Selecting an accessory device with a metered-dose inhaler: variable influence of accessory devices on fine particle dose, throat deposition, and drug delivery with asynchronous actuation from a metered-dose inhaler

Enhancing Inhalation Drug Delivery: A Comparative Study and Design Optimization of a Novel Valved Holding Chamber

This paper presents an innovative approach to the design optimization of valved holding chambers (VHCs), crucial devices for aerosol drug delivery. We present the design of an optimal cylindrical VHC body and introduce a novel valve based on particle impaction theory. The research combines computational simulations and physical experiments to assess the performance of various VHCs, with a special focus on the deposition patterns of medication particles within these devices. The methodology incorporates both experimental and simulation approaches to validate the reliability of the simulation. Emphasis is placed on the deposition patterns observed on the VHC walls and the classification of fine and large particles for salbutamol sulfate particles. The study reveals the superior efficacy of our valve design in separating particles compared to commercially available VHCs. In standard conditions, our valve design allows over 95% of particles under 7 μm to pass through while effectively filtering those larger than 8 μm. The optimized body design accomplishes a 60% particle mass flow fraction at the outlet and an average particle size reduction of 58.5%. When compared numerically in terms of size reduction, the optimal design outperforms the two commercially available VHCs selected. This study provides valuable insights into the optimization of VHC design, offering significant potential for improved aerosol drug delivery. Our findings demonstrate a new path forward for future studies, aiming to further optimize the design and performance of VHCs for enhanced pulmonary drug delivery.

Evaluation of Aerosol Drug Delivery Options during Adult Mechanical Ventilation in the COVID-19 Era

Drug delivery devices used for aerosol therapy during mechanical ventilation to ease the symptoms of respiratory diseases provide beneficial treatment but can also pose challenges. Reflecting the significant changes in global guidance around aerosol usage and lung-protective ventilation strategies, seen in response to the COVID-19 pandemic, for the first time, we describe the drug delivery performance of commonly used devices under these conditions. Here, vibrating mesh nebuliser (VMN), jet nebuliser (JN) and pressurised metered-dose inhaler (pMDI) performance was assessed during simulated adult mechanical ventilation. Both standard test breathing patterns and those representatives of low tidal volume (LTV) ventilation with concurrent active and passive humidification were investigated. Drug delivery using a VMN was significantly greater than that with a JN and pMDI for both standard and LTV ventilation. Humidification type did not affect the delivered dose across all device types for standard ventilation. Significant variability in the pMDI dosing was evident, depending on the timing of actuation and the adapter type used. pMDI actuation synchronised with inspiration resulted in a higher delivered drug dose. The type of adapter used for pMDI actuation influenced drug delivery, with the highest dose observed using the CombiHaler.

Effectiveness of Spacer Devices on Preventing Undesirable Cardiovascular Effects of Inhaled Salbutamol

Background: Currently, there are no regulatory guidelines indicating spacer devices/valved holding chamber (VHC) should be used routinely during pulmonary function tests, and few studies evaluated if spacer devices reduce beta-agonist bronchodilators' side effects. Methods: A prospective study compared salbutamol's cardiovascular effects and bronchodilation response during spirometry tests with and without a spacer device/VHC. Heart rate (HR), the corrected QT interval (QTc), and systolic and diastolic blood pressure were measured 10 minutes after the first spirometry test, before the drug administration, and 20 minutes after inhalation in both groups. Spirometric parameters (forced expiratory volume in the first second [FEV1], forced vital capacity [FVC], and FEV1/FVC) were also measured for both groups. Results: HR and QTc increase were significantly higher in the pressurized meter dose inhalers alone group versus the VHC group [mean SD] [73.1 ± 10 bpm to 74.3 + 10 bpm, p = 0.021] and [median (25%-75% interquartile range)] [389 ms (381-404) to 398 ms (387-407), p = 0.045] vs. [mean SD] [75.4 ± 9 to 73.8 + 8 bpm, p = 0.4] and [median (25%-75% interquartile range)] [388 ms (347-408) to 385 ms (366-408), p = 0.35], respectively. FEV1 variation before and after salbutamol were similar between both groups. Discussion: Although VHC significantly reduces HR and QTc variation when using beta-agonist bronchodilators in healthy patients, no clinical repercussions of this variation were found in this study, since no event of tachycardia or pathological QTc was recorded. Conclusion: VHC has a diminished clinical impact for healthy patients when considering cardiovascular effects and spirometric parameters. Beta-agonist bronchodilators may be administrated despite the use of spacer devices in patients without known cardiovascular diseases. Its significance for other populations still needs to be determined.

Medical devices in allergy practice

Medical devices provide people with some health benefits in terms of diagnosis, prevention, treatment, and monitoring of disease processes. Different medical specialties use varieties of medical devices more or less specific for them. Allergology is an interdisciplinary field of medical science and teaches that allergic reactions are of systemic nature but can express themselves at the level of different organs across the life cycle of an individual. Subsequently, medical devices used in allergology could be regarded as: 1) general, servicing the integral diagnostic and management principles and features of allergology, and 2) organ specific, which are shared by organ specific disciplines like pulmonology, otorhinolaryngology, dermatology, and others. The present position paper of the World Allergy Organization (WAO) is meant to be the first integral document providing structured information on medical devices in allergology used in daily routine but also needed for sophisticated diagnostic purposes and modern disease management. It is supposed to contribute to the transformation of the health care system into integrated care pathways for interrelated comorbidities.

Evaluation of a structured pharmacist-led inhalation technique assessment service for patients with asthma and COPD in Norwegian pharmacies

OBJECTIVE

To investigate whether the inhalation technique improved among patients with asthma and chronic obstructive pulmonary disease after an Inhalation Technique Assessment Service (ITAS), and to assess the patients' and pharmacists' perceptions of ITAS.

METHODS

This uncontrolled, pre-post study included 405 patients recruited from 42 Norwegian pharmacies. Inhalation technique was assessed by trained pharmacists before ITAS (baseline), directly after (follow-up 1) and three months after ITAS (follow-up 2), and analyzed statistically using SPSS. Perceptions of ITAS were assessed using a questionnaire.

RESULTS

488 ITAS were performed. At baseline, 8% of the inhalation technique demonstrations were rated as optimal and 31% as acceptable. Following ITAS, this increased to 72% (optimal) and 86% (acceptable). At follow-up 2 inhalation technique remained significantly higher than baseline (optimal: 52%, acceptable: 75%). The median rate of wrong steps decreased from 25% (baseline) to 0% (follow-ups). The usefulness of ITAS was rated 4 on a 5-point Likert scale.

CONCLUSION

Inhalation technique improved significantly after ITAS for both new and experienced users and all assessed devices. The technique remained significantly improved at follow-up 2. ITAS was well accepted by pharmacists and patients.

PRACTICE IMPLICATIONS

ITAS can contribute to significant improvements in inhalation technique among patients using inhaler devices.

Usefulness of Nonvalved Spacers for Administration of Inhaled Steroids in Young Children with Recurrent Wheezing and Risk Factors for Asthma

Background

In vitro and scintigraphic studies have suggested that effectiveness of metered-dose inhalers (MDI) with nonvalved spacers (NVS) is similar to that of MDI with valved holding chambers (VHC). Nevertheless, there are no clinical studies that compare these techniques in long-term treatment with inhaled steroids in young children with recurrent wheezing and risk factors for asthma.

Objective

To compare the efficacy of a long-term treatment with Fluticasone Propionate administered by an MDI through both type of spacers, with and without valves, in young children with recurrent wheezing and risk factors for asthma.

Patients and Methods

Outpatient children (6 to 20 months old) with recurrent wheezing and risk factors for asthma were randomized to receive a 6-month treatment with metered-dose inhaler (MDI) of Fluticasone Propionate 125 mcg BID through an NVS or through a VHC. Parents recorded daily their child's respiratory symptoms and rescue medication use.

Results

46 patients of 13.4 ± 5 months old were studied. During the study period, the NVS group (n=25) experienced 3.9 ± 2.4 obstructive exacerbations, and the VHC group (n=21) had 2.6 ± 1.6 (p=0.031). The NVS group had 17.4 ± 14% of days with respiratory symptoms, and the VHC group had 9.7 ± 7% (p=0.019). The NVS group spent 29.8 ± 22 days on albuterol while the VHC group spent 17.9 ± 11 days (p=0.022).

Conclusion

Long-term treatment with inhaled steroids administered by MDI and NVS is less effective than such treatment by MDI and VHC in infants with recurrent wheezing and risk factors for asthma.

Spacer devices for inhaled therapy: why use them, and how?

We present an extensive review of the literature to date pertaining to the rationale for using a spacer/valved holding chamber (VHC) to deliver inhaled therapy from a pressurised, metered-dose inhaler, a discussion of how the properties of individual devices may vary according to their physical characteristics and materials of manufacture, the potential risks and benefits of ancillaries such as valves, and the evidence that they contribute tangibly to the delivery of therapy. We also reiterate practical recommendations for the correct usage and maintenance of spacers/VHCs, which we trust offer practical help and advice to patients and healthcare professionals alike.

A review of the in vitro and in vivo valved holding chamber (VHC) literature with a focus on the AeroChamber Plus Flow-Vu Anti-static VHC

Valved holding chambers (VHCs) reduce the need for inhalation-actuation coordination with pressurized metered dose inhalers (pMDIs), reduce oropharyngeal drug deposition and may improve lung deposition and clinical outcomes compared to pMDIs used alone. While VHCs are thus widely advocated for use in vulnerable patient groups within clinical and regulatory guidelines, there is less consensus as to whether the performance differences between different VHCs have clinical implications. This review evaluates the VHC literature, in particular the data pertaining to large- versus small-volume chambers, aerosol performance with a VHC adjunct versus a pMDI alone, charge dissipative/conducting versus non-conducting VHCs, and facemasks, to ascertain whether potentially meaningful differences between VHCs exist. Inconsistencies in the literature are examined and explained, and relationships between in vitro and in vivo data are discussed. A particular focus of this review is the AeroChamber Plus® Flow-Vu® Anti-static VHC, the most recent iteration of the AeroChamber VHC family.

Inhalation devices: from basic science to practical use, innovative vs generic products

INTRODUCTION

Inhalation therapy is a convenient method of treating respiratory diseases. The key factors required for inhalation are the preparation of drug carriers (aerosol particles) allowing reproducible dosing during administration. These technical challenges are accomplished with a variety of inhalation devices (inhalers) and medicinal formulations, which are optimized to be easily converted into inhalable aerosols. Areas covered: This review is focused on the most important, but often overlooked, effects, which are required for the reliable and reproducible inhalable drug administration. The effects of patient-related issues that influence inhalation therapy, such as proper selection of inhalers for specific cases is discussed. We also discuss factors that are the most essential if generic inhalation product should be considered equivalent to the drugs with the clinically confirmed efficacy. Expert opinion: Proper device selection is crucial in clinical results of inhalation therapy. The patients' ability to coordinate inhalation with actuation, generation of optimal flow through the device, use of optimal inspiratory volume, all produces crucial effects on disease control. Also the severity of the disease process effects proper use of inhalers. Interchanging of inhalers can produce potentially conflicting problem regarding efficacy and safety of inhalation therapy.

In vitro evaluation of nonconventional accessory devices for pressurized metered-dose inhalers

BACKGROUND

The selection of accessory devices for pressurized metered-dose inhalers (pMDIs) by health care professionals is typically cost driven without consideration of how the device modifies clinical outcomes.

OBJECTIVE

To evaluate nonconventional accessory devices and the open-mouth technique with and without ideal coordination of actuation and inhalation to identify and understand the considerations for recommending potential inexpensive devices.

METHODS

In vitro performance parameters of the beclomethasone dipropionate pMDI were evaluated with several devices (AeroChamber, toilet paper roll, paper towel roll, rolled paper, plastic bottle spacer, bottle-holding chamber, and nebulizer reservoir tubing).

RESULTS

Compared with the pMDI alone, all the accessory devices evaluated have significantly lower drug exposure and throat deposition and higher respirable fractions, with the paper towel roll having the greatest effect of the devices evaluated (exposure decreased from a mean [SD] of 76.1 [4.8] μg to 49.2 [2.0] μg, throat deposition decreased from 32.0 [3.2] μg to 0.8 [0.3] μg, and respirable fraction increased from 49.8% [3.2%] to 96.4% [0.4%]). Introduction of a delay between actuation and inhalation resulted in greater variability in performance metrics for the devices evaluated, and the bottle-holding chamber and paper towel roll were most effective in mitigating the effect of the delay. The open-mouth technique was found to decrease throat deposition and respirable mass compared with the pMDI alone.

CONCLUSION

In addition to cost, the amount of drug that deposits in the throat and the lungs and the effect of asynchronous actuation and inhalation can vary with the selection of an accessory device, which may affect the therapeutic benefits of the pMDI selected.

Inhaler devices for patients with COPD

Chronic obstructive pulmonary disease (COPD) continues to be associated with increased morbidity and mortality risk in spite of updated guidelines and a better understanding of this condition. Progressive airflow limitation and resultant hyperinflation-the respiratory hallmarks of this complex and often under-diagnosed disease-can be treated with pharmacotherapies emitted via nebulizers, pressurized metered-dose inhalers, dry powder inhalers, or a Soft Mist inhaler. Pharmaceutical company proprietary issues, technological innovations, and societal pressure have expanded the list of available inhalers, with a limited range of medications available for any one device. Each device has different operating and maintenance instructions, and successful use of a given drug/device combination requires that patients understand, maintain, and use each of their devices properly in order to ensure consistent and optimal pulmonary drug delivery. Clinicians are faced with a range of physical and psychosocial issues unique to each patient with COPD that must be overcome in order to match a suitable inhaler to the individual. Improved drug delivery afforded by next-generation inhalers, coupled with an awareness of device-specific and patient-specific variables affecting inhaler use, may improve clinical outcomes in the treatment of COPD.

Comparison of the bronchodilating effects of albuterol delivered by valved vs. non-valved spacers in pediatric asthma

INTRODUCTION

Inhaled therapy using a metered-dose inhaler (MDI) with attached valved holding chamber has been increasingly recognized as the optimal method for delivering bronchodilators for asthma treatment. However, mainly due to the high cost of these valved holding chambers in many developing countries, the use of non-valved spacers is frequent, despite the scarce evidence that supports their efficacy. The aim of this study was to compare the bronchodilator response to albuterol administered by MDI with and without a valved spacer.

METHODS

In a randomized, two-period, two-sequence crossover clinical trial, we analyzed 31 stable asthmatic children (6-18 yrs of age) on two consecutive days, who were randomly assigned to receive 100 μg of albuterol MDI through either a locally produced valved spacer or a non-valved spacer. The next day, a crossover treatment was employed through the use of the other spacer. Spirometry was recorded before and after each albuterol administration.

RESULTS

As we were not able to identify any sequence or carryover effect, we tested for treatment effects in both periods. No significant differences in the absolute change in FEV(1) (0.20 ± 0.17 vs. 0.18 ± 0.16, p = 0.63), FVC (0.07 ± 0.13 vs. 0.07 ± 0.16, p = 0.88), or MMEF (0.49 ± 0.31 vs. 0.43 ± 0.39, p = 0.53) after bronchodilator administration were found between the use of valved and non-valved spacers.

CONCLUSIONS

In stable asthmatic children, albuterol administered through MDI using a non-valved spacer produces a bronchodilator response similar to that of a spacer with a valve that requires an inhalatory opening pressure (with flows between 2 and 32 l/min) that even toddlers with bronchial obstruction can easily generate.

Guidelines for aerosol devices in infants, children and adults: which to choose, why and how to achieve effective aerosol therapy

Multiple types of aerosol devices are commonly used for the administration of medical aerosol therapy to patients with pulmonary diseases. All of these devices have been shown to be effective in trials where they are used correctly. However, failure to operate any of these devices properly has been associated with poor clinical response and limited patient adherence to therapy. Therefore, the selection of the best aerosol device for the individual patient is very important for optimizing the results of medical aerosol therapy. This article presents the rationale for selecting the most appropriate aerosol device to administer inhaled drugs in specific patient populations, with emphasis on patient-, drug-, device- and environment-related factors and with a comparison between the available devices. The following recommendations for the selection of the 'best' aerosol device for each patient population are intended to help clinicians gain a clear understanding of the specific issues and challenges so that they can optimize aerosol drug delivery and its therapeutic outcomes in patients.

Teaching inhaler use in chronic obstructive pulmonary disease patients

PURPOSE

To review barriers to the successful use of inhalers in patients with chronic obstructive pulmonary disease (COPD), and the role of the nurse practitioner (NP) in facilitating optimum inhaler use.

DATA SOURCES

Review of the national and international scientific literature.

CONCLUSIONS

Pharmacologic treatment of COPD patients comprises mainly inhaled medications. Incorrect use of inhalers is very common in these individuals. Some of the consequences of poor inhaler technique include reduced therapeutic dosing, medication adherence, and disease stability, which can lead to increased morbidity, decreased quality of life, and a high burden on the healthcare system. Knowledgeable evaluation and frequent reassessment of inhaler use coupled with education of patients, caregivers, and healthcare professionals can significantly improve the benefits COPD patients derive from inhaled therapy.

IMPLICATIONS FOR PRACTICE

Patient education is vital for correct use of inhalers and to ensure the effectiveness of inhaled medications. The NP has a critical role in assessing potential barriers to successful learning by the patient and improving inhaler technique and medication management. The NP can also facilitate success with inhaled medications by providing up-to-date inhaler education for other healthcare team members, who may then act as patient educators.

Ultrasonic nebulization platforms for pulmonary drug delivery

IMPORTANCE OF THE FIELD

Since the 1950s, ultrasonic nebulizers have played an important role in pulmonary drug delivery. As the process in which aerosol droplets are generated is independent and does not require breath-actuation, ultrasonic nebulizers, in principle, offer the potential for instantaneously fine-tuning the dose administered to the specific requirements of a patient, taking into account the patient's breathing pattern, physiological profile and disease state. Nevertheless, owing to the difficulties and limitations associated with conventional designs and technologies, ultrasonic nebulizers have never been widely adopted, and have in recent years been in a state of decline.

AREAS COVERED IN THIS REVIEW

An overview is provided on the advances in new miniature ultrasonic nebulization platforms in which large increases in lung dose efficiency have been reported.

WHAT THE READER WILL GAIN

In addition to a discussion of the underlying mechanisms governing ultrasonic nebulization, in which there appears to be widely differing views, the advantages and shortcomings of conventional ultrasonic nebulization technology are reviewed and advanced state-of-the-art technologies that have been developed recently are discussed.

TAKE HOME MESSAGE

Recent advances in ultrasonic nebulization technology demonstrate significant potential for the development of smart, portable inhalation therapy platforms for the future. Nevertheless, there remain considerable challenges that need to be addressed before such personalized delivery systems can be realized. These have to be addressed across the spectrum from fundamental physics through to in vivo device testing and dealing with the relevant regulatory framework.

Population pharmacodynamic model of bronchodilator response to inhaled albuterol in children and adults with asthma

BACKGROUND

Because interpatient variability in bronchodilation from inhaled albuterol is large and clinically important, we characterized the albuterol dose/response relationship by pharmacodynamic modeling and quantified variability.

METHODS

Eighty-one patients with asthma (24% African American [AA]; 8 to 65 years old; baseline FEV1, 40 to 80% of predicted) received 180 microg of albuterol from a metered-dose inhaler (MDI), and then 90 microg every 15 min until maximum improvement or 540 microg was administered; all then received 2.5 mg of nebulized albuterol. FEV1 was measured 15 min after each dose. The population cumulative dose/response data were fitted with a sigmoid maximum effect of albuterol (Emax) [maximum percentage of predicted FEV1 effect] model by nonlinear mixed-effects modeling. The influence of covariates on maximum percentage of predicted FEV1 reached after albuterol administration (Rmax) and cumulative dose of albuterol required to bring about 50% of maximum effect of albuterol (ED50) and differences between AA and white patients were explored.

RESULTS

ED50 was 141 microg, and Emax was 24.0%. Coefficients of variation for ED50 and Emax were 40% and 56%, respectively. Ethnicity was a statistically significant covariate (p < 0.05). AA and white patients reached 82.4% and 91.9% of predicted FEV1, respectively (p = 0.0004); and absolute improvement in percentage of predicted FEV1 was 16.6% in AA patients vs 26.7% in white patients (p < 0.0003). There were no baseline characteristic differences between AA and white patients. Nebulized albuterol increased FEV1 > or = 200 mL in 21% of participants. Heart rate and BP were unchanged from baseline after maximal albuterol doses.

CONCLUSIONS

Our model predicts that 180 microg of albuterol by MDI produces a 14.4% increase in percentage of predicted FEV1 over baseline (11.7% in AA patients, and 17.5% in white patients). Emax varies widely between asthmatic patients. AA patients are less responsive to maximal doses of inhaled albuterol than white patients.

Use of Respimat Soft Mist inhaler in COPD patients

Events of the past decade have stimulated development of new drug formulations and delivery devices that have improved the efficiency, ease of use, and environmental impact of inhaled drug therapy. Respimat^® Soft Mist™ Inhaler is a novel, multidose, propellant-free, hand-held, liquid inhaler that represents a new category of inhaler devices. The aerosol cloud generated by Respimat contains a higher fraction of fine particles than most pressurized metered dose inhalers (pMDIs) and dry powder inhalers (DPIs), and the aerosol spray exits the inhaler more slowly and for a longer duration than with pMDIs. This translates into higher lung drug deposition and lower oropharyngeal deposition, making it possible to give lower nominal doses of delivered drugs without lowering efficacy. In clinical trials in patients with COPD, bronchodilator drugs delivered from Respimat were equally effective at half of the dose delivered from a pMDI. In one study of inhaler preference, Respimat was preferred over the pMDI by patients with COPD and other obstructive lung diseases. Respimat is a valuable addition to the range of inhaler devices available to the patient with COPD.

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.

In vitro performance of two common valved holding chambers with a chlorofluorocarbon-free beclomethasone metered-dose inhaler

STUDY OBJECTIVE

To compare in vitro aerosol deposition from a beclomethasone dipropionate metered-dose inhaler (MDI) containing hydrofluoroalkane propellant with that of the MDI in combination with two common valved holding chambers (VHCs) to evaluate how these VHCs affect the respirable dose of beclomethasone dipropionate.

DESIGN

In vitro aerosol deposition study.

SETTING

University research center.

DEVICES

Beclomethasone dipropionate hydrofluoroalkane MDI alone, the MDI with OptiChamber VHC, and the MDI with AeroChamber-Plus VHC.

INTERVENTION

The respirable dose (1-5-microm aerosol particles) of beclomethasone dipropionate was determined by sampling 10 80-microg actuations from five runs with each configuration (MDI alone, MDI with OptiChamber, and MDI with AeroChamber-Plus), using a well-established in vitro cascade impactor method.

MEASUREMENTS AND MAIN RESULTS

Beclomethasone dipropionate aerosol was washed from the impactor with 50% methanol and quantified by means of high-performance liquid chromatography. Differences among outcomes were determined by using analysis of variance. Mean beclomethasone dipropionate respirable dose from AeroChamber-Plus (27.2 +/- 10.0 microg/actuation) was not significantly different (p>0.05) from that of the MDI alone (29.0 +/- 7.0 microg/actuation). OptiChamber respirable dose (12.8 +/- 6.0 microg/actuation) was less than half that produced by either the AeroChamber-Plus or the MDI alone (p=0.013).

CONCLUSIONS

The OptiChamber and AeroChamber-Plus VHCs do not demonstrate equivalent in vitro performance when used with a beclomethasone dipropionate MDI that contains hydrofluoroalkane propellant. The respirable dose of beclomethasone dipropionate aerosol from the hydrofluoroalkane MDI was decreased by only 6% when the MDI was mated to an AeroChamber-Plus VHC and by 56% when used with an OptiChamber VHC.

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

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

In Vitro Performance Characteristics of Valved Holding Chamber and Spacer Devices with a Fluticasone Metered-Dose Inhaler

STUDY OBJECTIVE

To compare the in vitro aerosol deposition characteristics of several commercially available valved holding chamber (VHC) and spacer devices used with a fluticasone metered-dose inhaler (MDI).

DESIGN

In vitro aerosol deposition study

SETTING

University-affiliated research center.

DEVICES

Seven VHC devices: BreatheRite, E-Z Spacer, EasiVent, AeroChamber, InspirEase, OptiChamber, and Space Chamber. Six spacer devices: OptiHaler, Aerosol Cloud Enhancer (ACE), Gentle-Haler, MediSpacer, Ellipse, and a 6-inch tube (1-inch inside diameter).

INTERVENTION

The respirable dose (aerosol particles 1-5 microm) of fluticasone was determined by sampling 10 220-microg actuations from five runs with each spacer or VHC plus MDI combination, by using a well-established in vitro cascade impactor method.

MEASUREMENTS AND MAIN RESULTS

Fluticasone aerosol was washed from the impactor with methanol and quantified by means of high-performance liquid chromatography. Differences among outcomes were determined with analysis-of-variance testing. Among spacers, Ellipse had the highest respirable dose (104 microg, p < 0.01). Respirable doses for the 6-inch tube (74.3 microg), Gentle-Haler (81.7 microg), and MediSpacer (82.6 microg) were no different from that of the MDI (p > 0.05), whereas respirable doses of OptiHaler (44.6 microg) and ACE (47.2 microg) were less than those of all other spacers (p < 0.001). Among VHC devices, respirable doses from EasiVent (35.6 microg), AeroChamber (47.0 microg), InspirEase (52.7 microg), OptiChamber (53.1 microg), and Space Chamber (58.3 microg) were not different (p > 0.05), whereas BreatheRite (13.1 microg) and E-Z Spacer (27.3 microg) respirable doses were less than those of the other VHC devices (p < 0.05).

CONCLUSION

Spacers and VHC devices available in the United States do not demonstrate equivalent in vitro performance with the fluticasone MDI. The difference between highest and lowest respirable doses in each device category would likely lead to clinically relevant differences in the quantity of fluticasone delivered to a patient.

The delivery of inhaled medication to the young child

The effective and efficient delivery of aerosol medications involves physician factors (correct diagnosis and correct prescription of appropriate medications), device factors, and patient factors. For nearly all infants and children, the authors administer asthma medications either using a pMDI with a valved holding chamber or a DPI. Regardless of the device chosen, parent and patient education is critical for the appropriate use of the device, and frequent reinforcement of the educational message will often improve adherence and correct use.