Asthma medication delivery: mists and myths

Currently Available Inhaled Therapies in Asthma and Advances in Drug Delivery and Devices

Medications delivered in the inhaled form remains the cornerstone of medical management of asthma. There have been considerable advances in the development of inhaled medications and devices over the past several decades. Clinicians also have access to regularly updated international guidelines for management of asthma. Despite this, a substantial proportion of children with asthma continue to have persistent poor asthma control and considerable morbidity even in well-resourced settings. The wide selection of medications and devices may complicate clinical decision making. The ideal inhaler would be one that the patient can and will use as advised. One cannot overemphasize the importance of medication adherence and a correct inhaler technique in achieving optimal asthma control. Clinicians who manage children with asthma should have a good understanding of inhaled medications and devices commercially available for the management of asthma and this would help them select the right medication and device for the right patient. This review aims to provide an overview of physiologic basis of inhaler therapy, commonly used inhaled therapies, and the advances in the field of inhaler devices including emerging technologies.

Salbutamol Transport and Deposition in the Upper and Lower Airway with Different Devices in Cats: A Computational Fluid Dynamics Approach

Simple Summary

Administration of inhaled salbutamol via metered-dose inhalers can effectively treat bronchoconstriction. Different devices are used for the delivery of this drug in cats, either in the hospital or at home, for long-term treatment. Effective drug administration may depend on the drug delivery device as well as patient cooperation. By using non-invasive computational fluid dynamics techniques, the impact of these devices on the deposition and transport of salbutamol particles in the cat airways was simulated and assessed. The results confirm a variable drug distribution depending on the device used. The percentage of particles reaching the lung was reduced when using spacers and increased when applied directly into an endotracheal tube.

Abstract

Pressurized metered-dose inhalers (pMDI) with or without spacers are commonly used for the treatment of feline inflammatory airway disease. During traditional airways treatments, a substantial amount of drugs are wasted upstream of their target. To study the efficiency of commonly used devices in the transport of inhaled salbutamol, different computational models based on two healthy adult client-owned cats were developed. Computed tomographic images from one cat were used to generate a three-dimensional geometry, and two masks (spherical and conical shapes) and two spacers (10 and 20 cm) completed the models. A second cat was used to generate a second model having an endotracheal tube (ETT) with and without the same spacers. Airflow, droplet spray transport, and deposition were simulated and studied using computational fluid dynamics techniques. Four regions were evaluated: device, upper airways, primary bronchi, and downstream lower airways/parenchyma (“lung”). Regardless of the model, most salbutamol is deposited in devices and/or upper airways. In general, particles reaching the lung varied between 5.8 and 25.8%. Compared with the first model, pMDI application through the ETT with or without a spacer had significantly higher percentages of particles reaching the lung (p = 0.006).

Use of home visits in pediatric severe asthma: randomized controlled trial

OBJECTIVE

To evaluate the effectiveness of home visits in a group of children and adolescents with severe asthma by using the inhalation technique score and adherence rates to drug treatment.

METHOD

A 12-month randomized controlled trial involving patients aged between three and 17 years under regular follow-up treatment at a pediatric pulmonology outpatient clinic of a university hospital in southeastern Brazil. A group of patients received only outpatient consultations and the other group received home visits from nurses in addition to outpatient consultations. The differences between groups were analyzed through the outcomes of inhalation technique scores and treatment adherence rate.

RESULTS

Participation of 29 patients. In the intervention group, there was a statistically significant increase in inhalation technique scores (p<0.05) and elimination of critical errors between the first and the second evaluation, and results were maintained in the third evaluation. In the control group, there were no significant changes in inhalation technique scores. Rates of adherence to drug treatment in both groups did not rise.

CONCLUSION

Home visits were effective for improving inhalation technique scores in patients with severe asthma. Brazilian Registry of Clinical Trials: RBR-8GZWZP.

Mobile applications in surgical patient health education: an integrative review

Abstract OBJECTIVE To analyze the scientific literature produced on health education through mobile applications for surgical patients. METHOD An integrative literature review performed through consultation in the following portals and/or databases: VHL; PubMed; Web of Science; Scopus; LILACS and CINAHL. The search was guided by the question: “What is the evidence on the use of mobile applications in the health education of surgical patients?” conducted from July to September 2017, including articles published from the year 2000 to 2017. RESULTS Five articles published in international journals in English with varied methodological designs were selected. Among the studies found, 60% used an educational intervention through smartphone applications in the pre and postoperative periods, and 40% of the studies had an evidence level of 2B. CONCLUSION The studies showed that the use of smartphone applications in educating and guiding surgical patients was effective. However, there is still a gap in studies which demonstrate surgical patient education through smartphone applications.

Quantitative Gd-DOTA-based aerosol deposition mapping in the lungs of asthmatic rats using 3D UTE-MRI

Asthma is a chronic respiratory disease, commonly treated with inhaled therapy. Better understanding of the mechanisms of aerosol deposition is required to improve inhaled drug delivery. Three-dimensional ultrashort echo time (UTE) MRI acquisitions at 1.5 T were combined with spontaneous nose-only inhalation of aerosolized gadolinium (Gd) to map the aerosol deposition and to characterize signal enhancement in asthmatic rat lungs. The rats were sensitized to ovalbumin (OVA) to develop asthmatic models and challenged before imaging by nebulization of OVA to trigger asthmatic symptoms. The negative controls were not sensitized or challenged by nebulization of saline. The animal lungs were imaged before and after administration of Gd-based aerosol in freely breathing rats, by using a T₁ -weighted 3D UTE sequence. A contrast-enhanced quantitative analysis was performed to assess regional concentration. OVA-sensitized rats had lower signal enhancement and lower deposited aerosol concentration. Their enhancement dynamics showed large inter-subject variability. The signal intensity was homogeneously enhanced for controls while OVA-sensitized rats showed heterogeneous enhancement. Contrast-enhanced 3D UTE was applied with aerosolized Gd to efficiently measure spatially resolved deposition in asthmatic lungs. The small administered dose (around 1 μmol/kg body weight) and the use of standard clinical MRI suggest a potential application for the exploration of asthma.

Levels of knowledge about asthma of parents of asthmatic children

Objective

To evaluate the levels of knowledge about asthma of parents of school children.

Methods

A cross-sectional study was carried out with parents of children with medical diagnosis of asthma (mild, moderate and severe), followed up at an outpatient referral center for childhood asthma in the Southern region of Brazil (Asthma Group). Parents of children with asthma in remission and healthy children were also selected (Control Group). The Newcastle Asthma Knowledge Questionnaire (NAKQ) questionnaire was applied in both groups.

Results

A total of 154 parents of children participated in the study; in that, 62 (40.26%) in the Asthma Group, and 92 (59.74%) in the Control Group, with a mean age of 35.60±10.03 years. Of these, 132 (85.7%) were female, and 72 (46.8%) parents studied up to high school. The average score of level of knowledge was 18.06±4.11 points. Only 30.5% parents had acceptable levels of knowledge about asthma, which were more prevalent in the Asthma Group than in the Control Group (41.9% versus 22.8%, p=0.01). The mean score in Newcastle Asthma Knowledge Questionnaire (NAKQ) was higher in the Asthma Group (19.32±3.92 versus 17.21±4.03, p=0.001), respectively. The parents with mild and moderate asthmatic children scored more than those of severe asthma (19.5 and 19.9 versus 18.2 points, p=0.02).

Conclusion

Most parents had an unsatisfactory level of knowledge about asthma, which reinforces the need for changes in public asthma management programs.

Assessing the viability of long-acting β2-agonists in paediatric asthma patients: a pharmacokinetic/pharmacodynamic perspective

INTRODUCTION

Long-acting β₂-agonists (LABAs) combined with inhaled corticosteroids (ICSs) are still commonly prescribed to asthmatic children. Unfortunately, pediatric LABA use is based primarily on data from adults, despite the fact that children are not simply small adults and the magnitude of changes in dose exposure and/or exposure response may not be solely reflected by differences in body weight. Areas covered: The differences in pharmacokinetics (PK) and pharmacodynamics (PD) of LABAs are described and discussed with reference children and adults. Expert opinion: Data on the PK behavior of LABAs is very limited and there is almost no data on once-daily LABAs available in the pediatric population. We do not believe that this is due to a fundamental lack of information because therapeutic response and adverse effects are more useful for the optimization of β₂-agonist treatment than measurement of plasma drug concentrations per se. Nevertheless, population PK-PD studies in children are needed according to the European rules in order to define rational, patient-tailored dosing schemes. Population PK-PD modeling and simulation using non-linear mixed effect modeling should be considered as the preferred tool to develop effective and safe dosing regimens for children because they present an opportunity to analyze sparse and unbalanced datasets, thereby minimizing the burden for each child.

Intranasally administered serelaxin abrogates airway remodelling and attenuates airway hyperresponsiveness in allergic airways disease

BACKGROUND

The peptide hormone relaxin plays a key role in the systemic hemodynamic and renovascular adaptive changes that occur during pregnancy, which is linked to its antiremodelling effects. Serelaxin (a recombinant form of human gene-2 relaxin) has been shown to inhibit lung fibrosis in various disease models and reverse airway remodelling and airway hyperresponsiveness (AHR) in allergic airways disease (AAD).

OBJECTIVE

Although continuous systemic delivery of exogenous serelaxin alleviates allergic fibrosis and AHR, more direct routes for administration into the lung have not been investigated. Thus, intranasal administration of serelaxin was evaluated for its ability to reverse airway remodelling and AHR associated with AAD.

METHODS

Female Balb/c mice were subjected to a 9-week model of chronic AAD. Subgroups of animals (n = 12/group) were then treated intranasally with serelaxin (0.8 mg/mL) or vehicle once daily for 14 days (from weeks 9-11). Saline-sensitized/challenged mice treated with intranasal saline served as additional controls. Differential bronchoalveolar lavage (BAL) cell counts, ovalbumin (OVA)-specific IgE levels, tissue inflammation, parameters of airway remodelling and AHR were then assessed.

RESULTS

Chronic AAD was associated with significant increases in differential BAL cell counts, OVA-specific IgE levels, inflammation, epithelial thickening, goblet cell metaplasia, TGF-β1 expression, epithelial Smad2 phosphorylation (pSmad2), subepithelial collagen thickness, total lung collagen concentration and AHR (all P < 0.05 vs. respective measurements from saline-treated mice). Daily intranasal delivery of serelaxin significantly diminished AAD-induced epithelial thickening, epithelial pSmad2, subepithelial and total lung collagen content (fibrosis) and AHR (all P < 0.05 vs. vehicle-treated AAD mice).

CONCLUSIONS AND CLINICAL RELEVANCE

Intranasal delivery of serelaxin can effectively reduce airway remodelling and AHR, when administered once daily. Respirable preparations of serelaxin may have therapeutic potential for the prevention and/or reversal of established airway remodelling and AHR in asthma.

Asthma myths, controversies, and dogma

Although the symptom complex we call asthma has been well described since antiquity, our understanding of the causes and therapy of asthma has evolved. Even with this evolution in our understanding, there are persistent myths (widely held but false beliefs) and dogma (entrenched beliefs) regarding the causes, classification, and therapy of asthma. It is sobering that some of the knowledge we hold dear today, will become the mythology of tomorrow.

Reversibility after inhaling salbutamol in different body postures in asthmatic children: a pilot study

RATIONALE

Pulmonary medication is mostly delivered in the form of medical aerosols to minimize systemic side effects. A major drawback of inhaled medication is that the majority of inhaled particles impacts in the oropharynx at the sharp bend of the airway. Stretching the airway by a forward leaning body posture with the neck extended ("sniffing position") may improve pulmonary deposition and clinical effects.

METHODS

41 asthmatic children who were planned for standard reversibility testing at the pulmonary function lab, alternately inhaled 200 μgr salbutamol with an Autohaler(®) in the standard or in the forward leaning body posture. Forced Expiratory Volume in 1 s (FEV1), Forced Vital Capacity (FVC), Peak Expiratory Flow (PEF), Mean Expiratory Flow at 25% of vital capacity (MEF25) and Mean Expiratory Flow at 75% of vital capacity (MEF75) were analysed.

RESULTS

The children in the forward leaning body posture group showed a significantly higher mean FEV1 reversibility than the control group after inhalation of 200 μgr salbutamol (10.2% versus 4.1%, p = 0.019). Additionally, mean MEF75 was significantly more reversible in the forward leaning body posture group versus the standard body posture group (32.2% resp. 8.9%, p = 0.013).

CONCLUSION

This pilot study showed a higher reversibility of FEV1 and MEF75 after inhaling salbutamol in a forward leaning body posture compared to the standard body posture in asthmatic children. This suggests that pulmonary effects of salbutamol can be improved by inhaling in a forward leaning body posture with the neck extended. This effect is possibly due to a higher pulmonary deposition of salbutamol and should be confirmed in a randomized controlled trial.

The acoustic features of inhalation can be used to quantify aerosol delivery from a Diskus™ dry powder inhaler

PURPOSE

Some patients are unable to generate the peak inspiratory flow rate (PIFR) necessary to de-agglomerate drug particles from dry powder inhalers (DPIs). In this study we tested the hypothesis that the acoustic parameters of an inhalation are related to the PIFR and hence reflect drug delivery.

METHODS

A sensitivity analysis of the relationship of the acoustics of inhalation to simultaneously recorded airflow, in a cohort of volunteers (n = 92) was performed. The Next Generation Impactor (NGI) was used to assess in vitro drug delivery from salmeterol/fluticasone and salbutamol Diskus™ DPIs. Fine particle fraction, FPF, (<5 μm) was measured at 30-90 l/min for 2-6 s and correlated with acoustically determined flow rate (IFRc). In pharmacokinetic studies using a salbutamol (200 μg) Diskus™, volunteers inhaled either at maximal or minimal effort on separate days.

RESULTS

PIFRc was correlated with spirometrically determined values (R (2) = 0.88). In in vitro studies, FPF increased as both flow rate and inhalation duration increased for the salmeterol/fluticasone Diskus™ (Adjusted R (2) = 0.95) and was proportional to flow rate only for the salbutamol Diskus™ (Adjusted R (2) = 0.71). In pharmacokinetic studies, blood salbutamol levels measured at 20 min were significantly lower when PIFRc was less than 60 l/min, p < 0.0001.

CONCLUSION

Acoustically-determined PIFR is a suitable method for estimating drug delivery and for monitoring inhalation technique over time.

Flunisolide for the treatment of asthma

Inhaled corticosteroids (ICSs) are recommended for treatment of persistent asthma. Several ICSs are available and delivered by a variety of devices. After the banning of chlorofluorocarbon (CFC), a formulation of hydrofluoroalkane (HFA)-flunisolide marketed with an in-built spacer has been developed, complying with the request of efficacy and safety for children and adults. It delivers an aerosol with mass median aerodynamic diameter smaller than that of the CFC-formulation (1.2 vs 3.8 m). The extrafine aerosol and the add-on spacer are peculiarities of HFA-flunisolide with respect to the traditional ICSs, assuring larger lung deposition, lower oro-pharyngeal dose and targeting small airways. HFA-flunisolide with the spacer is effective at one-third the dose of CFC-flunisolide delivered without spacer. HFA-flunisolide may be considered an effective alternative to currently available ICSs for asthma management of adult and pediatric patients 6 years of age and older.