Inhaler devices in infants and children: challenges and solutions

Survey-based investigation into the current use of paediatric medicines and administration devices in China

The accurate, rapid and convenient administration of medicines to children is not possible without the use of appropriate administration devices. However, due to the unique nature of this patient population, inappropriate paediatric medication administration has been widely observed worldwide. According to previous surveys carried out in other countries including the UK and Japan, there has been a wide variation in the handling of paediatric devices among children. To date, little is known about the current situation in China where the variety of available paediatric administration devices is more limited than in Europe and the UK. The aim of this study was therefore to conduct a China-wide survey to gain a better understanding of the perspectives of children and their caregivers on paediatric medicines and devices. This study was conducted throughout China with 215 children as well as 749 caregivers of paediatric year groups from 1 to less than 18 years old. The majority of participants (83%) took oral dosage forms where granules, syrup and tablets were ranked as the Top 3 commonly used oral dosage forms. The most commonly used devices, i.e., measuring cups (47.3%) and household spoons (41.1%) were both well accepted by the vast majority of children. More instruction and demonstration by the healthcare professionals were provided to inhalation devices users with the nebuliser and facemask being the most commonly used. In particular, the role of pharmacists in China is expected to be better defined, which may in turn help with the education provided to paediatric users in operating medical devices. The data collected varied considerably with the age of children but not statistically significantly with the region in which the survey was conducted.

Near Elimination of In Vitro Predicted Extrathoracic Aerosol Deposition in Children Using a Spray-Dried Antibiotic Formulation and Pediatric Air-Jet DPI

PURPOSE

This study evaluated the in vitro aerosol performance of a dry powder antibiotic product that combined a highly dispersible tobramycin powder with a previously optimized pediatric air-jet dry powder inhaler (DPI) across a subject age range of 2-10 years.

METHODS

An excipient enhanced growth (EEG) formulation of the antibiotic tobramycin (Tobi) was prepared using a small particle spray drying technique that included mannitol as the hygroscopic excipient and trileucine as the dispersion enhancer. The Tobi-EEG formulation was aerosolized using a positive-pressure pediatric air-jet DPI that included a 3D rod array. Realistic in vitro experiments were conducted in representative airway models consistent with children in the age ranges of 2-3, 5-6 and 9-10 years using oral or nose-to-lung administration, non-humidified or humidified airway conditions, and constant or age-specific air volumes.

RESULTS

Across all conditions tested, mouth-throat depositional loss was < 1% and nose-throat depositional loss was < 3% of loaded dose. Lung delivery efficiency was in the range of 77.3-85.1% of loaded dose with minor variations based on subject age (~ 8% absolute difference), oral or nasal administration (< 2%), and delivered air volume (< 2%). Humidified airway conditions had an insignificant impact on extrathoracic depositional loss and significantly increased aerosol size at the exit of a representative lung chamber.

CONCLUSIONS

In conclusion, the inhaled antibiotic product nearly eliminated extrathoracic depositional loss, demonstrated high efficiency nose-to-lung antibiotic aerosol delivery in pediatric airway models for the first time, and provided ~ 80% lung delivery efficiency with little variability across subject age and administered air volume.

Inhalation Devices in 7- to 15-Year-Old Children with Asthma - A Patient Preference Study

Background

Inhalation therapy is the cornerstone of treatment of bronchial asthma. A patient-specific selection of inhalation devices is necessary, as preference for a device plays an important role in terms of error rates in handling and adherence to therapy. However, there is no industry-independent study providing information on children's preferences for common inhaler types. The aim of the present study was to investigate the preference of asthmatic children for inhaler types commonly used in Germany. The effects of age, gender and the type of school visited on device preferences as well as the frequency of patient education and the role of health care providers in the choice for an inhaler were investigated.

Methods

Eighty children were included in this prospective cross-sectional study (age: 10.87 ± 2.62 years). The analysis was based on a questionnaire and validated checklists. All participants tested the use of nine placebo inhalers (Breezhaler, Diskus, Respimat, Spiromax, Turbohaler, Autohaler, metered-dose inhaler, Easyhaler and Novolizer) in a randomized order. For each device, patients were asked to assess handling, rate different device characteristics and name the device they would prefer most or least.

Results

The most favored device was the Novolizer. Moreover, the Spiromax scored highest in numerous categories such as suitability in emergencies and "easiest" device to use. Patient preferences with respect to the addressed inhaler features were not significantly related to age, gender or school type.

Conclusion

The Novolizer and the Spiromax showed higher preference in pediatric patients as compared to other tested devices. Overall, there were significant differences in terms of preference when comparing the tested inhalers in different aspects.

Development of a High-Dose Infant Air-Jet Dry Powder Inhaler (DPI) with Passive Cyclic Loading of the Formulation

PURPOSE

The objective of this study was to incorporate a passive cyclic loading strategy into the infant air-jet dry powder inhaler (DPI) in a manner that provides high efficiency aerosol lung delivery and is insensitive to powder mass loadings and the presence of downstream pulmonary mechanics.

METHODS

Four unique air-jet DPIs were initially compared and the best performing passive design (PD) was selected for sensitivity analyses. A single preterm in vitro nose-throat (NT) model, air source, and nasal interface were utilized throughout. While the majority of analyses were evaluated with a model spray-dried excipient enhanced growth (EEG) formulation, performance of a Surfactant-EEG formulation was also explored for the lead DPI design.

RESULTS

Two devices, PD-2 and PD-3, evaluated in the preterm model achieved an estimated lung delivery efficiency of 60% with the model EEG formulation, and were not sensitive to the loaded dose (10-30 mg of powder). The PD-3 device was also unaffected by the presence of downstream pulmonary mechanics (infant lung model) and had only a minor sensitivity to tripling the volume of the powder reservoir. When using the Surfactant-EEG formulation, increasing the actuation flow rate from 1.7 to 4.0 L/min improved lung delivery by nearly 10%.

CONCLUSIONS

The infant air-jet DPI platform was successfully modified with a passive cyclic loading strategy and capable of providing an estimated > 60% lung delivery efficiency of a model spray-dried formulation with negligible sensitivity to powder mass loading in the range of 10-30 mg and could be scaled to deliver much higher doses.

Mask Use with Spacers/Valved Holding Chambers and Metered Dose Inhalers among Children with Asthma

Inhaler misuse is highly prevalent and associated with high morbidity and costs. For metered dose inhalers, proper use can be supported with devices such as spacers/valved holding chambers (VHCs) and masks to effectively deliver inhaled medication to the lungs. However, guidelines are vague about which children with asthma should use spacers/VHCs with masks to deliver medication from metered dose inhalers as well as when they should transition to spacers/VHCs with mouthpieces. In this paper, we provide a focused review of the evidence for mask use, highlighting unclear and conflicting information in guidelines and studies. We synthesize the differences in recommendations and practice. Based on these findings, we call for future research to determine the appropriate age and necessary skills for transitioning children from using metered dose inhalers with spacers/VHCs and masks to using spacers/VHCs and mouthpieces. Guidelines about mask use should be standardized to help ensure optimal medical delivery for patients, provide consistent inhaler prescriptions and education across settings, and support team-based care to help lower pediatric asthma morbidity and costs.

A path to successful patient outcomes through aerosol drug delivery to children: a narrative review

Although using aerosolized medications is a mainstay of treatment in children with asthma and other respiratory diseases, there are many issues in terms of device and interface selection, delivery technique and dosing, as well as patient and parental education that have not changed for half a century. Also, due to many aerosol devices and interfaces available on the market and the broad range of patient characteristics and requirements, providing effective aerosol therapy to children becomes a challenge. While aerosol delivery devices are equally effective, if they are age-appropriate and used correctly, the majority of aerosol devices require multiple steps to be used efficiently. Unfortunately, many children with pulmonary diseases have problems with the correct delivery technique and do not gain therapeutic benefits from therapy that result in poor disease management and increased healthcare costs. Therefore, the purpose of this paper is to review the current knowledge on aerosol delivery devices used in children and guide clinicians on the optimum device- and interface-selection, delivery technique, and dosing in this patient population. Strategies on how to deliver aerosolized medications in crying and distressed children and how to educate parents on aerosol therapy and promote patient adherence to prescribed medications are also provided. Future directions of aerosol therapy in children should focus on these issues and implement policies and clinical practices that highlight the potential solutions to these problems.

High-Efficiency Dry Powder Aerosol Delivery to Children: Review and Application of New Technologies

While dry powder aerosol formulations offer a number of advantages, their use in children is often limited due to poor lung delivery efficiency and difficulties with consistent dry powder inhaler (DPI) usage. Both of these challenges can be attributed to the typical use of adult devices in pediatric subjects and a lack of pediatric-specific DPI development. In contrast, a number of technologies have recently been developed or progressed that can substantially improve the efficiency and reproducibility of DPI use in children including: (i) nose-to-lung administration with small particles, (ii) active positive-pressure devices, (iii) structures to reduce turbulence and jet momentum, and (iv) highly dispersible excipient enhanced growth particle formulations. In this study, these technologies and their recent development are first reviewed in depth. A case study is then considered in which these technologies are simultaneously applied in order to enable the nose-to-lung administration of dry powder aerosol to children with cystic fibrosis (CF). Using a combination of computational fluid dynamics (CFD) analysis and realistic in vitro experiments, device performance, aerosol size increases and lung delivery efficiency are considered for pediatric-CF subjects in the age ranges of 2-3, 5-6 and 9-10 years old. Results indicate that a new 3D rod array structure significantly improves performance of a nasal cannula reducing interface loss by a factor of 1.5-fold and produces a device emitted mass median aerodynamic diameter (MMAD) of 1.67 μm. For all ages considered, approximately 70% of the loaded dose reaches the lower lung beyond the lobar bronchi. Moreover, significant and rapid size increase of the aerosol is observed beyond the larynx and illustrates the potential for targeting lower airway deposition. In conclusion, concurrent CFD and realistic in vitro analysis indicates that a combination of multiple new technologies can be implemented to overcome obstacles that currently limit the use of DPIs in children as young as two years of age.

Initial Development of an Air-Jet Dry Powder Inhaler for Rapid Delivery of Pharmaceutical Aerosols to Infants

Background: Positive-pressure dry powder inhalers (DPIs) have recently been developed that in combination with highly dispersible spray-dried powder formulations can achieve high efficiency aerosolization with low actuation air-volumes (AAVs). The objective of this study was to initially develop the positive-pressure air-jet DPI platform for high efficiency aerosol delivery to newborn infants by using the nose-to-lung route. Methods: Aerosolization performance metrics of six air-jet DPIs were first assessed at AAVs that were consistent with full-term (30 mL) and preterm (10 mL) neonates. Designs of the air-jet DPIs varied based on geometry of the inlet and outlet flow passages and shape of the aerosolization chamber. Aerosolization metrics evaluated at the device outlet were emitted dose (ED) and mass median aerodynamic diameter (MMAD). Designs with the best aerosolization performance were connected to a smoothly expanding nasal interface and full-term infant (3550 g) nose-throat (NT) model with tracheal filter. Results: The three best performing devices had characteristics of a cylindrical and horizontal aerosolization chamber with a flush or protruding outlet orifice. Including multiple air inlets resulted in meeting the aerosolization targets of >80% ED (based on loaded dose) and MMAD <1.8 μm. Reducing the AAV by a factor of threefold from 30 to 10 mL had little effect on aerosol formation. The three leading devices all delivered ∼50% of the loaded dose through a full-term NT in vitro model by using an AAV of 30 mL. Conclusion: With careful selection of design attributes, the air-jet DPI platform is capable of high-efficiency aerosolization of a 10 mg powder mass by using AAVs that are consistent with infant inhalation. The associated infant air-jet DPI system, which forms a seal at the nostril(s) and delivers both the aerosol and a complete inhalation, is capable of rapid and efficient aerosol administration to infant lungs, based on initial testing in a full-term in vitro NT model.

In vitro evaluation of aerosol drug delivery with and without high flow nasal cannula in children

OBJECTIVE

To quantify aerosol delivery with or without a high flow nasal cannula (HFNC) in place using pressurized metered-dose inhaler (pMDI) and jet nebulizer (JN) with facemask in a simulated spontaneously breathing pediatric lung model.

METHODS

An upper airway model of a 9-month-old infant (Sophia Anatomical Infant Nose-Throat) with an absolute filter distal to the trachea was connected to a breathing simulator to simulate pediatric parameters (tidal volume = 100 mL, respiratory rate = 30 breaths/min, and I:E ratio = 1:1.4). Oxygen at 3 L/min was administered through an infant HFNC (Fisher & Paykel Healthcare Ltd, Auckland, New Zealand) attached to the nares of the model. Albuterol sulfate (2.5 mg/3 mL) was delivered with JN attached to an aerosol facemask and powered by air at 8 L/min. Ventolin Hydrofluoroalkane (HFA) (360 μg) was administered using pMDI connected to a valved holding chamber (VHC) with a facemask. Aerosol was administered to the model with and without HFNC in the nares (n = 3). Drug was eluted from the filter and quantified using spectrophotometry. Independent t tests were performed for data analysis (P < .05).

RESULTS

Aerosol deposition was greater without HFNC (6.05% ± 1.53% and 39.54% ± 8.98% for JN and pMDI/VHC, respectively) than with HFNC using JN (2.91% ± 0.23%; P = .024) and pMDI/VHC (6.04% ± 0.28%; P = .003). Delivery efficiency of pMDI/VHC was greater than JN with or without nasal cannula in place (P = .0001 and .003, respectively).

CONCLUSION

Aerosol administered via facemask over HFNC was less efficient than removing HFNC during administration. When delivering medical aerosol by facemask, the benefit of increased aerosol delivery must be weighed against the changes in oxygen delivery and risk of lung derecruitment when nasal prongs are removed.

Development of an Inline Dry Powder Inhaler for Oral or Trans-Nasal Aerosol Administration to Children

Background: Dry powder inhalers (DPIs) offer a number of advantages, such as rapid delivery of high-dose inhaled medications; however, DPI use in children is often avoided due to low lung delivery efficiency and difficulty in operating the device. The objective of this study was to develop a high-efficiency inline DPI for administering aerosol therapy to children with the option of using either an oral or trans-nasal approach. Methods: An inline DPI was developed that consisted of hollow inlet and outlet capillaries, a powder chamber, and a nasal or oral interface. A ventilation bag or compressed air was used to actuate the device and simultaneously provide a full deep inspiration consistent with a 5-year-old child. The powder chamber was partially filled with a model spray-dried excipient enhanced growth powder formulation with a mass of 10 mg. Device aerosolization was characterized with cascade impaction, and aerosol transmissions through oral and nasal in vitro models were assessed. Results: Best device performance was achieved when all actuation air passed through the powder chamber (no bypass flow) resulting in an aerosol mean mass median aerodynamic diameter (MMAD) <1.75 μm and a fine particle fraction (<5 μm) ≥90% based on emitted dose. Actuation with the ventilation bag enabled lung delivery efficiency through the nasal and oral interfaces to a tracheal filter of 60% or greater, based on loaded dose. In both oral and nose-to-lung (N2L) administrations, extrathoracic depositional losses were <10%. Conclusion: In conclusion, this study has proposed and initially developed an efficient inline DPI for delivering spray-dried formulations to children using positive pressure operation. Actuation of the device with positive pressure enabled effective N2L aerosol administration with a DPI, which may be beneficial for subjects who are too young to use a mouthpiece or to simultaneously treat the nasal and lung airways of older children.

Devices for Improved Delivery of Nebulized Pharmaceutical Aerosols to the Lungs

Nebulizers have a number of advantages for the delivery of inhaled pharmaceutical aerosols, including the use of aqueous formulations and the ability to deliver process-sensitive proteins, peptides, and biological medications. A frequent disadvantage of nebulized aerosols is poor lung delivery efficiency, which wastes valuable medications, increases delivery times, and may increase side effects of the medication. A focus of previous development efforts and previous nebulizer reviews, has been an improvement of the underlying nebulization technology controlling the breakup of a liquid into droplets. However, for a given nebulization technology, a wide range of secondary devices and strategies can be implemented to significantly improve lung delivery efficiency of the aerosol. This review focuses on secondary devices and technologies that can be implemented to improve the lung delivery efficiency of nebulized aerosols and potentially target the region of drug delivery within the lungs. These secondary devices may (1) modify the aerosol size distribution, (2) synchronize aerosol delivery with inhalation, (3) reduce system depositional losses at connection points, (4) improve the patient interface, or (5) guide patient inhalation. The development of these devices and technologies is also discussed, which often includes the use of computational fluid dynamic simulations, three-dimensional printing and rapid prototype device and airway model construction, realistic in vitro experiments, and in vivo analysis. Of the devices reviewed, the implementation of streamlined components may be the most direct and lowest cost approach to enhance aerosol delivery efficiency within nonambulatory nebulizer systems. For applications involving high-dose medications or precise dose administration, the inclusion of active devices to control aerosol size, guide inhalation, and synchronize delivery with inhalation hold considerable promise.

Medical devices and the pediatric population - a head-to-toe approach

Introduction: This review uses a head-to-toe approach, a standardized approach similar to the format used by clinicians during the physical examination, to highlight important differences between children, adolescents and adults. The assessment of a pediatric patient is significantly different from an adult and the heterogeneity of the pediatric population requires knowledge of the inter- and intra-subpopulation differences in growth and development for all organ systems. Areas covered: A search of the English medical literature (PubMed and EMBASE) resulted in identification and review of articles that reported medical device use in the pediatric population based on specific organ systems. The review highlights unique considerations for the pediatric population with respect to growth and development as well as important physiologic and maturational differences between children and adults pertaining to the use of medical devices. Expert opinion: Children have unique medical device needs; adult devices are often adapted or configured to address these unmet needs. It is important that clinicians, and those who manufacture and design medical devices for the pediatric population, have a heightened awareness of the varied pediatric subpopulations (neonates to adolescents) with respect to growth and development, and the adjustments needed to ensure safe and effective use of devices for their unique needs.

Use of computational fluid dynamics deposition modeling in respiratory drug delivery

INTRODUCTION

Respiratory drug delivery is a surprisingly complex process with a number of physical and biological challenges. Computational fluid dynamics (CFD) is a scientific simulation technique that is capable of providing spatially and temporally resolved predictions of many aspects related to respiratory drug delivery from initial aerosol formation through respiratory cellular drug absorption.

AREAS COVERED

This review article focuses on CFD-based deposition modeling applied to pharmaceutical aerosols. Areas covered include the development of new complete-airway CFD deposition models and the application of these models to develop a next-generation of respiratory drug delivery strategies.

EXPERT OPINION

Complete-airway deposition modeling is a valuable research tool that can improve our understanding of pharmaceutical aerosol delivery and is already supporting medical hypotheses, such as the expected under-treatment of the small airways in asthma. These complete-airway models are also being used to advance next-generation aerosol delivery strategies, like controlled condensational growth. We envision future applications of CFD deposition modeling to reduce the need for human subject testing in developing new devices and formulations, to help establish bioequivalence for the accelerated approval of generic inhalers, and to provide valuable new insights related to drug dissolution and clearance leading to microdosimetry maps of drug absorption.

Development and Evaluation of a Family of Human Face and Upper Airway Models for the Laboratory Testing of Orally Inhaled Products

Many orally inhaled products are supplied with a facemask instead of a mouthpiece, enabling aerosolized medication to be transferred from the inhaler to the lungs when the user lacks the capability to use a mouthpiece. Until recently, laboratory evaluation of an orally inhaled product-facemask was frequently undertaken by removing the facemask, treating the facemask adapter as being equivalent to a mouthpiece. Measurements of delivered drug mass were therefore subject to bias arising from the absence of dead volume, had the facemask been present. We have described the development of the Aerosol Delivery to an Anatomic Model (ADAM) infant, small child, and adult faces and upper airways, and their subsequent evaluation. Each model possesses physical features of appropriate size, and the soft tissues are also simulated. Rudimentary underlying bony structure is also present, because its purpose is only to provide support, enabling the mechanical response of the facial soft tissues when a facemask is applied to be realized. A realistic upper airway (nasopharynx for the infant model, naso- and oropharynx for the child and oropharynx for the adult models) is also incorporated, so that each model can be used to determine the mass of inhaled medication likely to penetrate as far as the lungs where therapy is intended to be applied. Measurements of the mass of pressurized metered-dose inhaler-delivered salbutamol at a filter distal to the upper airway of each model, simulating age-appropriate tidal breathing, were remarkably consistent, almost all being in the range 0.3 to 1.0 μg/kg across the model age ranges, when expressed as a fraction of body weight.

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.

SABRE: a multicentre randomised control trial of nebulised hypertonic saline in infants hospitalised with acute bronchiolitis

Aim

Acute bronchiolitis is the commonest cause for hospitalisation in infancy. Supportive care remains the cornerstone of current management and no other therapy has been shown to influence the course of the disease. It has been suggested that adding nebulised hypertonic saline to usual care may shorten the duration of hospitalisation. To determine whether hypertonic saline does have beneficial effects we undertook an open, multi-centre parallel-group, pragmatic RCT in ten UK hospitals.

Methods

Infants admitted to hospital with a clinical diagnosis of acute bronchiolitis and requiring oxygen therapy were randomised to receive usual care alone or nebulised 3% hypertonic saline (HS) administered 6-hourly. Randomisation was within 4 h of admission. The primary outcome was time to being assessed as ‘fit’ for discharge with secondary outcomes including time to discharge, incidence of adverse events together with follow up to 28 days assessing patient centred health related outcomes.

Results

A total of 317 infants were recruited to the study. 158 infants were randomised to HS (141 analysed) and 159 to standard care (149 analysed). There was no difference between the two arms in time to being declared fit for discharge (hazard ratio: 0−95, 95% CI: 0.75−1.20) nor to actual discharge (hazard ratio: 0.97, 95% CI: 0.76−1.23). There was no difference in adverse events. One infant in the HS group developed bradycardia with desaturation.

Conclusion

This study does not support the use of nebulised HS in the treatment of acute bronchiolitis over usual care with minimal handlings.

ClinicalTrials.gov registration number

NCT01469845.

Efficient Nose-to-Lung (N2L) Aerosol Delivery with a Dry Powder Inhaler

PURPOSE

Delivering aerosols to the lungs through the nasal route has a number of advantages, but its use has been limited by high depositional loss in the extrathoracic airways. The objective of this study was to evaluate the nose-to-lung (N2L) delivery of excipient enhanced growth (EEG) formulation aerosols generated with a new inline dry powder inhaler (DPI). The device was also adapted to enable aerosol delivery to a patient simultaneously receiving respiratory support from high flow nasal cannula (HFNC) therapy.

METHODS

The inhaler delivered the antibiotic ciprofloxacin, which was formulated as submicrometer combination particles containing a hygroscopic excipient prepared by spray-drying. Nose-to-lung delivery was assessed using in vitro and computational fluid dynamics (CFD) methods in an airway model that continued through the upper tracheobronchial region.

RESULTS

The best performing device contained a 2.3 mm flow control orifice and a 3D rod array with a 3-4-3 rod pattern. Based on in vitro experiments, the emitted dose from the streamlined nasal cannula had a fine particle fraction <5 μm of 95.9% and mass median aerodynamic diameter of 1.4 μm, which was considered ideal for nose-to-lung EEG delivery. With the 2.3-343 device, condensational growth in the airways increased the aerosol size to 2.5-2.7 μm and extrathoracic deposition was <10%. CFD results closely matched the in vitro experiments and predicted that nasal deposition was <2%.

CONCLUSIONS

The developed DPI produced high efficiency aerosolization with significant size increase of the aerosol within the airways that can be used to enable nose-to-lung delivery and aerosol administration during HFNC therapy.

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.

Influência do choro e de padrões respiratórios na deposição de medicação inalatória em crianças

OBJETIVO: Verificar a influência do choro e de padrões respiratórios na eficácia da terapia inalatória em crianças. FONTES DE DADOS: busca sistemática por artigos científicos referentes ao tema nas bases de dados Cochrane Controlled Trials Data Base, MedLine e Science Direct, publicadas no período de 1994 a 2009. Utilizaram-se os descritores: "choro", "inalação", "aerossol", "trabalho respiratório" e "criança", nos idiomas português e inglês. SÍNTESE DE DADOS: Foram selecionados 13 artigos, 12 em inglês e um em português. A maioria dos trabalhos apresenta os efeitos da terapia inalatória em crianças, sem discutir a influência do choro e de diferentes padrões respiratórios sobre a deposição da medicação. Estudos que fizeram essa relação verificaram que a respiração e, principalmente, o choro reduzem a quantidade de fármaco que chega às vias aéreas periféricas. Autores discutem as diferenças anatômicas e fisiológicas do sistema respiratório da criança que podem interferir na eficácia da terapia inalatória. Porém, a maioria deles não analisa a influência qualitativa e quantitativa dos padrões respiratórios e do choro sobre a mecânica pulmonar. CONCLUSÕES: O choro e os padrões respiratórios influenciam na terapia inalatória, sendo atribuída ao choro a redução significativa da deposição medicamentosa nas vias aéreas. Pouco se sabe sobre o princípio determinante para a alteração do potencial de deposição, pois são escassas as evidências sobre o tema, apesar de sua relevância no manejo de afecções pulmonares da população pediátrica.

Personalizing aerosol medicine: development of delivery systems tailored to the individual

Inhalation of drugs for therapeutic effects is not a recent innovation as illicit drugs have been ‘smoked’ for millennia. Nicotine delivery ‘devices’ in convenient packaged cartons of cigarettes are simple to use, inexpensive per dose and accessible to people of most ages and lung function, but of course their use leads to increased cancer, emphysema, heart disease and other medical and societal problems. In contrast, many inhalation pharmaceutical medical devices are expensive, nonportable, inconvenient, and/or are used improperly thus leading to poor therapeutic benefit. We review the current state of the art with respect to aerosol delivery, inhalation devices and the ability to personalize the treatment and management of lung disease. The confluence of many drivers will lead to more programmable and flexible devices in the future: the transition from the blockbuster model to customized therapy, technological advancements (e.g., smartphones) and cultural changes including social networking.

Oral inhalation therapy: meeting the challenge of developing more patient-appropriate devices

Although oral inhalers have been mass produced for more than 50 years, there is a large body of literature in which evidence has been provided that patients either misuse their inhalers inadvertently or deliberately, thereby reducing their intended efficacy or, in the worst cases, rendering them altogether ineffective. In general, inhalers are becoming increasingly complicated with the incorporation of add-on devices, miniaturized electronics and ever more complex mechanical systems that aid aerosol delivery to the lower respiratory tract and, at the same time provide user feedback. However, these benefits often come at a significant cost, and there are signs that increasing attention will need to be given to the cost-benefit equation in the future. This review explores the development of pressurized metered-dose inhalers, dry powder inhalers and devices for liquid-droplet dispersal and inhalation from the perspective of the patient, by focusing on aspects that improve user interaction. These include designed-in features, such as breath-enhanced or breath-actuated operation that interact with the breathing pattern of the user, as well as more direct feedback aids that confirm, to the patient or healthcare provider that the dose has been delivered and that the patient has inhaled.

Appropriate face models for evaluating drug delivery in the laboratory: the current situation and prospects for future advances

The laboratory evaluation of inhalers with facemasks for patient interface is so complex that testing without a facemask is generally undertaken, a practice that has been advocated in one standard. However, the facemask itself can profoundly influence medication delivery. A systematic review of the literature was undertaken to establish the development history of face models for the evaluation of facemasks used with inhalers and accessories. Initial attempts to simulate the facemask-face boundary employed a circular, firm rubber flange plate upon which the facemask was located. However, such models did not represent dead volume accurately, which is particularly important when assessing infant use. Subsequent developments included the creation of more realistic facial features, enabling the aerosol leaving the inhaler to be quantified at the facemask. In one instance (SAINT model), an anatomically correct nasopharyngeal cavity has been combined with a model face, enabling assessment of medication delivery to be extended to the lower respiratory tract. However, it is necessary either to apply sealants or to compress the facemask beyond normal to eliminate leakage with the rigid facial structure that is incomplete above the bridge of the nose. An oral-breathing infant full-face model (ADAM) intended to be used to quantify emitted mass at the patient interface incorporates flexible facial features to overcome this limitation. There is a need to extend the flexible face approach to other models that may be developed in the future for testing facemasks, whether or not they incorporate anatomically correct realizations of the upper respiratory tract.

Design of Facemasks for Delivery of Aerosol-Based Medication via Pressurized Metered Dose Inhaler with Valved Holding Chamber: Key Issues that Affect Performance

Valved holding chambers (VHCs) are widely prescribed for use with pressurized metered dose inhalers (pMDIs) for the treatment of respiratory disease by aerosol therapy. The facemask is the preferred patient interface for use by infants and small children, as well as by geriatric patients, due primarily to poor coordination skills. However, care is required in the design of the facemask-VHC system to optimize the delivery of medication. In particular, it is essential to achieve an effective mask-to-face seal and to minimize the volume of dead space. It is also important to ensure that the fit of the facemask is comfortable to the patient when applied with sufficient force to create a seal. We review each of these design principles and their application in the evolution of a range of VHCs from the same family of devices during the past fifteen years. We also examine the various methods available for evaluating VHC-facemasks as a system, recommending where future work might be directed.

The Diskus: a review of its position among dry powder inhaler devices

The use of dry powder inhalers (DPIs) to administer treatments for respiratory diseases has increased significantly in recent years. There is now a wide range of DPIs available that vary considerably in design, required operational techniques, output characteristics and drug delivery across a range of inhalation patterns. Different patient populations may find individual types of DPI easier to use correctly than others and selecting the right DPI for particular patient requirements will improve compliance with therapy. For example, some DPIs offer a greater resistance against inspirational flow rate than others which affects the total emitted dose and also fine particle mass of the aerosol released. An individual patient may therefore receive different amounts of drug when inhaling from different DPIs. Therefore, it is important that the prescriber is fully aware of the characteristics of the different types of DPI, so that he or she can prescribe the device that is most appropriate to an individual patient's needs. This review explores the characteristics of currently available DPIs and evaluates their efficacy and patient acceptability. The differences in output characteristics, ease of use and patient preferences between available devices is shown to affect treatment efficacy and patient compliance with therapy. Changing the DPI prescribed to a patient to a cheaper or generic device may therefore adversely affect disease control and thereby increase the cost of treatment.

Do patients show the same level of adherence with all dry powder inhalers?

Poor adherence with inhaled therapy presents a considerable problem. In the UK, non-adherence is estimated to occur in 10-46% of those prescribed inhaled corticosteroids and may contribute to an estimated 18-48% of asthma deaths. Before dry powder inhalers can be considered interchangeable, it is important to check that adherence is unaffected by any switching of the device dispensed to patients. Numerous studies have shown that adherence with inhaled medication is a multifactorial issue. A number of evidence-based guidelines have concluded that there is no difference in the delivery of treatments from different inhaler devices. However, many studies comparing different devices are designed to show equivalence. It is therefore difficult to determine whether the studies on which the guidelines are based were conducted with treatments already being used at the top of a dose-response curve. Furthermore, studies use selected patient populations who consent to take part and consequently receive regular contact with healthcare professionals, with emphasis on using the correct inhaler technique and on compliance. These studies do not therefore necessarily reflect real life. It is possible that patient preferences or perceptions of differences in efficacy are behind complaints when devices are switched. Patients vary in their preference for different dry powder inhalers, as shown in numerous studies of patient attitudes. There is evidence to indicate that patient claims of differences between inhalers that contain the same molecule from different manufacturers may have an objective basis. Healthcare professionals increasingly recognise the impact of patient attitudes on adherence. Accepting that patients make choices about their therapy is an integral part of achieving the partnership in management recommended by guidelines. The most effective treatment will not achieve disease control if it is not used or if it is used incorrectly. It may be short-sighted to change a device that a patient has chosen to one that is just given without consent, as this may result in poor adherence to therapy with consequent loss of control.