Use of gamma scintigraphy to evaluate the performance of new inhalers

Innovating on Inhaled Bioequivalence: A Critical Analysis of the Current Limitations, Potential Solutions and Stakeholders of the Process

Orally inhaled drug products (OIDPs) are an important group of medicines traditionally used to treat pulmonary diseases. Over the past decade, this trend has broadened, increasing their use in other conditions such as diabetes, expanding the interest in this administration route. Thus, the bioequivalence of OIDPs is more important than ever, aiming to increase access to affordable, safe and effective medicines, which translates into better public health policies. However, regulatory agencies leading the bioequivalence process are still deciding the best approach for ensuring a proposed inhalable product is bioequivalent. This lack of agreement translates into less cost-effective strategies to determine bioequivalence, discouraging innovation in this field. The Next-Generation Impactor (NGI) is an example of the slow pace at which the inhalation field evolves. The NGI was officially implemented in 2003, being the last equipment innovation for OIDP characterization. Even though it was a breakthrough in the field, it did not solve other deficiencies of the BE process such as dissolution rate analysis on physiologically relevant conditions, being the last attempt of transferring technology into the field. This review aims to reveal the steps required for innovation in the regulations defining the bioequivalence of OIDPs, elucidating the pitfalls of implementing new technologies in the current standards. To do so, we collected the opinion of experts from the literature to explain these trends, showing, for the first time, the stakeholders of the OIDP market. This review analyzes the stakeholders involved in the development, improvement and implementation of methodologies that can help assess bioequivalence between OIDPs. Additionally, it presents a list of methods potentially useful to overcome some of the current limitations of the bioequivalence standard methodologies. Finally, we review one of the most revolutionary approaches, the inhaled Biopharmaceutical Classification System (IBCs), which can help establish priorities and order in both the innovation process and in regulations for OIDPs.

Numerical and Experimental Investigation on Key Parameters of the Respimat® Spray Inhaler

Respimat®Soft MistTM is a newly developed spray inhaler. Different from traditional nebulizers, metered-dose inhalers, and dry powder inhalers, this new type of inhaler can produce aerosols with long duration, relatively slow speed, and a high content of fine particles. Investigating the effect of the key geometric parameters of the device on the atomization is of great significance for generic product development and inhaler optimization. In this paper, a laser high-speed camera experimental platform is built, and important parameters such as the geometric pattern and particle size distribution of the Respimat®Soft MistTM are measured. Computational fluid dynamics (CFD) and the volume of fluid method coupled with the Shear Stress Transport (SST) k-ω turbulence model are applied to simulate the key geometric parameters of the device. The effects of geometric parameters on the spray velocity distribution and geometric pattern are obtained. The angle of flow collision, the sphere size of the central divider and the length and width of the flow channel show significant impacts on the spray atomization.

Small Airway Absorption and Microdosimetry of Inhaled Corticosteroid Particles after Deposition

PURPOSE

To predict the cellular-level epithelial absorbed dose from deposited inhaled corticosteroid (ICS) particles in a model of an expanding and contracting small airway segment for different particle forms.

METHODS

A computational fluid dynamics (CFD)-based model of drug dissolution, absorption and clearance occurring in the surface liquid of a representative small airway generation (G13) was developed and used to evaluate epithelial dose for the same deposited drug mass of conventional microparticles, nanoaggregates and a true nanoaerosol. The ICS medications considered were budesonide (BD) and fluticasone propionate (FP). Within G13, total epithelial absorption efficiency (AE) and dose uniformity (microdosimetry) were evaluated.

RESULTS

Conventional microparticles resulted in very poor AE of FP (0.37%) and highly nonuniform epithelial absorption, such that <5% of cells received drug. Nanoaggregates improved AE of FP by a factor of 57-fold and improved dose delivery to reach approximately 40% of epithelial cells. True nanoaerosol resulted in near 100% AE for both drugs and more uniform drug delivery to all cells.

CONCLUSIONS

Current ICS therapies are absorbed by respiratory epithelial cells in a highly nonuniform manner that may partially explain poor clinical performance in the small airways. Both nanoaggregates and nanoaerosols can significantly improve ICS absorption efficiency and uniformity.

Inhaler devices for patients with COPD

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

Long-acting muscarinic receptor antagonists for the treatment of respiratory disease

The use of muscarinic receptor antagonists in the treatment of chronic obstructive pulmonary disease (COPD) is well established. More recently, the potential for long-acting muscarinic receptor antagonists (LAMAs) in the treatment of asthma has also been investigated. While LAMAs offer advantages over short-acting muscarinic receptor antagonists, in terms of a reduced dosing frequency, there remains a need for therapies that improve symptom control throughout both the day and night, provide better management of exacerbations and deliver improved health-related quality of life. Furthermore, the potential for unwanted anticholinergic side effects, particularly cardiovascular effects, remains a concern for this class of compounds. Novel LAMAs in clinical development for the treatment of respiratory disease include: aclidinium bromide, NVA237 (glycopyrronium bromide), GP-MDI, EP-101, CHF-5259, umeclidinium bromide, CHF-5407, TD-4208, AZD8683 and V-0162. These compounds offer potential advantages in terms of onset of action, symptom control and safety. In addition, a number of LAMAs are also being developed as combination treatments with long-acting β2-agonists (LABAs) or inhaled glucocorticosteroids, potentially important treatment options for patients who require combination therapy to achieve an optimal therapeutic response as their disease progresses. More recently, compounds such as GSK961081 and THRX-198321 have been identified that combine LAMA and LABA activity in the same molecule, and have the potential to offer the benefits of combination therapy in a single compound. Here, we review novel LAMAs and dual action compounds in clinical development, with a particular focus on how they may address the current unmet clinical needs in the treatment of respiratory disease, particularly COPD.

Lack of paradoxical bronchoconstriction after administration of tiotropium via Respimat® Soft Mist™ Inhaler in COPD

Bronchoconstriction has been reported in asthma and chronic obstructive pulmonary disease (COPD) patients after administration of some aqueous inhalation solutions. We investigated the incidence of this event during long-term clinical trials of tiotropium delivered via Respimat^® Soft Mist™ Inhaler (SMI). We retrospectively analyzed pooled data from two identical Phase III clinical trials, in which 1990 patients with COPD received 48 weeks’ treatment with once-daily tiotropium (5 or 10 μg) or placebo inhaled via Respimat^® SMI. We recorded the incidence of bronchospasm and of a range of respiratory events that could suggest bronchoconstriction during the first 30 minutes after inhalation of study treatment on each of the eight test days. No patients reported bronchospasm. Six patients (0.3%) reported a combination of at least two events suggestive of bronchoconstriction, and 21 (1.1%) reported either rescue medication use or a respiratory adverse event. Asymptomatic falls in forced expiratory volume in one second (FEV₁) of ≥15% were recorded on all test days, with no change in incidence over time, and affected 8.2% of those in the tiotropium groups and 14.5% of those on placebo. In COPD patients receiving long-term treatment with tiotropium 5 or 10 μg via Respimat^® SMI, no bronchospasm was recorded, and the number of events possibly indicative of paradoxical bronchoconstriction was very low.

Tiotropium 5microg via Respimat and 18microg via HandiHaler; efficacy and safety in Japanese COPD patients

BACKGROUND AND OBJECTIVES

To compare the efficacy and safety of tiotropium inhaled via Respimat Soft Mist Inhaler, a multidose propellant-free inhaler and HandiHaler, a single-dose dry powder inhaler, in a phase 2 study of Japanese COPD patients.

METHODS

Patients with FEV(1)<or=70% predicted, FEV(1)/FVC<or=70% and a smoking history of >10 pack-years received tiotropium once daily via Respimat (5microg) and HandiHaler (18microg) for 4 weeks each in a randomised, double-blind, double-dummy, two-way crossover study. Lung function, adverse events, pharmacokinetics and safety were assessed.

RESULTS

Of 184 patients screened, 134 were evaluable. The trough FEV(1) response on Day 29 showed Respimat to be non-inferior to HandiHaler (mean treatment difference, 0.008L; 95% CI, -0.009 to +0.024L; p<0.001). Peak and average FEV(1) and FVC responses on Day 1 and Day 29 were very similar for the two treatments. Tiotropium plasma levels and excretion kinetics showed a similar profile of systemic exposure for the two formulations of tiotropium. Adverse events were reported by similar numbers of patients on each treatment, i.e. 27.9 and 30.6% in the Respimat and HandiHaler groups, respectively.

CONCLUSIONS

In Japanese patients with COPD, tiotropium Respimat 5microg and tiotropium HandiHaler 18microg showed a similar profile of efficacy, safety and pharmacokinetics.

Patient preferences for inhaler devices in chronic obstructive pulmonary disease: experience with Respimat Soft Mist inhaler

Current guidelines for the management of chronic obstructive pulmonary disease (COPD) recommend the regular use of inhaled bronchodilator therapy in order to relieve symptoms and prevent exacerbations. A variety of inhaler devices are currently available to COPD patients, and the choice of device is an important consideration because it can influence patients' adherence to treatment, and thus potentially affect the long-term outcome. The Respimat((R)) Soft Mist Inhaler (SMI) generates a slow-moving aerosol with a high fine particle fraction, resulting in deposition of a higher proportion of the dose in the lungs than pressurized metered-dose inhalers (pMDIs) or some dry powder inhalers (DPIs). We review clinical studies of inhaler satisfaction and preference comparing Respimat((R)) SMI against other inhalers in COPD patients. Using objective and validated patient satisfaction instruments, Respimat((R)) SMI was consistently shown to be well accepted by COPD patients, largely due to its inhalation and handling characteristics. In comparative studies with pMDIs, the patient total satisfaction score with Respimat((R)) SMI was statistically and clinically significantly higher than with the pMDI. In comparative studies with DPIs, the total satisfaction score was statistically significantly higher than for the Turbuhaler((R)) DPI, but only the performance domain of satisfaction was clinically significantly higher for Respimat((R)) SMI. Whether the observed higher levels of patient satisfaction reported with Respimat((R)) SMI might be expected to result in improved adherence to therapy and thus provide benefits consistent with those recently shown to be associated with sustained bronchodilator treatment in patients with COPD remains to be proven.

An in vitro study to assess facial and ocular deposition from Respimat Soft Mist inhaler

Respimat Soft Mist() inhaler (SMI) is a novel multidose propellant-free inhaler device for delivery of inhaled drugs to patients with asthma and chronic obstructive pulmonary disease. In vitro studies have been undertaken to assess facial and ocular deposition from Respimat SMI in several potential misuse situations. A placebo aqueous drug formulation in Respimat SMI was radiolabeled by addition of (99m)Tc. Deposition was quantified by gamma camera on a removable facemask that was fitted over the head of a resuscitation mannequin. The eyes were simulated by adhesive plaster patches. When Respimat SMI was fired in three preselected positions away from the head, total face deposition (% ex-valve dose) averaged 7.3%, 7.8%, and 9.1%, and eye deposition averaged 0.6%, 0.1%, and 0.3%. When the inhaler was fired into a simulated exhalation, upper face deposition (mean 3.8%) and eye deposition (mean 0.1%) were also small. It is concluded that low deposition on the face, and especially in the eyes, is to be expected when Respimat SMI is fired accidentally outside the body, or is fired at the same time as the patient exhales. When Respimat SMI is misused in the ways described in this study, there is likely to be little potential for unwanted side effects resulting from ocular deposition.

Deposition of corticosteroid aerosol in the human lung by Respimat Soft Mist inhaler compared to deposition by metered dose inhaler or by Turbuhaler dry powder inhaler

Fourteen mild-to-moderate asthmatic patients completed a randomized four-way crossover scintigraphic study to determine the lung deposition of 200 microg budesonide inhaled from a Respimat Soft Mist Inhaler (Respimat SMI), 200 microg budesonide inhaled from a Turbuhaler dry powder inhaler (Turbuhaler DPI, used with fast and slow peak inhaled flow rates), and 250 microg beclomethasone dipropionate inhaled from a pressurized metered dose inhaler (Becloforte pMDI). Mean (range) whole lung deposition of drug from the Respimat SMI (51.6 [46-57]% of the metered dose) was significantly (p < 0.001) greater than that from the Turbuhaler DPI used with both fast and slow inhaled flow rates (28.5 [24-33]% and 17.8 [14-22]%, respectively) or from the Becloforte pMDI (8.9 [6-12]%). The deposition pattern within the lungs was more peripheral for Respimat SMI than for Turbuhaler DPI. The results of this study showed that Respimat SMI deposited corticosteroid more efficiently in the lungs than either of two widely used inhaler devices, Turbuhaler DPI or Becloforte pMDI.

A review of the development of Respimat Soft Mist Inhaler

Respimat Soft Mist Inhaler (SMI) is a new generation inhaler from Boehringer Ingelheim developed for use with respiratory drugs. The device functions by forcing a metered dose of drug solution through a unique and precisely engineered nozzle (the uniblock), producing two fine jets of liquid that converge at a pre-set angle. The collision of these two jets generates the soft mist. The soft mist contains a high fine particle fraction of approximately 65 to 80%. This is higher than aerosol clouds from conventional portable inhaler devices, such as pressurised metered dose inhalers (pMDIs) and dry powder inhalers (DPIs). In addition, the relatively long generation time of the aerosol cloud (approximately 1.5s) facilitates co-ordination of inhalation and actuation--a major problem with pMDIs. These features, together with the slow velocity of the soft mist, result in larger amounts of the drug reaching the lungs and less being deposited in the oropharynx compared with either pMDIs or DPIs. Generation of the soft mist from Respimat SMI is purely mechanical, so propellants are not necessary. The innovative design of Respimat SMI, using water-based drug formulations, ensures patients receive consistent and reliable doses of the drug with each actuation. The device was initially tested in scintigraphic lung deposition studies and produced encouraging results when compared with the chlorofluorocarbon-based pMDI (CFC-MDI). Subsequent clinical studies have confirmed that Respimat SMI is effective and safe in delivering bronchodilators to patients with asthma or chronic obstructive pulmonary disease.

A novel propellant-free inhalation drug delivery system for cardiovascular drug safety evaluation in conscious dogs

INTRODUCTION

Estimation of possible cardiovascular side effects belongs to the safety assessment of every drug candidate. This paper describes a new strategy for treating conscious labrador dogs with drugs by inhalation using a specially designed mask and a novel inhaler device.

METHODS

Labrador dogs (male or female) were used that had transducers implanted for the measurement of left ventricular and descending aortic blood pressures and an ECG for use together with a telemetry system. Administration by inhalation was achieved using a novel delivery device. The Respimat device is a propellant-free inhaler to deliver aerosols from solutions. The new system was evaluated using Formoterol with four dogs using a 4 x 4 Latin square design. Three doses of Formoterol (0.6, 1.2, and 2.4 microg/kg, dissolved in 60% ethanol) were administered by inhalation together with a vehicle (60% ethanol) treatment by applying three inhalations, each consisting of 10 microl solution.

RESULTS

Formoterol increased HR, QRS-interval, QT-interval, and LVPdP/dtmax and dose-dependently decreased systolic and diastolic BP. This effect lasted up to 14 h.

DISCUSSION

Drug administration by inhalation in the conscious labrador dog using the Respimat is a useful new model for safety pharmacology studies of new drug candidates that are intended to be given by inhalation in the clinic.

Multimodal particle size distributions emitted from HFA-134a solution pressurized metered-dose inhalers

The purpose of this research was to investigate the measurement and in vitro delivery implications of multimodal distributions, occurring near or in the respirable range, emitted from pressurized metered-dose inhalers (pMDIs). Particle size distributions of solution pMDIs containing hydrofluoroalkane-134a (HFA-134a) and ethanol were evaluated using 2 complementary particle-sizing methods: laser diffraction (LD) and cascade impaction (CI). Solution pMDIs were formulated from mixtures of HFA-134a (50%-97.5% wt/wt) and ethanol. A range of propellant concentrations was selected for a range of vapor pressures. The fluorescent probe, Rhodamine B, was included for chemical analysis. The complementary nature of LD and CI allowed identification of 2 dominant particle size modes at 1 and 10 micro m or greater. Increasing propellant concentrations resulted in increases in the proportion of the size distributions at the 1- micro m mode and also reduced the particle size of the larger droplet population. Despite significant spatial differences and time scales of measurement between the particle-sizing techniques, the fine particle fractions obtained from LD and CI were practically identical. This was consistent with LD experiments, which showed that particle sizes did not decrease with increasing measurement distance, and may be explained by the absence of significant evaporation/disintegration of larger droplets. The fine particle fractions (FPFs) emitted from HFA-134a/ethanol solution pMDI can be predicted on the basis of formulation parameters and is independent of measurement technique. These results highlight the importance of presenting particle size distribution data from complementary particle size techniques.

Aerosolized protein delivery in asthma: gamma camera analysis of regional deposition and perfusion

Bioavailability of an aerosolized anti-inflammatory protein, soluble interleukin-4 receptor (IL-4R), was measured in patients with asthma using two different aerosol delivery systems, a prototype aerosol delivery system (AERx tethered model, Aradigm, Hayward, CA) and PARI LC STAR nebulizer (Pari, Richmond, VA). Regional distribution of the drug in the respiratory tract obtained by planar imaging using gamma camera scintigraphy was utilized to explain the differences in bioavailability. The drug, an experimental protein being developed for asthma, was mixed with radiolabel 99mTechnetium diethylene triaminepentaacetic acid (99mTc-DTPA). Aerosols were characterized in vitro using cascade impaction (mass median aerodynamic diameter [MMAD] and geometric standard deviation [GSD]); the AERx MMAD 2.0 microm (GSD 1.35), the PARI 3.5 microm (GSD 2.5). Four patients with asthma requiring maintenance aerosolized steroids were studied. First, regional volume was determined utilizing equilibrium 133Xe scanning. Then, after a brief period of instruction, patients inhaled four breaths of protein using AERx (0.45 mg in total) followed 1 week later by inhalation via PARI (3.0 mg nebulized until dry). Each deposition image was followed by a measurement of regional perfusion using injected 99mTc albumin macroaggregates. Deposition of 99mTc-DTPA in the subjects was determined by mass balance. Regional analysis was performed using computerized regions of interest. The regional distribution of deposited drug was normalized for regional volume and perfusion. Following each single inhalation, serial blood samples were drawn over a 7-day period to determine area under the curve (AUC) of protein concentration in the blood. Median AUC(AERx)/AUC(PARI) was 7.66/1, based on the amount of drug placed in each device, indicating that AERx was 7.66 times more efficient than PARI. When normalized for total lung deposition (AUC per mg deposited) the ratio decreased to 2.44, indicating that efficiencies of the drug delivery system and deposition were major factors. When normalized for sC/P and (pU/L)xe ratios (central to peripheral and upper to lower ratios are parameters of regional distribution of deposited particles and regional per- fusion ['p']), AUC(AER)x/AUC(PARI) further decreased to 1.35, demonstrating that peripheral sites of deposition with the AERx affected the final blood concentration of the drug. We conclude that inhaled bioavailability of aerosolized protein, as expressed by AUC, is a quantifiable function of lung dose and regional deposition as defined by planar scintigraphy.