Insights into Inhalation Drug Disposition: The Roles of Pulmonary Drug-Metabolizing Enzymes and Transporters

The past five decades have witnessed remarkable advancements in the field of inhaled medicines targeting the lungs for respiratory disease treatment. As a non-invasive drug delivery route, inhalation therapy offers numerous benefits to respiratory patients, including rapid and targeted exposure at specific sites, quick onset of action, bypassing first-pass metabolism, and beyond. Understanding the characteristics of pulmonary drug transporters and metabolizing enzymes is crucial for comprehending efficient drug exposure and clearance processes within the lungs. These processes are intricately linked to both local and systemic pharmacokinetics and pharmacodynamics of drugs. This review aims to provide a comprehensive overview of the literature on lung transporters and metabolizing enzymes while exploring their roles in exogenous and endogenous substance disposition. Additionally, we identify and discuss the principal challenges in this area of research, providing a foundation for future investigations aimed at optimizing inhaled drug administration. Moving forward, it is imperative that future research endeavors to focus on refining and validating in vitro and ex vivo models to more accurately mimic the human respiratory system. Such advancements will enhance our understanding of drug processing in different pathological states and facilitate the discovery of novel approaches for investigating lung-specific drug transporters and metabolizing enzymes. This deeper insight will be crucial in developing more effective and targeted therapies for respiratory diseases, ultimately leading to improved patient outcomes.

Preparation and evaluation of spray-dried inhalable microparticles from carrier mixtures

The formulation of microparticles composed of a mixture of carriers represents an innovative approach for lung drug delivery of dry powder. The carriers used can significantly influence the properties of the microparticles, such as size, shape, surface area, hygroscopicity, or aggregation, thus improving the aerosolization of the drugs after inhalation. The properties mentioned above are crucial for effective  pulmonary  therapy. The  combination of carriers of a carbohydrate nature and gelling agents is advantageous for controlled drug release. The experimental work aimed to prepare by spray drying and subsequently evaluate ten batches of microparticles composed of sugar-based carriers (mannitol, maltodextrin, dextran) and gelling polymers (chitosan, chondroitin sulfate) and to select a suitable combination for follow-up experimental work aimed at drug incorporation into the microparticle matrix. The most suitable parameters were exhibited by batches whose aerodynamic diameter was close to 5 µm, particles prepared from a combination of mannitol and dextran, chitosan and chondroitin, or maltodextrin and chondroitin. These batches also showed the highest fine particle fraction value (> 43%). From a processability point of view, the batch with maltodextrin and chondroitin is preferable due to the lower viscosity of the dispersion and the more regular shape of the final microparticles.

Preparation and evaluation of spray-dried inhalable microparticles from carrier mixtures

The formulation of microparticles composed of a mixture of carriers represents an innovative approach for lung drug delivery of dry powder. The carriers used can significantly influence the properties of the microparticles, such as size, shape, surface area, hygroscopicity, or aggregation, thus improving the aerosolization of the drugs after inhalation. The properties mentioned above are crucial for effective  pulmonary  therapy. The  combination of carriers of a carbohydrate nature and gelling agents is advantageous for controlled drug release. The experimental work aimed to prepare by spray drying and subsequently evaluate ten batches of microparticles composed of sugar-based carriers (mannitol, maltodextrin, dextran) and gelling polymers (chitosan, chondroitin sulfate) and to select a suitable combination for follow-up experimental work aimed at drug incorporation into the microparticle matrix. The most suitable parameters were exhibited by batches whose aerodynamic diameter was close to 5 µm, particles prepared from a combination of mannitol and dextran, chitosan and chondroitin, or maltodextrin and chondroitin. These batches also showed the highest fine particle fraction value (> 43%). From a processability point of view, the batch with maltodextrin and chondroitin is preferable due to the lower viscosity of the dispersion and the more regular shape of the final microparticles.

Impact of Post-Visit Outreach on Inhaled Corticosteroid Refill Persistence in Children and Young Adults With Asthma

BACKGROUND

Inhaled corticosteroids (ICSs) are a fundamental pillar of most regimens for long-term control of persistent asthma. Poor adherence to ICS medication is a common problem in the asthma population that can lead to poor asthma control. We hypothesized that conducting a follow-up telephone call after general pediatric clinic visits for asthma would improve refill persistence.

METHODS

We conducted a prospective cohort analysis of pediatric and young adult subjects followed in our pediatric primary care clinic for asthma on ICS medication found to have poor ICS refill persistence. This cohort received a follow-up telephone outreach call 5-8 weeks after the clinic visit. The primary outcome measure was refill persistence with regard to ICS therapy.

RESULTS

There were 289 subjects who met the inclusion criteria and did not meet any exclusion criteria for the study (n = 131 in the primary cohort, n = 158 in the post-COVID cohort). The mean ICS refill persistence increased significantly for subjects in the primary cohort (39.4 ± 30.8% post intervention vs 32.4 ± 19.7% pre intervention) (P = .02) but not in the post-COVID cohort (36.4 ± 25.6% post intervention vs 38.9 ± 21.0% pre intervention) (P = .26). There was not a statistically significant change in hospitalizations after the intervention in either the primary or the post-COVID cohorts (P = .08 and .07, respectively). Systemic corticosteroid courses and emergency department visits decreased significantly post intervention (P = .01 and P = .004, respectively) in the primary group but not in the post-COVID group (P = .75 and P = .16, respectively).

CONCLUSIONS

These results suggest that telephone outreach after out-patient clinic visits for asthma may have short-term benefit in ICS refill persistence; however, the effect size was small.

Effects of Lavender Essential Oil Inhalation on the Welfare and Meat Quality of Fattening Heavy Pigs Intended for Parma Ham Production

We assessed the effects of inhalation administration of lavender essential oil (LEO) either once (L1) or twice (L2) a day on animal welfare indicators, carcass and meat quality of Italian heavy pigs. Pigs (n = 108) were allotted to three experimental groups (control -C-, L1 and L2) and lavender was administered, via a vaporizer device, to the treated groups during the entire fattening-finishing period (79-160 kg BW). Tail lesion severity was reduced in L1 at the end of the trial compared to the other groups (p < 0.05). Body lesion counts, however, were higher in L2 than in C (p < 0.05), resulting in a more severe overall damage classification (p < 0.01). At slaughter, no differences were observed in carcass traits or blood stress indicators, only minor differences were observed in meat quality, and no LEO residual was found in fat or lean tissues, highlighting the preserved suitability of thighs for the dry curing process. While it was not possible to conclude on the ability to improve animal welfare of vaporized LEO in this production phase, the absence of adverse effects on meat quality and the discrepancies observed regarding the body lesions in L1 and L2 make further studies on behavioral aspects and the method of administration (route, frequency) of the product desirable.

Agarwood essential oil inhalation exerts antianxiety and antidepressant effects via the regulation of Glu/GABA system homeostasis

Depression and anxiety are common diseases that endanger the physical and mental health of individuals. Agarwood incense inhalation has been used as a traditional Chinese medicine for relaxation and to improve sleep for centuries. In a previous study by the authors it was demonstrated that agarwood essential oil (AEO) injection exerted anxiolytic and antidepressant effects. Therefore the present study further investigated the anxiolytic and antidepressant effects of AEO inhalation on anxiolytic mice induced by M-chlorophenylpiperazine and depressive mice induced by chronic unpredictable mild stress. The results demonstrated that AEO exerted a significant anxiolytic effect, whereby autonomous movements were inhibited during the light dark exploration test and open field test. Furthermore, the tail suspension test and the forced swimming test demonstrated that AEO also exerted an antidepressant effect, whereby the immobility times were decreased. Moreover, AEO was determined to increase the levels of 5-hydroxytryptamine, γ-aminobutyric acid (GABA) A receptor (GABA_A) and glutamate (Glu) in anxiolytic mice and inhibit the levels of GABA_A and Glu in depressive mice. Further investigations into how AEO affected the Glu/GABA system demonstrated that AEO markedly increased the protein expression levels of GABA transaminase (GABAT), glutamate metabotropic receptor 5 (GRM5), glutamate ionotropic receptor AMPA type subunit 1 (GluR1) and vesicular glutamate transporter 1 (VGluT1). Furthermore, AEO reduced the expression levels of GABAT, glutamate ionotropic receptor NMDA type subunit 2B and GRM5, and enhanced the expression levels of GluR1 and VGluT1. These results demonstrated that AEO potentially possesses antianxiety and antidepressant properties. The present study determined that the mechanism was related to the regulation of Glu/GABA neurotransmitter system homeostasis.

Optimization of spray-dried porous microparticles preparation for pulmonary delivery

Inhalation administration of dry powder particles is a common application route to achieve local and systemic drug effects. For pulmonary diseases, the deposition of drugs at the site of action is desirable. Thus, the parameters of the inhaled particles, especially their size, shape, or aerosolization, are essential for effective treatment. Suitable parameters can be achieved by choice of preparation method or excipients (carriers, porogens, or aerosolizing agents). This experiment aimed to prepare 11 batches of powder mixtures by spray drying, which differed in the carrier used and the amount of leucine or porogen. The aim was to optimize the formulation for drug binding concerning the requirements for pulmonary administration. The prepared particles were evaluated in terms of morphology, flow properties, porosity, and geometric and aerodynamic diameter. It was found that with increasing concentration of leucine, the bulk density of the particles decreased while the FPF value increased. Similarly, there was a decrease in MMAD. The batch containing 15% leucine was the most suitable. In determining the optimum porogen concentration for mannitol particles, the batch with its 1% gave the best results due to its adequate particle size compared to the other batches (MMAD 5.92 ± 1.32 μm), suitable porosity, and particle morphology. Thus, to formulate drug-loaded particles, it would be advisable to reduce the aerodynamic diameter of the particles, e.g., by spray drying process parameters.

Effects of inhaled furosemide on dyspnea and pulmonary function in people with COPD: A literature review

PURPOSE

To determine whether inhaled furosemide can be effectively used in patients with chronic obstructive pulmonary disease (COPD) to improve feelings of dyspnea and improve pulmonary function values.

METHODS

This literature review was conducted using randomized control trials and a literature review in which the participants consisted of or included patients with COPD receiving inhaled furosemide as a potential treatment option for their dyspnea and low pulmonary function values.

RESULTS

Searches in four databases and secondary sources using five key terms yielded 83 unduplicated articles. Ultimately, four studies, one of which was a literature review, were included which studied the short-term result of inhaled furosemide on dyspnea and pulmonary function values. All studies measured dyspnea as an outcome and three found a statistically significant improvement in patient reported symptoms. Pulmonary function values were measured in all studies which all found improvements.

CONCLUSION

The effect of inhaled furosemide on the dyspnea and pulmonary function values in people with COPD remains uncertain, and questions have emerged regarding the long-term impact on these patients. While this therapy is promising for dyspnea relief and improvement of pulmonary function values in people with COPD, further consideration and additional data still need to be gathered.

Real-Time Analysis of Dry-Side Nebulization With Heated Wire Humidification During Mechanical Ventilation

BACKGROUND

Recent observational studies of nebulizers placed on the wet side of the humidifier suggest that, after some time, considerable condensation can form, which triggers an occlusion alarm. In the current study, an inline breath-enhanced jet nebulizer was tested and compared in vitro with a vibrating mesh nebulizer on the humidifier dry-inlet side of the ventilator circuit.

METHODS

Two duty cycle breathing patterns were tested during continuous infusion (5 or 10 mL/h) with and without dynamic changes in infusion flow and duty cycle, or bolus delivery (3 or 6 mL) of radiolabeled saline solution. Inhaled mass (IM) was measured by a real-time ratemeter (µCi/min) and analyzed by multiple linear regression.

RESULTS

During simple continuous infusion, IM increased linearly for both nebulizer types. IM variability was attributable to the duty cycle (P < .001) (34%) and infusion flow (P < .001) (32%) but independent of nebulizer technology (P = .38) (7%). Dynamic continuous infusion studies that simulate clinical scenarios with ventilator and pump flow changes demonstrated a linear increase in the rate of aerosol that was dependent on pump flow (P < .001) (63%) and minimally dependent on the duty cycle (P = .003) (8%). During bolus treatments, IM increased linearly to plateau. IM variability was attributable to the duty cycle (P < .001) (40%) and residual radioactivity in the nebulizer (P < .001) (20%). Separate analysis revealed that the vibrating mesh nebulizer residual volume contributed 16% of the variability and inline breath-enhanced jet nebulizer contributed 5%. IM variability was independent of bolus volume (P = .82) (1%). System losses were similar (the inline breath-enhanced jet nebulizer: 32% residual in nebulizer; the vibrating mesh nebulizer: 34% in circuitry).

CONCLUSIONS

Aerosol delivery during continuous infusion and bolus delivery was comparable between the inline breath-enhanced jet nebulizer and the vibrating mesh nebulizer, and was determined by pump flow and initial ventilator settings. Further adjustments in ventilator settings did not significantly affect drug delivery. Expiratory losses predicted by the duty cycle were reduced with placement of the nebulizer near the ventilator outlet.

Continuous infusion aerosol delivery of prostacyclins during mechanical ventilation: challenges, limitations, and recent advances

INTRODUCTION

Critically ill mechanically ventilated patients routinely receive aerosol delivery of epoprostenol by continuous infusion of the nebulizer by syringe pump. This procedure is 'off-label' as no FDA approved drug presently exists. Without standardized protocols, therapy is based on prior experience with bronchodilators, limited studies of delivery systems and anecdotal clinical trials. Current protocols based upon patient body weight and drug concentration determines the infusion rate of drug dose delivered to the nebulizer , which is only distantly related to dose delivered to the lung and may be altered by many factors.

AREAS COVERED

This paper reviews the background of this technique as well as current methods of managing drug delivery, technical challenges, and limitations. A recent advance in aerosol laboratory bench testing, using radiolabeled aerosols, is presented to reveal important factors defining delivery.

EXPERT OPINION

Off-label use of continuously nebulized prostacyclin in the ICU lacks the support of large clinical trials needed for FDA clearance. However, comprehensive bench studies afford the potential for clinicians to better understand and manage therapy at a level above simple dosing of the nebulizer by body weight. New research techniques are enhancing our basic comprehension of the interaction between aerosol devices and the mechanical ventilator.

Inhalation Administration of Agarwood Incense Rescues Scopolamine-Induced Learning and Memory Impairment in Mice

Background: Agarwood, a type of herbal medicine widely used in Asian countries, is noted in traditional medicine for its intelligence-enhancing effects. Agarwood incense is traditionally administered by oral and nasal inhalation. To verify whether agarwood incense can exert its intelligence-enhancing effects in this way to rescue learning and memory impairment, typical clinical manifestations of dementia, we conducted a set of behavioral tests related to learning and memory.

Methods: C57BL/6 mice were divided into six groups. In addition to the control and model groups, we added a donepezil treatment group to evaluate the effect of three different agarwood administration doses. After a week of administration, scopolamine was injected 30 min before each behavioral test to create a learning and memory impairment model. A series of behavioral tests [the Morris water maze test (MWM), the novel object recognition test (NOR), and the step-down test (SDT)] were used to assess their learning ability, as well as their spatial and recognition memory.

Results: After scopolamine injection, the model group showed significant learning and memory impairment (i.e., longer latencies, lower crossing times, and lesser distance travelled in the target quadrant in MWM; a lower recognition index in NOR; and longer latencies and higher error times in SDT). The other four treatment groups all showed improvements in these indicators, and the overall therapeutic effect of agarwood was superior.

Conclusion: The inhalation administration of agarwood can significantly improve the learning and memory impairment caused by scopolamine in mice, and the therapeutic effect varied between doses.

Estimation of the cost of influenza antiviral medication guidance or support provided by healthcare professionals: a questionnaire survey in Japan

AIMS

To estimate the cost of antiviral medication guidance and/or support from the perspective of healthcare professionals by administration route (oral or inhalant).

METHODS

An online survey (December 2020) was conducted among physicians, pharmacists, and certified care workers. Those aged 20-64 years working in workplaces with experience of prescribing (physicians) or dispensing (pharmacists) antivirals for influenza, or having care service recipients who took antivirals (certified care workers) since October 2018, were selected through screening questions. The time required for guidance and/or support for drug administration was asked, and its monetary value was calculated by applying the Japanese average wage. Respondents who had a fear of infection while providing guidance and/or support were asked about the monetary value of this fear; the cost of fear was estimated from their responses and the percentage who reported such a fear.

RESULTS

Responses were collected from 1,000 physicians, 1,000 pharmacists, and 642 certified care workers. The cost of the time for guidance and/or support in the entire workplace was estimated as JPY 244 (USD 2.14, as of October 2021) for oral antivirals and JPY 289 for inhalants among physicians, JPY 260 and JPY 428 among pharmacists, and JPY 555 and JPY 557 among certified care workers. The cost of fear was estimated to be JPY 965 for oral and JPY 1,361 for inhalants among physicians, JPY 756 and JPY 2,711 among pharmacists, and JPY 2,419 and JPY 2,837 among certified care workers.

LIMITATIONS

Respondents might not be representative of Japanese society. The reliability of the results depends on whether the respondents accurately understood the questions and their truthfulness.

CONCLUSIONS

Higher costs for guidance and/or support were suggested for inhalant antivirals in physicians and pharmacists compared to oral antivirals. For certified care workers, almost no difference in costs was suggested between administration routes.

Real-Time In Vitro Assessment of Aerosol Delivery During Mechanical Ventilation

Background: A new real-time method for assessing factors determining aerosol delivery is described.

Methods: A breath-enhanced jet nebulizer operated in a ventilator/heated humidifier system was tested during bolus and continuous infusion aerosol delivery. ^99mTc (technetium)/saline was either injected (3 or 6 mL) or infused over time into the nebulizer. A shielded gamma ratemeter was oriented to count radioaerosol accumulating on an inhaled mass (IM) filter at the airway opening of a test lung. Radioactivity measured at 2–10-minute intervals was expressed as % nebulizer charge (bolus) or % syringe activity per minute infused. All circuit parts were measured and imaged by gamma camera to determine mass balance.

Results: Ratemeter activity quantitatively reflected immediate changes in IM: 3 and 6 mL bolus IM% = 16.1 and 18.8% in 6 and 14 minutes, respectively; infusion IM% = 0.64 + 0.13 (run time, min), R² 0.999. Effect of nebulizer priming and system anomalies were readily detected in real time. Mass balance (basis = dose infused in 90 minutes): IM 39.2%, breath-enhanced jet nebulizer residual 35.5%, circuit parts including humidifier 23.4%, and total recovery 98.1%. Visual analysis of circuit component images identified sites of increased deposition.

Conclusion: Real-time ratemeter measurement with gamma camera imaging provides operational feedback during in vitro testing procedures and yields a detailed analysis of the parameters influencing drug delivery during mechanical ventilation. This method of analysis facilitates assessment of device function and influence of circuit parameters on drug delivery.

Factors Determining Continuous Infusion Aerosol Delivery During Mechanical Ventilation

BACKGROUND

Continuous nebulization of prostacyclins and albuterol by infusion pump during mechanical ventilation evolved as a popular off-label treatment for severe hypoxemic respiratory failure and asthma. Most institutions use a vibrating mesh nebulizer. A new breath-enhanced jet nebulizer is a potential alternative. This study was designed to compare these devices to better define factors influencing continuous infusion aerosol delivery. Device function, ventilator settings, and infusion pump flow were studied in vitro.

METHODS

Using a bench model of adult mechanical ventilation, radiolabeled saline was infused at 6 flows (1.5-12 mL/h) into test nebulizers; 4 examples of each were used in rotation to test device reproducibility. Four breathing patterns with duty cycles (percentage of inspiratory time) ranging from 0.13 to 0.34 were tested. The vibrating mesh nebulizer was installed on the "dry" side of the heated humidifier (37°C). The breath-enhanced jet nebulizer, installed on the "wet" side, was powered by air at 3.5 L/min and 50 psi. Infusion time was 1 h. Inhaled mass of aerosol was collected on a filter at the airway opening. Inhaled mass was expressed as the percentage of the initial syringe radioactivity delivered per hour. Radioactivity deposited in the circuit was measured with a gamma camera. Data were analyzed with multiple linear regression.

RESULTS

Variation in inhaled mass was significantly explained by pump flow and duty cycle (R² 0.92) and not by nebulizer technology. Duty cycle effects were more apparent at higher pump flow. Vibrating mesh nebulizers failed to nebulize completely in 20% of the test runs. Mass balance indicated that vibrating mesh nebulizers deposited 15.3% in the humidifier versus 0.2% for breath-enhanced jet nebulizer.

CONCLUSIONS

Aerosol delivery was determined by infusion pump flow and ventilator settings with comparable aerosol delivery between devices. The breath-enhanced jet nebulizer was more reliable than the vibrating mesh nebulizer; 10-12 mL/h was the maximum infusion flow for both nebulizer technologies.

Estimation of the value of convenience in taking influenza antivirals in Japanese adult patients between baloxavir marboxil and neuraminidase inhibitors using a conjoint analysis

AIMS

Estimating the monetary value of the convenience of using influenza antivirals approved in Japan from a patient perspective using a conjoint analysis.

METHODS

An online survey (August 2020) was performed on individuals aged 20-64 years living in Japan who had taken oral or inhalant antivirals for influenza treatment in the 2018/19 or 2019/20 seasons. Efficacy and safety were assumed to be equivalent among the antivirals. The attributes for the conjoint analysis included route (oral or inhalant), duration, frequency of administration, and out-of-pocket expenses. A conditional logit model was applied as a baseline model. The monetary value of each attribute was calculated by comparing the same utility of the linearly interpolated level of the out-of-pocket attribute. Another survey to determine the experiences of the latest antiviral intake was also conducted on the same respondents.

RESULTS

Of the respondents, 1,550 were men and 1,587 were women. The monetary value for oral antivirals was estimated to be higher, saving JPY 741 (USD 7.06, as of August 2020), compared with inhalant. Regarding the length and frequency of administration, five days corresponds to an increase of JPY 2,072, compared with one day, and twice a day corresponds to a JPY 574 increase compared to once a day.

CONCLUSIONS

The results suggest that - among the antivirals approved in Japan - the monetary value of the utility is the highest in the single dose oral antiviral, baloxavir marboxil (baloxavir). Although the drug cost was highest in baloxavir among the brand antivirals, the difference in the value of utility for influenza patient was estimated to be larger than the difference in the drug costs.

LIMITATIONS

Although individuals with diverse attributes from all over the country were included in the survey, they are not necessarily a representative population of the Japanese society.

Inhalation with intravenous loading dose of colistin in critically ill patients with pneumonia caused by carbapenem-resistant gram-negative bacteria

Background:

Despite the increasing use of colistin in clinical practice, the optimal dosing, and administration route have not been established. This study aimed to evaluate the clinical outcome and safety of intravenous (IV) colistin with a loading dose (LD) and adjunctive aerosolized (AS) colistin administration in critically ill patients with hospital-acquired pneumonia (HAP) or ventilator-associated pneumonia (VAP) caused by carbapenem-resistant gram-negative bacteria (CRGNB).

Methods:

We retrospectively reviewed 191 critically ill patients who received colistin for the treatment of HAP or VAP caused by CRGNB. Patients were divided into three groups: non-LD IV (patients received only IV colistin without LD), LD IV (patients received only IV colistin with LD), and AS–LD (patients received IV colistin with LD and adjunctive AS colistin).

Results:

There was no difference in clinical response between the three groups. However, the rate of microbiological eradication was significantly higher in the AS–LD group (60%) than in the non-LD IV (31%), and LD IV (33%) groups (p = 0.010). Patients treated with adjunctive AS colistin in combination with LD IV had significantly lower 30-day mortality rates than patients treated with IV colistin alone (p = 0.027). After adjusting for potential confounding factors, adjunctive AS colistin was still significantly associated with lower mortality (adjusted OR 0.338, CI 95% 0.132–0.864, p = 0.024). However, nephrotoxicity did not change according to the use of LD regimen and AS colistin administration (p = 0.100).

Conclusions:

Adjunctive AS colistin in combination with IV colistin with LD was related to an improved 30-day mortality and microbiological outcome without an increase in nephrotoxicity in critically ill patients with HAP and VAP caused by CRGNB.

The reviews of this paper are available via the supplemental material section.

Understanding the Knowledge Gap and Assessing Comfort Level among Healthcare Professionals Who Provide Inhaler Education

Inhaled medications play a pivotal role in the management of COPD and asthma. Provider knowledge and ability to teach various devices is paramount as poor inhaler technique directly correlates with worse disease control. The goal of our survey was to assess the knowledge and comfort level with various inhaled devices among providers involved in patient inhaler education. We constructed a 20-question survey consisting of a five-question Likert scale-based comfort assessment and a 15-question multiple-choice inhaler knowledge test that was distributed both internally and nationwide. Groups surveyed included internal medicine residents, family medicine residents, pulmonary fellows, respiratory therapists, nursing staff, and pharmacists. A total of 557 providers responded to the survey. The overall correct response rate among all respondents was only 47%. There was no significant difference between correct response rates among prescribers (internal medicine residents, family medicine residents, and pulmonary fellows) and non-prescribers (respiratory therapists, nursing staff, and pharmacists), 47% and 47%, respectively (p = 0.6919). However, respiratory therapists had the overall highest correct response rate of 85%. Over 72% of respondents indicated that they educate patients on inhaler technique as part of their clinical duties. Furthermore, the correct response rates for various inhaler devices varied with 55% among metered dose inhalers, 52% among dry powder inhalers, and 34% among soft-mist inhalers. Our study reveals that there is a continued need for education on the subject of inhaler devices among providers given their overall poor knowledge, particularly in an era of fast-changing inhaler devices. We continue without knowing what we teach.

In vitro drug delivery performance of five valved holding chambers with and without facemasks

BACKGROUND

Valved holding chambers (VHCs) are essential for efficient pulmonary delivery of inhaled medication in preschool children. The numerous devices in the market vary in material, aerodynamic characteristics, volume, valve properties, and mask design. Drug delivery is affected by the VHC characteristics as well as by the age and breathing pattern of the child.

METHODS

We measured the drug delivery efficacy of five VHCs widely available in the market, evaluated the effect of facemasks and tested the differences between manufacturing lots. A breathing simulator was used to mimic normal (respiratory rate [RR] 25/minute and tidal volume (V_T ) 200 mL) and obstructive (RR 50/minute and V_T 50 mL) breathing of infants and toddlers.

RESULTS

Salbutamol output was significantly higher with a normal breathing pattern compared to the obstructive breathing pattern in most VHCs. Without masks, the differences in the median in vitro filter doses of salbutamol were mainly from 2 to 10-fold among different types of VHCs. With masks, there was a greater than 20-fold difference in drug delivery capacity between the most and least effective devices. Most VHCs had a notable variation of performance between individual devices from different lots within the same brand.

CONCLUSIONS

There was an extreme variation in the salbutamol delivery performance among different types of VHCs for both normal and obstructive pediatric breathing patterns with and without masks. This magnitude of performance variability can have significant and unpredictable clinical implications.

Duration of Hospitalization in Association with Type of Inhalation Therapy Used in the Management of Children with Nonsevere, Acute Bronchiolitis

BACKGROUND

Acute bronchiolitis is one of the main respiratory emergencies in young children. Although supportive therapy is recommended, substantial inconsistency in the clinical usage of inhaled treatments has been reported. In the present study, we evaluated the association between different types of nebulized therapies in clinical practice and the length of stay (LOS) of young children hospitalized with nonsevere bronchiolitis.

METHODS

Medical records of 195 patients with bronchiolitis, without evidence of pneumonia or congenital/chronic respiratory conditions, were stratified with respect to the type of inhalation therapy received: nebulized albuterol (Group 1, n = 53), nebulized albuterol with 3% saline (Group 2, n = 38), nebulized 3% saline alone (Group 3, n = 33), or no inhaled treatment (Group 4, n = 71). Duration of hospital stay was reported with respect to the type of inhalation therapy received after controlling for variability in patient age (months), oxygen saturation, respiratory score, and use of other treatments (antibiotics, oxygen supplementation, and/or corticosteroids). LOS is presented in terms of mean and 95% confidence interval (95% CI).

RESULTS

The groups were similar except for differences in the mean level of oxygen saturation, respiratory score, and corticosteroid use. Children in Group 4 had the lowest mean respiratory score due to a lesser prevalence of wheezing and/or retractions than in other groups. The LOS for children in Groups 1 and 4 was shorter (43.2 hours, 95% CI 34.9-51.3, and 44.1 hours, 95% CI 37.3-51.0, respectively) than in Groups 2 and 3 (72 hours, 95% CI 62.1-81.6, and 65.1 hours, 95% CI 54.7-75.6, respectively) (p < 0.02). The mean LOS in each group did not change significantly after adjustment for covariants.

CONCLUSION

Prolonged hospitalization of children younger than 2 years with acute, nonsevere bronchiolitis is associated with administration of nebulized 3% saline, independent of age, clinical presentation of disease, or inclusion of other treatments in their management.

Pharmacokinetic properties and bioequivalence of orally inhaled salbutamol in healthy Chinese volunteers

CONTEXT

Salbutamol is a short-acting β2-adrenergic receptor agonist that has been used for many years for relief of bronchospasm. However, studies on the pharmacokinetic profile of orally inhaled salbutamol doses used in clinical practice have not yet been reported in Chinese subjects.

OBJECTIVE

The aim of this study was to compare the pharmacokinetics and evaluate the bioequivalence of two orally inhaled salbutamol formulations.

MATERIALS AND METHODS

A single-dose randomized fasting two-period, two-treatment and two-sequence crossover open-label bioequivalence study was conducted in 24 healthy Chinese adult male volunteers, with a 1-week washout period between treatments. Plasma concentrations of salbutamol were determined using liquid chromatography coupled to tandem mass spectrometry. Pharmacokinetic parameters, including AUC0-0.33 h, AUC0-24 h and Cmax were calculated and the 90% confidence intervals of the ratio (test/reference) pharmacokinetic parameters were obtained by analysis of variance on logarithmically transformed data.

RESULTS

The mean (SD) pharmacokinetic parameters of the reference drug were AUC0-0.33 h, 227.2 (89.9) pg·h/ml; AUC0-24 h, 2551.9 (1008.0) pg·h/ml; Cmax, 801.3 (307.3) pg/ml and t1/2, 5.14(1.36) h. Those of the test drug were AUC0-0.33 h, 244.0 (104.4) pg·h/ml; AUC0-24 h, 2664.4 (1081.8) pg·h/ml; Cmax, 873.7 (374.4) pg/ml, t1/2, 5.29 (1.23) h. The median value for Tmax was 0.25 h for both formulations. The 90% confidence intervals for the AUC0-0.33 h, AUC0-24 h and Cmax were in the range of 0.892-1.208, 0.876-1.195 and 0.911-1.203, respectively.

CONCLUSION

This single-dose study found that the test and reference products met the regulatory criteria for bioequivalence of China in healthy Chinese volunteers.

Inhalation treatment of lung cancer: the influence of composition, size and shape of nanocarriers on their lung accumulation and retention

Objective

Various nanoparticles have been designed and tested in order to select optimal carriers for the inhalation delivery of anticancer drugs to the lungs.

Methods

The following nanocarriers were studied: micelles, liposomes, mesoporous silica nanoparticles (MSNs), poly propyleneimine (PPI) dendrimer-siRNA complexes nanoparticles, quantum dots (QDs), and poly (ethylene glycol) polymers. All particles were characterized using the following methods: dynamic light scattering, zeta potential, atomic force microscopy, in vitro cyto- and genotoxicity. In vivo organ distribution of all nanoparticles, retention in the lungs, and anticancer effects of liposomes loaded with doxorubicin were examined in nude mice after the pulmonary or intravenous delivery.

Results

Significant differences in lung uptake were found after the inhalation delivery of lipid-based and non-lipid-based nanoparticles. The accumulation of liposomes and micelles in lungs remained relatively high even 24 h after inhalation when compared with MSNs, QDs, and PPI dendrimers. There were notable differences between nanoparticle accumulation in the lungs and other organs 1 and 3 h after inhalation or intravenous administrations, but 24 h after intravenous injection all nanoparticles were mainly accumulated in the liver, kidneys, and spleen. Inhalation delivery of doxorubicin by liposomes significantly enhanced its anticancer effect and prevented severe adverse side effects of the treatment in mice bearing the orthotopic model of lung cancer.

Conclusion

The results of the study demonstrate that lipid-based nanocarriers had considerably higher accumulation and longer retention time in the lungs when compared with non-lipid-based carriers after the inhalation delivery. These particles are most suitable for effective inhalation treatment of lung cancer.

Efficacy of inhaled ciprofloxacin in the management of non-cystic fibrosis bronchiectasis

Non-cystic fibrosis bronchiectasis (NCFBE), a historically under-recognized chronic respiratory condition, is a significant diagnosis currently experiencing a resurgence of interest in its clinical management. Ciprofloxacin is part of the current armamentarium used in the treatment of the recurrent respiratory tract infections seen in NCFBE. Inhaled ciprofloxacin, a novel method of drug delivery for the fluoroquinolone class, is being actively investigated. The inhaled formulation is designed to enhance drug delivery to the site of infection in the lung while minimizing the risk of systemic toxicity. This review summarizes the pharmacology and pharmacokinetics of ciprofloxacin and the rationale for the development of an inhaled formulation for NCFBE. Preclinical and clinical data regarding current development of inhaled ciprofloxacin formulations is also evaluated. Lastly, the anticipated role of inhaled ciprofloxacin in the management of NCFBE is discussed, including future considerations and potential limitations of therapy.

Clinical perspectives with long-term pulsed inhaled nitric oxide for the treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic, progressive disease of the pulmonary vasculature with a high morbidity and mortality. Its pathobiology involves at least three interacting pathways – prostacyclin (PGI₂), endothelin, and nitric oxide (NO). Current treatments target these three pathways utilizing PGI₂ and its analogs, endothelin receptor antagonists, and phosphodiesterase type-5 (PDE-5) inhibitors. Inhaled nitric oxide (iNO) is approved for the treatment of hypoxic respiratory failure associated with pulmonary hypertension in term/near-term neonates. As a selective pulmonary vasodilator, iNO can acutely decrease pulmonary artery pressure and pulmonary vascular resistance without affecting cardiac index or systemic vascular resistance. In addition to delivery via the endotracheal tube, iNO can also be administered as continuous inhalation via a facemask or a pulsed nasal delivery. Consistent with a deficiency in endogenously produced NO, long-term pulsed iNO dosing appears to favorably affect hemodynamics in PAH patients, observations that appear to correlate with benefit in uncontrolled settings. Clinical studies and case reports involving patients receiving long-term continuous pulsed iNO have shown minimal risk in terms of adverse events, changes in methemoglobin levels, and detectable exhaled or ambient NO or NO₂. Advances in gas delivery technology and strategies to optimize iNO dosing may enable broad-scale application to long-term treatment of chronic diseases such as PAH.