete stratospheric ozone. Production and use of CFCs, except for certain critical exemptions, has been prohibited by the Montreal Protocol. Use of CFCs as propellants in metered-dose inhalers (MDIs) is still allowed, but the U.S. Food and Drug Administration is planning the transition to alternative propellants for use in MDIs. Hydrofluoroalkane-134a (HFA), a non-ozone-depleting propellant, has been used to reformulate albuterol (HFA albuterol). This study evaluates whether comparable safety and efficacy continues for 12 weeks after patients with asthma are switched from CFC albuterol to HFA albuterol. Patients with asthma stabilized on CFC albuterol during a 12-week safety and efficacy trial were randomized to either continue receiving CFC albuterol or to be switched to receive HFA albuterol in a yearlong safety and efficacy trial. Safety and efficacy were compared over the first 12 weeks of the yearlong trial between patients who had remained on CFC albuterol and those who had been switched to HFA albuterol. Bronchodilator efficacy was evaluated by serial spirometry for 6 hr after the patients self-administered the study drug in the clinic. Safety was assessed by measuring changes in pulse rate, blood pressure, and electrocardiogram (ECG) intervals after dosing with study drug, monitoring adverse events, and performing prestudy and poststudy laboratory testing and physical examinations. No significant differences in bronchodilator efficacy between the patients continuing to receive CFC albuterol and those switched to HFA albuterol were found in the 12 weeks after the switch. No differences between the two products were found for changes in pulse rate, blood pressure, and ECG intervals. Adverse event profiles were similar for the two products, except the patients remaining on CFC albuterol reported increased asthma symptoms and rhinitis significantly more often than the patients switched to HFA albuterol. No clinically meaningful changes in laboratory tests or physical examinations were found in either treatment group. Patients with asthma switched from CFC albuterol to HFA albuterol receive comparable bronchodilation with a similar safety profile as those continuing to receive CFC albuterol.

Cumulative dose response study comparing HFA-134a albuterol sulfate and conventional CFC albuterol in patients with asthma

BACKGROUND

As a result of the pending ban on chlorofluorocarbon production, the non-chlorofluorocarbon propellant 1,1,1,2-tetrafluoroethane (HFA-134a) is being evaluated as a replacement for CFCs in metered-dose inhalers.

OBJECTIVES

This cumulative dose response study compared the safety and bronchodilator efficacy of 16 cumulative inhalations of albuterol sulfate in an HFA-134a, CFC-free propellant system (108 microg of albuterol sulfate, equivalent to 90 microg of albuterol base) with that of equivalent doses of albuterol in a conventional CFC propellant system.

METHODS

Twenty-two patients with at least a 12-month history of stable asthma, who were currently taken an inhaled beta-adrenergic bronchodilator, and who had a FEV1 between 40% and 80% of predicted, were enrolled in this randomized, modified-blind, two-period crossover study. One, 1, 2, 4, and 8 inhalations of study drug were self-administered at 30-minute intervals, resulting in 16 cumulative inhalations. Pulmonary function and safety measures were assessed after each dosing interval.

RESULTS

A significant dose response was found for HFA-134a albuterol sulfate and CFC albuterol with regard to changes in FEV1, serum potassium, heart rate, and blood pressure after 16 cumulative inhalations. No significant differences were demonstrated between HFA-134a albuterol sulfate and CFC albuterol for any FEV1 or safety parameter at any cumulative dose level. No clinically meaningful laboratory or physical examination abnormalities were found with administration of either HFA-134a albuterol sulfate or CFC albuterol.

CONCLUSIONS

HFA-134a albuterol sulfate provides bronchodilation comparable to CFC albuterol and has a similar safety profile.

Postmarketing surveillance study of a non-chlorofluorocarbon inhaler according to the safety assessment of marketed medicines guidelines

OBJECTIVE

To evaluate the safety of a non-chlorofluorocarbon metered dose salbutamol inhaler.

DESIGN

This was a postmarketing surveillance study, conducted under formal guidelines for company sponsored safety assessment of marketed medicines (SAMM). A non-randomised, non-interventional, observational design compared patients prescribed metered doses of salbutamol delivered by inhalers using either hydrofluoroalkane or chlorofluorocarbon as the propellant. Follow up was three months.

SETTING

646 general practices throughout the United Kingdom.

SUBJECTS

6614 patients with obstructive airways disease (1667 patient years of exposure).

MAIN OUTCOME MEASURES

Proportions of patients who were: admitted to hospital for respiratory diseases, reported adverse side effects, or withdrew because of adverse affects.

RESULTS

There were no significant differences between the hydrofluoroalkane (HFA 134a) and chlorofluorocarbon inhaler groups in relation to the proportions of patients admitted to hospital for respiratory diseases (odds ratio 0.75; 95% confidence interval 0.51 to 1.08) or the proportions who reported adverse events (1.01; 0.88 to 1.17). However, more patients using the hydrofluoroalkane inhaler than the chlorofluorocarbon inhaler withdrew because of adverse events (3.8% and 0.9% respectively).

CONCLUSION

The hydrofluoroalkane inhaler was as safe as the chlorofluorocarbon inhaler when judged by hospital admissions and adverse affects. The study design successfully fulfilled the recommendations of the guidelines. Differences between postmarketing surveillance studies and randomised clinical trials in assessing safety were identified. These may lead to difficulties in the design of postmarketing surveillance studies.

Proventil HFA provides bronchodilation comparable to ventolin over 12 weeks of regular use in asthmatics

OBJECTIVE

To compare the bronchodilator effectiveness of albuterol reformulated in the chlorofluorocarbon-free propellant hydrofluoroalkane (HFA)134a (Proventil HFA) to that of Ventolin and HFA placebo over 12 weeks of regular dosing.

DESIGN

Randomized, double-blind, double-dummy, parallel group, placebo-controlled, multi-center trial of asthmatics requiring inhaled beta-adrenergic bronchodilators for symptom control.

INTERVENTIONS

Treatment qid with Proventil HFA, Ventolin, or HFA-134a placebo for 12 weeks.

MEASUREMENTS

At weeks 0, 4, 8, and 12, spirometry was performed predose and serially over 6 h after dosing with study drug. Bronchodilator efficacy variables, based on FEV1 response to study drug, were proportion of responders, time to onset of effect, peak percent change, time to peak effect, duration of effect, and area under the curve (AUC).

RESULTS

Demographic and baseline characteristics were similar for patients randomized to Proventil HFA (193), Ventolin (186), and HFA-134a placebo (186). No significant differences were found between the Proventil HFA and Ventolin treatment groups for any FEV1 efficacy variable, either predose or during 6 h of serial spirometry, at weeks 0, 4, 8, and 12. For all efficacy variables, except time to onset of effect, the Proventil HFA and Ventolin results were significantly greater than placebo. Time to onset of effect for the HFA-134a placebo group is misleading; only 13 patients (7%) were found to be responders in the intent-to-treat database. These efficacy results were found to be consistent across subgroup analyses of inhaled and nasal corticosteroid use, age (18 to 35 and 36 to 66 years), sex, race, weight (<60, 60 to 100, and >100 kg), and baseline FEV1 (< or =55% and >55% predicted). The peak FEV1 effect, duration of FEV1 effect, and AUC for FEV1 were all significantly smaller at weeks 4, 8, and 12 than week 0 for both the Proventil HFA and Ventolin treatment groups.

CONCLUSIONS

Proventil HFA provided bronchodilation comparable to Ventolin and superior effects to HFA-134a placebo over 12 weeks of regular dosing. There was a diminution in bronchodilator response to both Proventil HFA and Ventolin after 4 weeks of use.

Salbutamol delivery from a hydrofluoroalkane pressurized metered-dose inhaler in pediatric ventilator circuits: an in vitro study

STUDY OBJECTIVES

The aim of our study was to determine the in vitro delivery of salbutamol from a pressurized metered-dose inhaler (pMDI) containing hydrofluoroalkane (HFA) propellant through various delivery devices to four models of a pediatric lung.

DESIGN

To determine the effect of electrostatic charge, delivery of salbutamol was initially assessed with a multistage liquid impinger (MSLI) through an inline nonchamber device (Baxter MDI Adapter) and a small (Aerochamber MV) and a large (Nebuhaler) inline chamber device. Following this, the delivery was assessed to four lung models appropriate for a child of 70 kg, 50 kg, 15 kg, and 4 kg, with the same three reduced static devices inserted directly into a pediatric ventilator circuit.

MEASUREMENTS AND RESULTS

Reduction of electrostatic charge improved small particle delivery through holding chambers to the MSLI by 12 to 14%. In the ventilator model, the mean delivery was between 1.9% and 5.4% for the nonchamber device, between 14.3% and 27.2% for the small holding chamber, and between 7.2% and 25.7% for the large holding chamber. Delivery was the least efficient in the 4-kg model compared to the 70-kg, 50-kg, and 15-kg models.

CONCLUSIONS

Salbutamol from an HFA pMDI is delivered efficiently through inline holding chambers with reduced static in pediatric ventilator settings. A large holding chamber has no advantage over a small holding chamber. In addition, salbutamol delivery is more efficient through a holding chamber than through a nonchamber device.

Proventil HFA provides protection from exercise-induced bronchoconstriction comparable to proventil and ventolin

INTRODUCTION

During the 1970s, scientists suggested that the growing use of chlorofluorocarbons (CFCs) was contributing to depletion of the stratospheric ozone layer with potentially harmful results. A committee on the ozone layer organized the preparation of the Montreal Protocol. This protocol mandated the cessation of production and use of CFCs by January 1, 1996. The primary exemption to this ban is for the use of CFCs as propellants in metered dose inhalers (MDIs) for the treatment of asthma. Suitable replacement hydrofluoroalkane (HFA) propellants, such as HFA-134a, for use in MDIs have been identified. Albuterol, a selective beta-adrenergic agonist, currently widely available for inhalation asthma therapy, has been reformulated in HFA-134a (Proventil HFA). OBJECTIVE; To compare the efficacy of Proventil HFA to Ventolin, Proventil, and placebo (HFA-134a) MDI in protecting asthmatic patients from exercise-induced bronchoconstriction.

METHODS

This was a randomized, single-blind, placebo-controlled, 4-period crossover study of asthmatic patients with documented exercise-induced broncho-constriction. Twenty patients self administered two puffs of either Proventil HFA, Ventolin, Proventil or placebo, from an MDI, 30 minutes prior to performing a standardized exercise challenge at the study site. Spirometry was performed predose and 5, 10, 15, 30, 45, 60, 75, and 90 minutes after completion of the exercise challenge. Heart rate and blood pressure were measured just prior to spirometry and a 12-lead ECG was performed 15 minutes after completion of the exercise challenge for measurement of the QT corrected interval.

RESULTS

The primary efficacy variable was the smallest percent change from the predose FEV1 following exercise. The smallest percent change from predose FEV1 for Proventil HFA was 2.0 +/- 9.9 SD, similar to the 2.0 +/- 11.4 SD for Ventolin, and the 3.6 +/- 10.2 SD for Proventil. The smallest percent change from predose FEV1 for each of the active treatments was significantly different from placebo, -23.7 +/- 14.5. Twelve of the patients had a > or = 20% fall in FEV1 post-exercise with placebo pretreatment, but only 1, 1, and 0 had > or = 20% FEV1 falls after treatment with Proventil HFA, Ventolin, and Proventil respectively. Changes in heart rate, blood pressure and QT corrected interval were similar for the three active treatments following exercise.

CONCLUSIONS

Proventil HFA provides protection against exercise-induced bronchoconstriction comparable to Ventolin and Proventil and protection superior to placebo. Proventil HFA has a safety profile similar to Ventolin when used to prevent exercise-induced bronchoconstriction.