The effects of airway disease on the deposition of inhaled drugs.

INTRODUCTION: The deposition of inhaled medications is the first step in the pulmonary pharmacokinetic process to produce a therapeutic response. Not only lung dose but more importantly the distribution of deposited drug in the different regions of the lung determines local bioavailability, efficacy, and clinical safety. Assessing aerosol deposition patterns has been the focus of intense research that combines the fields of physics, radiology, physiology, and biology. AREAS COVERED: The review covers the physics of aerosol transport in the lung, experimental, and in-silico modeling approaches to determine lung dose and aerosol deposition patterns, the effect of asthma, chronic obstructive pulmonary disease, and cystic fibrosis on aerosol deposition, and the clinical translation potential of determining aerosol deposition dose. EXPERT OPINION: Recent advances in in-silico modeling and lung imaging have enabled the development of realistic subject-specific aerosol deposition models, albeit mainly in health. Accurate modeling of lung disease still requires additional refinements in existing imaging and modeling approaches to better characterize disease heterogeneity in peripheral airways. Nevertheless, recent patient-centric innovation in inhaler device engineering and the incorporation of digital technology have led to more consistent lung deposition and improved targeting of the distal airways, which better serve the clinical needs of patients.

Improving asthma outcomes: Clinicians' perspectives on peripheral airways.

Disease of the peripheral (or small) airways is fundamental in asthma, being closely related to symptoms (or lack of control of them), airway hyperresponsiveness, spirometric abnormalities, risk of loss of control, or exacerbations and inflammation. Current technology now allows routine measurement of peripheral airway function. Having a working concept of peripheral airways disease in asthma is arguably very useful to clinicians and beneficial to patients because it allows a more comprehensive assessment of asthma severity (rather than just symptoms alone, which is the norm), tracking of progress or deterioration, and assessing response to treatment. Oscillometry is a sensitive way to monitor the peripheral airways, whereas multiple breath nitrogen washout parameters are excellent measures of future risk. In the longer term, physiologic measurements will be crucial in research to define causes and find new disease-modifying treatments.

Development and evaluation of a tool to optimise inhaler selection prior to hospital discharge following an exacerbation of COPD.

Introduction: Rates of mortality and re-admission after a hospitalised exacerbation of COPD are high and resistant to change. COPD guidelines do not give practical advice about the optimal selection of inhaled drugs and device in this situation. We hypothesised that a failure to optimise inhaled drug and drug delivery prior to discharge from hospital after an exacerbation would be associated with a modifiable increased risk of re-admission and death. We designed a study to 1) develop a practical inhaler selection tool to use at the point of hospital discharge and 2) implement this tool to understand the potential impact on modifying inhaler prescriptions, clinical outcomes, acceptability to clinicians and patients, and the feasibility of delivering a definitive trial to demonstrate potential benefit. Methods: We iteratively developed an inhaler selection tool for use prior to discharge following a hospitalised exacerbation of COPD using surveys with multiprofessional clinicians and a focus group of people living with COPD. We surveyed clinicians to understand their views on the minimum clinically important difference (MCID) for death and re-admission following a hospitalised exacerbation of COPD. We conducted a mixed-methods implementation feasibility study using the tool at discharge, and collated 30- and 90-day follow-up data including death and re-admissions. Additionally, we observed the tool being used and interviewed clinicians and patients about use of the tool in this setting. Results: We completed the design of an inhaler selection tool through two rounds of consultations with 94 multiprofessional clinicians, and a focus group of four expert patients. Regarding MCIDs, there was majority consensus for the following reductions from baseline being the MCID: 30-day readmissions 5-10%, 90-day readmissions 10-20%, 30-day mortality 5-10% and 90-day mortality 5-10%. 118 patients were assessed for eligibility and 26 had the tool applied. A change in inhaled medication was recommended in nine (35%) out of 26. Re-admission or death at 30 days was seen in 33% of the switch group and 35% of the no-switch group. Re-admission or death at 90 days was seen in 56% of the switch group and 41% of the no-switch group. Satisfaction with inhalers was generally high, and switching was associated with a small increase in the Feeling of Satisfaction with Inhaler questionnaire of 3 out of 50 points. Delivery of a definitive study would be challenging. Conclusion: We completed a mixed-methods study to design and implement a tool to aid optimisation of inhaled pharmacotherapy prior to discharge following a hospitalised exacerbation of COPD. This was not associated with fewer re-admissions, but was well received and one-third of people were eligible for a change in inhalers.

Demystifying Dry Powder Inhaler Resistance with Relevance to Optimal Patient Care.

The selection of an inhaler device is a key component of respiratory disease management. However, there is a lack of clarity surrounding inhaler resistance and how it impacts inhaler selection. The most common inhaler types are dry powder inhalers (DPIs) that have internal resistance and pressurised metered dose inhalers (pMDIs) that use propellants to deliver the drug dose to the airways. Inhaler resistance varies across the DPIs available on the market, depending largely on the design geometry of the device but also partially on formulation parameters. Factors influencing inhaler choice include measures such as flow rate or pressure drop as well as inhaler technique and patient preference, both of which can lead to improved adherence and outcomes. For optimal disease outcomes, device selection should be individualised, inhaler technique optimised and patient preference considered. By addressing the common clinically relevant questions, this paper aims to demystify how DPI resistance should guide the selection of the right device for the right patient.

Selection of the right inhaler is important to ensure that patients with respiratory diseases get the most benefit from their treatment. Dry powder inhalers and pressurised metered dose inhalers are the most common inhaler types. Pressurised metered dose inhalers use propellants to deliver the drug to the lungs. In contrast, dry powder inhalers deliver the drug to the lungs by having internal resistance. This restricts the flow of air through the inhaler. As the patient inhales through the inhaler, the resistance against the air flow generates the power to separate the drug molecules and carry them to the lungs. While there are many factors to be considered for inhaler selection, there is often confusion around how resistance should guide selection of inhaler. With low-resistance devices, patients must inhale faster to generate the power to separate the drug molecules, which may be difficult in patients with poor lung function. With high-resistance devices, patients do not need to inhale as fast to separate the drug, and most patients can effectively use the inhaler. This article addresses the common clinically relevant questions to clarify how the internal resistance of the inhaler should be used to help guide the selection of the right device for the right patient.

A narrative review on the Synchrobreathe™: A novel breath-actuated pressurised metered-dose inhaler for the treatment of obstructive airway diseases.

Pressurised metered-dose inhalers (pMDIs) and dry powder inhalers (DPIs), are widely used to deliver drugs for the treatment of asthma and chronic obstructive pulmonary disease (COPD). Incorrect use of inhalers is one of the main obstacles to achieving better clinical control. Indeed, with pMDIs, patients fail to synchronise actuation with inhalation due to a lack of coordination and with DPIs insufficient inspiratory effort compromises drug deposition in lungs. More than 50% of patients desire to switch their pMDIs and DPIs for a better device. This led to the development of pressurised breath-actuated inhalers (BAIs) with the aim of combining the beneficial features of pMDIs and DPIs and mitigating their problems. BAIs, e.g., Synchrobreathe™, are designed such that they are activated by a low inhalation effort and mechanically actuate the dose in synchrony to inspiration, thereby resolving the need to coordinate actuation with inspiration. BAIs have advantages, including ease of use, high lung deposition of medication, and greater patient preference. We discussed the design features, operating procedure, and clinical evidence of the Synchrobreathe™ device (Cipla Ltd, India), a BAI available with a wide range of drug combinations. Studies have shown that a higher number of patients (68.19%) used the Synchrobreathe™ without any error than the pMDI (56.21%), and that the vast majority of them (92%) found it easy to understand and use. The Synchrobreathe™ is an innovative, easy-to-use inhaler that may overcome many limitations associated with pMDIs and DPIs, thus potentially improving management of obstructive airway diseases and patients' quality of life.

Small airways in asthma: Pathophysiology, identification and management.

Background: The aim of this review is to summarize the current evidence regarding small airway disease in asthma, focusing on recent advances in small airway pathophysiology, assessment and therapeutic implications. Methods: A search in Medline was performed, using the keywords "small airways", "asthma", "oscillometry", "nitrogen washout" and "imaging". Our review was based on studies from adult asthmatic patients, although evidence from pediatric populations is also discussed. Results: In asthma, inflammation in small airways, increased mucus production and airway wall remodelling are the main pathogenetic mechanisms of small airway disease. Small airway dysfunction is a key component of asthma pathophysiology, leading to increased small airway resistance and airway closure, with subsequent ventilation inhomogeneities, hyperresponsiveness and airflow limitation. Classic tests of lung function, such as spirometry and body plethysmography are insensitive to detect small airway disease, providing only indirect measurements. As discussed in our review, both functional and imaging techniques that are more specific for small airways, such as oscillometry and the multiple breath nitrogen washout have delineated the role of small airways in asthma. Small airways disease is prevalent across all asthma disease stages and especially in severe disease, correlating with important clinical outcomes, such as asthma control and exacerbation frequency. Moreover, markers of small airways dysfunction have been used to guide asthma treatment and monitor response to therapy. Conclusions: Assessment of small airway disease provides unique information for asthma diagnosis and monitoring, with potential therapeutic implications.

The Role of Viral Infections on Severe Asthma Exacerbations: Present and Future

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