Pharmaceutical transition to non-CFC pressurized metered dose inhalers

Development of an Ethanol-Free Salbutamol Sulfate Metered-Dose Inhaler: Application of Molecular Dynamic Simulation-based Prediction of Intermolecular Interaction

INTRODUCTION

More than fifty years after the commercialization of the Ventolin metered-dose inhaler (MDI), its constituent active ingredient, salbutamol sulfate (SS) remains the most prescribed short-acting beta agonist for the first-line treatment of acute asthma attacks and the metered-dose inhaler remains its primary dosage form. The first generation of Ventolin MDI was developed at a time when environmental and regulatory concerns were less stringent than today. The MDI industry is now on the verge of a second major reformulation effort in response to environmental concerns. This paper serves to illustrate how modern computational modeling of molecular interactions can aid the reformulation process. By way of a case study, computational modeling was performed to compare poly(ethylene glycol) 400 (PEG400) and, separately, isopropyl myristate (IPM) as substitutes for the ethanol used in some generic salbutamol sulfate suspension-based hydrofluoroalkane MDIs.

METHODS

PEG400 and isopropyl myristate (IPM) were investigated as potential alternative cosolvents to ethanol in HFA134a-based SS suspension MDI formulations. Density functional theory (DFT) molecular dynamics simulations were used to evaluate the compatibility of the candidate cosolvents with the formulation's components. Corresponding physical formulations were filled into polyethylene terephthalate (PET) and, separately, aluminium canisters. In-vitro pharmaceutical product performance and macroscopic visual appearance were assessed and compared to the results of the simulation studies.

RESULTS

The simulation studies indicated that PEG400 would be a good candidate as a replacement for ethanol whereas IPM would not. The in-vitro and visual assessments support the predicted outcome of the simulation studies.

CONCLUSION

This work suggests that molecular dynamics simulations may provide a useful tool to aid the selection of compatible excipients when reformulating MDI suspension-based products, thereby reducing the time and cost associated with manufacturing and testing of physical samples.

The Potential Use of Cyclosporine Ultrafine Solution Pressurised Metered- Dose Inhaler in the Treatment of COVID-19 Patients

INTRODUCTION

Serious COVID-19 respiratory problems start when the virus reaches the alveolar level, where type II cells get infected and die. Therefore, virus inhibition at the alveolar level would help preventing these respiratory complications.

METHOD

A literature search was conducted to collect physicochemical properties of small molecule compounds that could be used for the COVID-19 treatment. Compounds with low melting points were selected along with those soluble in ethanol, hydrogen-bond donors, and acceptors.

RESULTS

There are severe acute respiratory syndrome coronavirus inhibitors with physicochemical properties suitable for the formulation as an ultrafine pressurised metered-dose inhaler (pMDI). Mycophenolic acid, Debio 025, and cyclosporine A are prime candidates among these compounds. Cyclosporine A (hereafter cyclosporine) is a potent SARS-CoV-2 inhibitor, and it has been used for the treatment of COVID-19 patients, demonstrating an improved survival rate. Also, inhalation therapy of nebulised cyclosporine was tolerated, which was used for patients with lung transplants. Finally, cyclosporine has been formulated as a solution ultrafine pMDI. Although vaccine therapy has started in most countries, inhalation therapies with non-immunological activities could minimise the spread of the disease and be used in vaccine-hesitant individuals.

CONCLUSION

Ultrafine pMDI formulation of cyclosporine or Debio 025 should be investigated for the inhalation therapy of COVID-19.

Water Uptake by Evaporating pMDI Aerosol Prior to Inhalation Affects Both Regional and Total Deposition in the Respiratory System

As pulmonary drug deposition is a function of aerosol particle size distribution, it is critical that the dynamics of particle formation and maturation in pMDI sprays in the interim between generation and inhalation are fully understood. This paper presents an approach to measure the evaporative and condensational fluxes of volatile components and water from and to solution pMDI droplets following generation using a novel technique referred to as the Single Particle Electrodynamic Lung (SPEL). In doing so, evaporating aerosol droplets are shown capable of acting as condensation nuclei for water. Indeed, we show that the rapid vaporisation of volatile components from a volatile droplet is directly correlated to the volume of water taken up by condensation. Furthermore, a significant volume of water is shown to condense on droplets of a model pMDI formulation (hydrofluoroalkane (HFA), ethanol and glycerol) during evaporative droplet ageing, displaying a dramatic shift from a core composition of a volatile species to that of predominantly water (non-volatile glycerol remained in this case). This yields a droplet with a water activity of 0.98 at the instance of inhalation. The implications of these results on regional and total pulmonary drug deposition are explored using the International Commission of Radiological Protection (ICRP) deposition model, with an integrated semi-analytical treatment of hygroscopic growth. Through this, droplets with water activity of 0.98 upon inhalation are shown to produce markedly different dose deposition profiles to those with lower water activities at the point of inspiration.

Effects of Inhaled Corticosteroids and Particle Size on Risk of Obstructive Sleep Apnea: A Large Retrospective Cohort Study

Background: Inhaled corticosteroids (ICS) produce local effects on upper airway dilators that could increase the risk of developing obstructive sleep apnea (OSA). Given that the particle size of ICS changes their distribution, the particle size of ICS may impact the risk of developing OSA. Objectives: In this large retrospective study, we explore the relationship of ICS use and OSA in patients with asthma. In addition, we seek to determine if this relationship is affected by the particle size of ICS. Methods: Using electronic health records, we established a cohort of 29,816 asthmatics aged 12 and older with a diagnosis of asthma documented by ICD-9 or ICD-10 codes between January 2011 and August 2016. We performed analyses of variance and multivariate logistic regression analysis to determine the effects ICS on the diagnosis of OSA with sub-analysis by particle size of ICS. Results: Uncontrolled asthmatics showed increased odds of receiving a diagnosis of OSA whether when looking at ACT scores (adjusted odds ratio (aOR) 1.60, 95% CI 1.32–1.94) or PFT results (aOR 1.45, 95% CI 1.19–1.77). Users of ICS also had increased odds of OSA independent of asthma control (aOR 1.58, 95% CI 1.47–1.70). Notably, users of extra-fine particle ICS did not have significantly increased odds of having OSA compared to non-users of ICS (aOR 1.11, 95% CI 0.78–1.58). Conclusions: Use of ICS appears to be an independent risk factor for OSA. Notably, extra-fine particle size ICS do not appear to be associated with an increased risk of OSA.

Cascade Impactor Performance of Commercial pMDI Formulations Using Modified Induction Ports

The induction port (IP) for aerosol analysis with the Next Generation Pharmaceutical Impactor as monographed in the United States and European pharmacopoeia (USPIP) lacks physiological relevance, which, amongst other reasons, has been identified as critical for the predictability of in vitro aerosol data to lung deposition observed in vivo. In this publication, we report the impact of replacing the USPIP with two modified induction ports, which were designed based around geometries derived from a computer tomographic scan of a human trachea and the distal section of the USPIP. Test formulations were selected on the basis of availability of in vivo lung deposition data so that results obtained in vitro could be evaluated for their predictability. All formulations assessed showed increased deposition in the modified induction ports, and different mechanisms of particle deposition have been identified. In vitro predictions of the lung deposition were found to correlate well with the in vivo observations reported using the modified induction ports. Furthermore, the quality of the correlation was found superior to the one achieved with the USPIP with an average deviation of the predicted from observed values (n = 10) of 6 ± 4, 12 ± 6, and 16 ± 6% for the modified induction ports (mIP and mIPext) and the USPIP, respectively, when using a fine particle fraction (FPF) cutoff value of 5 μm. Using a FPF cutoff value of 3 μm yielded a more accurate in vitro-in vivo correlation with an average deviation of the predicted from observed values of 5 ± 4, 7 ± 5, and 8 ± 4% for the mIP, mIPext, and USPIP, respectively. For both FPF size cutoff values, the mIP yielded the most accurate in vitro-in vivo correlation.

Measurement of the Raman spectra and hygroscopicity of four pharmaceutical aerosols as they travel from pressurised metered dose inhalers (pMDI) to a model lung

Particle inhalation is an effective and rapid delivery method for a variety of pharmaceuticals, particularly bronchodilation drugs used for treating asthma and COPD. Conditions of relative humidity and temperature inside the lungs are generally very different from the outside ambient air, with the lung typically being warmer and more humid. Changes in humidity, from inhaler to lung, can cause hygroscopic phase transitions and particle growth. Increasing particle size and mass can negatively affect particle deposition within the lung leading to inefficient treatment, while deliquescence prior to impaction is liable to accelerate drug uptake. To better understand the hygroscopic properties of four pharmaceutical aerosol particles; pharmaceutical particles from four commercially available pressurised metered dose inhalers (pMDIs) were stably captured in an optical trap, and their composition was examined online via Raman spectroscopy. Micron-sized particles of salbutamol sulfate, salmeterol xinafoate, fluticasone propionate and ciclesonide were levitated and examined over a range of relative humidity values inside a chamber designed to mimic conditions within the respiratory tract. The effect of temperature upon hygroscopicity was also investigated for salbutamol sulfate particles. Salbutamol sulfate was found to have significant hygroscopicity, salmeterol xinafoate showed some hygroscopic interactions, whilst fluticasone propionate and ciclesonide revealed no observable hygroscopicity. Thermodynamic and structural modelling is used to explain the observed experimental results.

Cost-effectiveness of initiating extrafine- or standard size-particle inhaled corticosteroid for asthma in two health-care systems: a retrospective matched cohort study

BACKGROUND

Real-life studies are needed to determine the cost-effectiveness of asthma therapies in clinical practice.

AIM

To compare the cost-effectiveness of extrafine-particle inhaled corticosteroid (ICS) with standard size-particle ICS in the United Kingdom (UK) and United States (US).

METHODS

These retrospective matched cohort analyses used large electronic databases to study asthma-related outcomes for patients in the UK (12-60 years old; n=1730) and US (12-80 years; n=10,312) prescribed extrafine beclomethasone or fluticasone as their first ICS therapy for asthma. Patients were matched on demographic characteristics and asthma severity during 1 baseline year, and asthma control and asthma-related costs were compared during 1 outcome year.

RESULTS

In both the UK and US, adjusted odds of risk-domain asthma control were similar, whereas the odds of overall control (no hospitalisation or oral steroids for asthma, no antibiotics for lower respiratory infection, limited reliever use) were greater for extrafine ICS in both countries (UK odds ratio, 1.23; 95% confidence interval (CI), 1.01-1.50). Asthma-related annual costs, adjusted for baseline, were significantly lower for extrafine-particle ICS cohorts in both countries (UK difference, -£66 (95% CI,-93 to -37)). Cost-effectiveness analyses using the two measures of asthma control found 92 and 98% probabilities of extrafine-particle ICS being the preferred treatment strategy (less costly and more effective than standard size-particle ICS) in the UK, and 84 and 100% probabilities in the US.

CONCLUSIONS

Initiating ICS therapy for asthma as extrafine-particle ICS seems the dominant treatment option (less costly and more effective) compared with standard size-particle ICS in both the UK and the US.

Considerations for Designing In Vitro Bioequivalence (IVBE) Studies for Pressurized Metered Dose Inhalers (pMDIs) with Spacer or Valved Holding Chamber (S/VHC) Add-on Devices

BACKGROUND

The choice of analytical test methods and associated statistical considerations are considered for the laboratory testing of pressurized metered dose inhaler-spacer/valved holding chamber (pMDI-S/VHC) combinations for in vitro bioequivalence (IVBE).

METHODS

Four scenarios are presented for comparing TEST ("second entry" or "generic") versus REF ("innovator"): (1) innovator and second entry product pMDI alone without any S/VHC (baseline comparison); (2) innovator and second entry pMDI product with the same S/VHC; (3) innovator pMDI product with existing S/VHC and second entry product with a different S/VHC; and (4) introduction of a second, different S/VHC to be used with a given innovator pMDI product. The following aspects should be reviewed in the preparatory stage of designing experiments to establish IVBE: (a) the inclusion of delayed inhalation; (b) the utilization of age-appropriate flow rates; and (c) the use of anatomically appropriate face models for evaluation of devices with a facemask. Statistical considerations that fit in with such experimental methods include: selection of pMDI batches and S/VHC lots; choice of sample size and acceptance criteria; bracketing or worst case approaches; and balanced/paired designs. A stepwise approach for selection of impactor stage groupings is presented, and an approach to determine realistic acceptance criteria based on REF product characteristics is suggested.

RESULTS

An example of an efficient statistical design of experiment is provided for each scenario, together with alternate approaches for calculation of confidence intervals for the mean TEST/REF relationship. It is important to appreciate that the optimal design depends on balancing numerous considerations and will thus likely differ from case to case; hence, the designs presented here should be seen as illustrations rather than the only option available. More effective approaches may be found that suit a particular case at hand.

CONCLUSIONS

The information provided will assist in developing correlations in support of IVBE for these add-on devices.

The effect of nonideal cascade impactor stage collection efficiency curves on the interpretation of the size of inhaler-generated aerosols

Cascade impactors, operating on the principle of inertial size separation in (ideally) laminar flow, are used to determine aerodynamic particle size distributions (APSDs) of orally inhaled product (OIP) aerosols because aerodynamic diameter can be related to respiratory tract deposition. Each stage is assumed typically to be an ideal size fractionator. Thus, all particles larger than a certain size are considered collected and all finer particles are treated as penetrating to the next stage (a step function stage efficiency curve). In reality, the collection efficiency of a stage smoothly increases with particle size as an "S-shaped" curve, from approximately 0% to 100%. Consequently, in some cases substantial overlap occurs between neighboring stages. The potential for bias associated with the step-function assumption has been explored, taking full resolution and two-stage abbreviated forms of the Andersen eight-stage nonviable impactor (ACI) and the next-generation pharmaceutical impactor (NGI) as example apparatuses. The behavior of unimodal, log-normal APSDs typical of OIP-generated aerosols has been investigated, comparing known input values to calculated values of central tendency (mass median aerodynamic diameter) and spread (geometric standard deviation, GSD). These calculations show that the error introduced by the step change assumption is larger for the ACI than for the NGI. However, the error is sufficiently small to be inconsequential unless the APSD in nearly monodisperse (GSD ≤1.2), a condition that is unlikely to occur with realistic OIPs. Account may need to be taken of this source of bias only for the most accurate work with abbreviated ACI systems.

Treating the small airways

The final article in this series evaluates the approaches undertaken to treating the small-airway region of the lungs and the clinical implications of inhaled therapy targeting the periphery in patients with asthma and chronic obstructive pulmonary disease.

Undiagnosed submucous cleft palate interfering with inhalation therapy and a solution

Patients with velopharyngeal insufficiency who require inhalation therapy should be advised to hold their noses when inhaling medication to ensure that they receive the dosage prescribed.

Incentive device improves spacer technique but not clinical outcome in preschool children with asthma

AIM

To investigate the influence of an incentive device, the Funhaler, on spacer technique and symptom control in young children with asthma and recurrent wheeze.

METHODS

Randomised controlled trial where 132 2-6 year old asthmatic children received regular inhaled fluticasone through Aerochamber Plus, or Funhaler. The setting was a research clinic at Princess Margaret Hospital for Children, Perth, Australia. Subjects were followed up for a year. The main outcome measure was asthma symptoms. Proficiency in spacer technique was measured as salbutamol inhaled from spacer onto filter. Quality of life was measured every three months. Groups were compared in terms of spacer technique, symptoms and quality of life. The relationship between spacer technique and clinical outcome was examined.

RESULTS

There was no difference between Funhaler and Aerochamber groups in wheeze free days, cough free days, bronchodilator free days or quality of life (P = 0.90, 0.87, 0.74 and 0.11 respectively). Spacer technique was better in the Funhaler group (P = 0.05), particularly in subjects younger than 4 years of age (P = 0.002). Drug dose on filter (as the mean of five 100 mg doses) ranged from zero to 136 mg.

CONCLUSIONS

Use of Funhaler incentive device does not improve clinical outcome, but improves spacer technique in children younger than 4 years. Variability in drug delivery is large in young children using pressurised metered dose inhalers and spacers.

Hydrofluoroalkane preparations of fluticasone propionate

Fluticasone propionate is approved for the long-term maintenance therapy of persistent asthma of all severities, and its safety and efficacy has been well established in clinical trials and practice. With the need to phase out chlorofluorocarbons (CFCs) as propellants in pressurized metered-dose inhalers (pMDIs), hydrofluoroalkane (HFA) propellants have been introduced as a safer, environmentally friendly alternative. A HFA formulation of fluticasone propionate has been developed as a microgram-equivalent replacement for the traditional CFC pMDI. Clinical trials have demonstrated that the fluticasone propionate HFA pMDI is an acceptable clinical alternative for the CFC pMDI with similar safety and efficacy.

Salbutamol relative lung and systemic bioavailability of large and small spacers

Differences between the size and shape of spacers may affect the emitted dose and provide different effects when interchanged during routine use. Using a urinary pharmacokinetic method we have measured the relative lung and systemic bioavailability from urinary salbutamol excretion 30 min (USAL0.5) and 24 h (USAL24), respectively, after the inhalation of two 100-μg doses from a Ventolin Evohaler when used alone (MDI) and when attached to the Volumatic (VOL) or the Aerochamber Plus (AERO) spacers. The in-vitro properties of the emitted dose were determined. The mean (s.d.) USAL0.5 values following MDI, VOL and AERO (n = 13 volunteers) were 5.7 (1.9), 16.4 (8.2) and 14.8 (7.4) μg, respectively. VOL and AERO were significantly greater (P < 0.001 and < 0.01, respectively) than MDI. Comparison of VOL and AERO was similar with a mean ratio (90% confidence interval) of 108.2 (84.5, 138.6)%. USAL24 values between the three inhalation methods were similar. The values for the mean (s.d.) fine particle dose of two 100-μg doses emitted from MDI, VOL and AERO were 83.0 (6.8), 83.6 (4.6) and 73.6 (2.9) μg and the mass median aerodynamic diameters were 2.7 (0.03), 2.8 (0.07) and 2.9 (0.10) μm, respectively. The results showed that during routine use the Volumatic and the Aerochamber Plus spacers should provide similar lung and systemic delivery when attached to a Ventolin Evohaler.

Levalbuterol versus albuterol

Albuterol has been used for more than 40 years to treat acute asthma exacerbations as a racemic mixture of isomers: the active form, (R)-albuterol, or levalbuterol, and (S)-albuterol, classically considered inert. The single-isomer formulation, levalbuterol, has been synthesized recently and used therapeutically when the racemate is deemed less desirable. Basic investigations indicate that racemic albuterol and levalbuterol can produce effects that favor asthma remediation, including corticosteroid amplification and reduction of inflammatory mediators; in contrast, (S)-albuterol produces opposite effects. With inhalation of racemic albuterol, circulating (S)-albuterol persists 12 times longer than levalbuterol, suggesting potential for paradoxical effects observed clinically. Although mainly consistent with basic findings, clinical studies suggest no overwhelming superiority of levalbuterol over racemic albuterol; however, levalbuterol's effects may be greatest in moderate to severe asthma patients, especially with racemic albuterol overuse. Recent adoption of the hydrofluoroalkane formulation has narrowed the cost gap between levalbuterol and racemic albuterol metered-dose inhalers, but it remains for the nebulized formulations. Thus, physician selection of these drugs has remained dependent on experience, pharmaceutical knowledge, and established prescribing habits combined with cost factors, formulary structures, and availability, such that racemic albuterol is still used significantly compared with levalbuterol to treat acute asthma exacerbations.

The abbreviated impactor measurement (AIM) concept: part 1--Influence of particle bounce and re-entrainment-evaluation with a "dry" pressurized metered dose inhaler (pMDI)-based formulation

The abbreviated impactor measurement concept is a potential improvement to the labor-intensive full-resolution cascade impactor methodology for inhaler aerosol aerodynamic particle size distribution (APSD) measurement by virtue of being simpler and therefore quicker to execute. At the same time, improved measurement precision should be possible by eliminating stages upon which little or no drug mass is collected. Although several designs of abbreviated impactor systems have been developed in recent years, experimental work is lacking to validate the technique with aerosols produced by currently available inhalers. In part 1 of this two-part article that focuses on aerosols produced by pressurized metered dose inhalers (pMDIs), the evaluation of two abbreviated impactor systems (Copley fast screening Andersen impactor and Trudell fast screening Andersen impactor), based on the full-resolution eight-stage Andersen nonviable cascade impactor (ACI) operating principle, is reported with a formulation producing dry particles. The purpose was to investigate the potential for non-ideal collection behavior associated with particle bounce in relation to internal losses to surfaces from which particles containing active pharmaceutical ingredient are not normally recovered. Both abbreviated impactors were found to be substantially equivalent to the full-resolution ACI in terms of extra-fine and fine particle and coarse mass fractions used as metrics to characterize the APSD of these pMDI-produced aerosols when sampled at 28.3 L/min, provided that precautions are taken to coat collection plates to minimize bounce and entrainment.

Investigations into the formulation of metered dose inhalers of salmeterol xinafoate and fluticasone propionate microcrystals

PURPOSE

To investigate the aerosolization and behaviour of microparticles of salmeterol xinafoate (SX) and fluticasone propionate (FP) suspended in hydrofluoroalkane (HFA) propellant.

METHODS

Microcrystals of SX and FP were produced from poly(ethylene glycol) by antisolvent crystallization. The suspension behaviour and aerosolization of the microcrystals when formulated as metered dose inhalers (MDIs) in HFA 134a propellant was compared with that of microparticles produced by micronization (mSX and mFP) using a glass twin stage impinger and by laser light diffraction using a pressurized cell.

RESULTS

FP microparticles underwent non-reversible aggregation in suspension as seen by a doubling in the volume median diameter compared to the raw material. The degree of aggregation of SX particles in suspension was found to decrease as the particle size of the original particles increased. However, because the SX aggregate size was lowest for the particles with the smallest initial size (mSX), the highest fine particle fraction (FPF) of SX was obtained from a suspension of mSX. The FPFs following aerosolization of FP suspensions were similar although the FPF was lowest for particles with the largest original size.

CONCLUSIONS

The size of the aggregates in the HFA suspensions was found to correlate directly with the FPFs determined by impaction.

Systemic exposure and urinary cortisol effects of fluticasone propionate formulated with hydrofluoroalkane in 4- to 11-year-olds with asthma

The systemic exposure of fluticasone propionate with hydrofluoroalkane propellant compared with chlorofluoro-carbon propellant and the effect of fluticasone propionate hydrofluoroalkane on 24-hour urinary cortisol in children aged 4 to 11 years with asthma were evaluated. Study 1 was an open-label, 2-way crossover study in which 16 subjects were randomized to 7.5 days each of fluticasone propionate hydrofluoroalkane 88 mug twice a day or fluticasone propionate chlorofluorocarbon 88 mug twice a day. In study 2, 63 subjects received 13.5 days of placebo followed by 27.5 days of fluticasone propionate hydrofluoroalkane 88 mug twice a day. The main outcome measure for study 1 was the difference between fluticasone propionate hydrofluoroalkane and fluticasone propionate chlorofluorocarbon in fluticasone propionate AUC(last) (area under the plasma fluticasone propionate concentration-time curve from zero up to the last quantifiable plasma concentration), and for study 2, 24-hour overnight urinary cortisol excretion. In study 1, fluticasone propionate systemic exposure was significantly lower (55%) with hydrofluoroalkane metered dose inhaler compared with chlorofluorocarbon metered dose inhaler. Study 2 showed no statistically significant changes in 24-hour overnight urinary cortisol excretion and no relationship to fluticasone propionate systemic exposure at this dose. The results of these 2 studies showed that in children aged 4 to 11 years with asthma, fluticasone propionate hydrofluoroalkane has lower systemic exposure compared with chlorofluorocarbon and no hypothalamic-pituitary-adrenal axis effects as measured by 24-hour urinary cortisol excretion.

The rejuvenated pressurised metered dose inhaler

The pressurised metered-dose inhaler (pMDI) has now been available for 50 years. Once regarded as an inefficient and difficult-to-use device, the technology has evolved significantly over the last few years, particularly since the introduction of novel formulations containing hydrofluoroalkane (HFA) propellants. Many modern HFA pMDIs deposit drug more efficiently in the lungs, impact less forcefully on the back of the throat and feel less cold than their chlorofluorocarbon pMDI counterparts. An improved understanding of technical factors makes it possible to design HFA pMDIs to have specific spray properties, particularly in terms of fine particle dose and spray velocity. Device technology has also progressed with the introduction of compact and convenient breath-actuated, breath-coordinated and velocity-modifying devices, which help patients to achieve a reliable lung dose. Although it faces competition from dry powder inhalers and possibly from novel soft-mist inhalers containing liquid formulations, the rejuvenated HFA pMDI is a device with a significant future for asthma, chronic obstructive pulmonary disease and wider treatment indications.

Reduction of eosinophils in small airways by inhaled steroids is insufficient in patients with adult asthma

BACKGROUND

Recent reports suggest that small airway as well as large airway involvement in asthma is important. We investigate the therapeutic effects of a meter-dose inhaler of chrolofluorocarbon-beclomethasone dipropionate (CFC-BDP) and dry-powder fluticasone (DP-FP).

METHODS

Lung specimens obtained at operation due for small size lung cancer in 16 asthmatic patients and 16 controls were evaluated immunohistochemically using antibodies of EG2 (eosinophil), AA1 (mast cell), CD68 (macrophage), and CD34 (pluripotent hematopoietic stem cell). We calculated the number of each cell type in 5 fields in the inner and outer areas of large airways (luminal diameter; > or =2 mm) and small airways (<2 mm) using computer software.

RESULTS

In asthmatic patients eosinophils were significantly increased in both inner and outer areas of small airways and the number of CD34+ cells was significantly elevated in inner areas as compared with controls. Although the density of eosinophils in the inner area of large airways was significantly suppressed (p < 0.02), there was no such suppression in the inner areas of small airways in asthmatic patients treated with CFC-BDP or DP-FP.

CONCLUSIONS

It was speculated that inhaled CFC-BDP and DP-FP might deposit mainly in large airways and fail to fully reach small airways, consequently allowing eosinophilic inflammation to continue in small airways.

Pharmacologic characteristics and adrenal suppression with newer inhaled corticosteroids: A comparison of ciclesonide and fluticasone propionate

BACKGROUND

Inhaled corticosteroids (ICSs) are the most potent anti-inflammatory choice for patients with asthma. Selecting the most appropriate ICS for a patient requires a thorough understanding of the pharmacologic properties of each drug.

OBJECTIVE

This review details the pharmacologic properties of ciclesonide (CIC) and fluticasone propionate (FP) and reviews the available data on suppression of the hypothalamic-pituitary-adrenal axis as a measure of systemic exposure and safety profile.

METHODS

Clinical studies and case reports were identified through a MEDLINE and EMBASE search of English-language articles. The databases were searched for the years 1990 to April 2005 using the terms ciclesonide, fluticasone, ICS, and adrenal suppression. All studies were clinical trials of pharmacologic properties of the ICSs in humans.

RESULTS

A total of 1082 articles were identified. CIC and FP are 2 of the most potent ICSs. Both have high receptor-binding affinities (12 times and 18 times that of dexamethasone, respectively), and both may provide enhanced respiratory effects through a prolonged pulmonary residence time. The CIC metered dose inhaler dispenses smaller and more highly respirable particles than FP (1.1-2.1 pm vs 2.8-3.2 microm, respectively). Therefore, a greater percentage of administered CIC is topically deposited in the lungs (52% vs 12% to 13% for FP). CIC is delivered as an inactive parent compound, which is converted to its active metabolite, desisobutyryl-CIC (des-CIC), by esterases in the airways. More than 50% of a dose of CIC is deposited and distributed evenly throughout the lungs of healthy adults; lipid conjugation in the lung also may increase lung residence time. On entering the systemic circulation, both corticosteroids are rapidly cleared by the liver (elimination half-life of 3.5 hours for CIC vs 7.8 hours for FP). However, plasma protein binding is greater with CIC/des-CIC (99%/ approximately 99%) than FP (90%), resulting in reduced amounts of des-CIC (<I%) versus FP (10%) circulating free in the plasma. Although studies of low or medium doses of FP have produced conflicting results, high doses of FP (>660 pg/d) may result in adrenal suppression. CIC has not been reported to produce any significant adrenal suppression throughout its studied dose range (up to 1280 micro/d).

CONCLUSIONS

A review of the literature suggests that CIC, as compared with FP, achieves greater pulmonary deposition, causes fewer adverse oropharyngeal effects, deposits less biologically active drug in the systemic circulation, and has less potential for adrenal suppression.

Fluticasone propionate HFA-134a pressurized metered-dose inhaler in adolescents and adults with moderate to severe asthma

In this randomized, double-blind, placebo-controlled trial, 397 patients with moderate to severe asthma, previously treated with bronchodilators alone, received fluticasone propionate 88, 220, or 440 microg twice daily, or placebo via metered dose inhaler (MDI) for 12 weeks. Mean change from baseline to endpoint in pre-dose percent predicted forced expiratory volume in one second (FEV1) was greater (p < 0.001) in each fluticasone propionate group (9.0%, 88 microg bid; 9.8%, 220 microg bid; 11.2%, 440 microg bid) versus placebo (3.4%). Morning and evening peak expiratory flow (PEF), asthma symptoms, and supplemental albuterol use also improved in all fluticasone propionate groups versus placebo. The incidence of adverse events and 24-hour urine cortisol excretion rates were similar between active treatments and placebo.

Development and performance of a new hydrofluoroalkane (HFA 134a)-based metered dose inhaler (MDI) of salmeterol

In response to the Montreal Protocol, a salmeterol (Serevent) metered dose inhaler (MDI) has been developed containing the non-chlorofluorocarbon propellant, hydrofluoroalkane 134a (HFA), to replace the marketed Serevent chlorofluorocarbon (CFC) propellant MDI. This paper details the pharmaceutical assessment of salmeterol HFA MDI and confirms that this product meets the current Committee for Proprietary Medicinal Products regulatory requirements, and is comparable to the CFC MDI in product performance. Criteria investigated included fine particle mass (FPM), dose delivery and uniformity, priming requirements and simulated-use-testing. Dose delivery was unaffected by changing product orientation during storage. The mean dose delivered per actuation ranged from 21.3 to 22.4 microg, and all individual doses were within the +/-25% defined limits of the target ex-actuator dose of 21 microg. The FPM results, defined as the mass of particles between 1.1 and 4.7 microm in diameter (the sum of the mass deposited on stages 3-5 of the Andersen Cascade Impactor), were similar for the HFA and CFC products. The mean FPM values of the two HFA clinical batches were 8.7 and 10.1 microg, covering the values obtained during the development, and the one of the CFC clinical batch was 10.0 microg. Comparability in aerosol characteristics was also demonstrated when the salmeterol HFA inhaler was tested using a large volume spacer (Volumatic).

Effects of high-dose inhaled fluticasone propionate on the hypothalamic-pituitary-adrenal axis in asthmatic patients with severely impaired lung function

BACKGROUND

The effects of high-dose fluticasone propionate therapy on dynamic cortisol stimulation in severe asthma are unknown.

OBJECTIVE

To evaluate the human corticotropin-releasing factor (hCRF)-stimulated plasma cortisol response to fluticasone propionate therapy in severe asthmatic patients with impaired airway caliber (forced expiratory volume in 1 second [FEV1] < 60% of predicted) and in control subjects.

METHODS

Ten severe asthmatic patients (mean FEV1, 47% of predicted) and 10 controls (mean FEV1, 104% of predicted) received fluticasone propionate, 2,000 microg/d, via a 750-mL primed spacer for 2 weeks. Plasma cortisol levels before and after hCRF stimulation and overnight 10-hour urinary cortisol excretion corrected for creatinine concentration (OUCC) were measured at baseline after washout and 12 hours after the last dose of fluticasone propionate.

RESULTS

Baseline values before fluticasone propionate use were not significantly different in asthmatic patients vs controls for plasma cortisol before and after hCRF stimulation and OUCC. Comparing values at baseline vs after fluticasone propionate use, there was no significant suppression of plasma cortisol levels before (378.2 vs 357.4 nmol/L) or after (510.5 vs 507.9 nmol/L) hCRF stimulation or OUCC (8.2 vs 7.5 nmoL/mmoL) in asthmatic patients. In controls, all outcomes were significantly suppressed comparing values before vs after fluticasone propionate therapy: plasma cortisol levels before (423.5 vs 200.2 nmol/L; P = .002) and after (503.5 vs 291.1 nmol/L; P = .001) hCRF stimulation and OUCC (6.5 vs 2.4 nmol/mmol; P = .002).

CONCLUSION

Patients with severe persistent asthma and impaired airway caliber seem to be protected from developing systemic adverse effects with high-dose fluticasone propionate therapy, as evaluated by basal and dynamic measures of hypothalamic-pituitary-adrenal axis activity.

The presence of emphysema does not affect the systemic bioactivity of inhaled fluticasone in severe chronic obstructive pulmonary disease

AIMS

To assess the systemic bioactivity of fluticasone proprionate (FP) 2000 micro g daily on sensitive adrenal and bone markers in severe chronic obstructive pulmonary disease (COPD) patients with or without significant emphysema.

METHODS

Ten patients without emphysema (COPD group: age 55 years, FEV(1) 51% predicted and DL(CO) 83% predicted) and 10 patients with emphysema (COPDE group: age 59 years, FEV(1) 43% predicted and DL(CO) 49% predicted) received FP 2000 micro g daily via a spacer for 2 weeks. There was a 1-week washout period prior to FP treatment where patients were given salmeterol and oxitropium, after stopping their usual inhaled corticosteroids for the duration of the study. Measurements including overnight 10 h urinary cortisol excretion corrected for creatinine (OUCC) and serum osteocalcin concentrations were performed at baseline following washout and after 2 weeks of FP.

RESULTS

Values for OUCC and serum osteocalcin concentrations pre- and post-FP were not significantly different between the COPD and COPDE groups. There was significant suppression of OUCC (nmol mmol(-1)) by FP treatment within the COPD group (P = 0.03): 7.86 vs 4.64 (95% CI on the difference 0.47, 5.98), and within the COPDE group (P = 0.006): 7.13 vs 4.27 (95% CI on the difference: 1.03, 4.69). Likewise, there was significant suppression of osteocalcin concentration (nmol l(-1)) by FP treatment within the COPD group (P = 0.04): 7.24 vs 6.34 (95% CI on the difference: 0.01, 1.78), and within the COPDE group (P = 0.03): 6.92 vs 5.72 (95% CI on the difference: 0.12, 2.29).

CONCLUSIONS

Severe COPD patients who are receiving high dose FP are susceptible to the development of systemic adverse effects, irrespective of the presence of emphysema.

The formulation and evaluation of a CFC-free budesonide pressurised metered dose inhaler

Although dry powder inhalers are well established for the delivery of corticosteroids, the pressurised metered dose inhaler remains the preferred and most cost effective presentation. To design an HFA solution formulation which matched marketed CFC products (Pulmicort and Desonac DA) two elements of the Chiesi Modulite system, the addition of a non-volatile component and the actuator orifice diameter, were varied. These variables, which were shown by in vitro tests to influence the fine particle dose and its mean particle size in different ways, could be permuted to give an aerosol cloud with size characteristics very close to the comparator products. The likelihood that this would confer clinical equivalence is reinforced by a pharmacokinetic analysis which showed that the chosen HFA solution formula gave similar systemic absorption from the lung as Pulmicort. The equivalence in aerosol characteristics was sustained when the pressurised metered dose inhalers (pMDIs) were used with spacers. The Chiesi Jet and the AstraZeneca Nebuhaler, when used with their respective pMDIs, reduced likely oropharyngeal deposition to the same extent and gave a similar increase in the fine particle dose.

Aerodynamic particle size analysis of aerosols from pressurized metered-dose inhalers: comparison of Andersen 8-stage cascade impactor, next generation pharmaceutical impactor, and model 3321 Aerodynamic Particle Sizer aerosol spectrometer

The purpose of this research was to compare three different methods for the aerodynamic assessment of (1) chloroflurocarbon (CFC)--fluticasone propionate (Flovent), (2) CFC-sodium cromoglycate (Intal), and (3) hydrofluoroalkane (HFA)--beclomethasone dipropionate (Qvar) delivered by pressurized metered dose inhaler. Particle size distributions were compared determining mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD), and fine particle fraction <4.7 microm aerodynamic diameter (FPF(<4.7 microm)). Next Generation Pharmaceutical Impactor (NGI)-size distributions for Flovent comprised finer particles than determined by Andersen 8-stage impactor (ACI) (MMAD = 2.0 +/- 0.05 micro m [NGI]; 2.8 +/- 0.07 microm [ACI]); however, FPF(<4.7 microm) by both impactors was in the narrow range 88% to 93%. Size distribution agreement for Intal was better (MMAD = 4.3 +/- 0.19 microm (NGI), 4.2 +/- 0.13 microm (ACI), with FPF(<4.7 microm) ranging from 52% to 60%. The Aerodynamic Particle Sizer (APS) undersized aerosols produced with either formulation (MMAD = 1.8 +/- 0.07 micro m and 3.2 +/- 0.02 micro m for Flovent and Intal, respectively), but values of FPF(<4.7 microm)from the single-stage impactor (SSI) located at the inlet to the APS (82.9% +/- 2.1% [Flovent], 46.4% +/- 2.4% [Intal]) were fairly close to corresponding data from the multi-stage impactors. APS-measured size distributions for Qvar (MMAD = 1.0 +/- 0.03 micro m; FPF(<4.7 micro m)= 96.4% +/- 2.5%), were in fair agreement with both NGI (MMAD = 0.9 +/- 0.03 micro m; FPF(<4.7 microm)= 96.7% +/- 0.7%), and ACI (MMAD = 1.2 +/- 0.02 microm, FPF(<4.7 microm)= 98% +/- 0.5%), but FPF(<4.7 microm) from the SSI (67.1% +/- 4.1%) was lower than expected, based on equivalent data obtained by the other techniques. Particle bounce, incomplete evaporation of volatile constituents and the presence of surfactant particles are factors that may be responsible for discrepancies between the techniques.

The influence of inhaler selection on efficacy of asthma therapies

Many different devices are available to aid inhalational drug delivery. Although each device is claimed to have advantages over its rivals, the evidence to support greater efficacy of a particular device is scanty. Most comparative studies are underpowered or flawed in their design. They may use inappropriate end-points, or involve healthy subjects, whose response may be very different from the patient with acute severe asthma. The dosage of drug used in a trial may be at the shallow part of the dose-response curve, masking differences in devices. Only in a few cases have clinical trials detected a significant difference between devices, and trials have rarely taken patient preference into account. The most efficacious device in practice is likely to be the one that the patient will use regularly and in accordance with a health care workers' recommendations.

Effects of fluticasone vs. fluticasone/salmeterol on airway calibre and airway hyperresponsiveness in mild persistent asthma

AIMS

Inhaled corticosteroids alone or in combination with long acting beta2-agonists are indicated for use in mild persistent asthmatics. We set out to evaluate effects on airway hyperresponsiveness (AHR) and airway calibre using hydrofluoroalkane fluticasone/salmeterol (FP/SM) vs. double the dose of fluticasone alone (FP).

METHODS

Fourteen mild persistent asthmatics completed a randomized double-blind crossover study with 1-week run-in and washout periods prior to treatments. Subjects received 3 weeks of FP 250 microg or FP 125 microg/SM 25 microg as 1 puff twice daily. Methacholine PD20 and lung function were measured after both baseline and treatment periods.

RESULTS

There were no significant differences in baseline values prior to randomized treatments. Compared with pooled baseline, FP/SM and FP conferred improvements (P < 0.05) on methacholine PD20: 2.5 (95% confidence interval 1.7, 3.2) and 1.6 (0.8-2.3) doubling dose improvements, respectively; between FP/SM vs. FP there was a 0.9 (0.4, 1.4) doubling dose difference (P < 0.05). For forced expiratory volume in 1 s (FEV1), forced mid-expiratory flow (FEF25-75) and morning peak expiratory flow (PEF), FP/SM but not FP conferred improvements (P < 0.05) compared with pooled baseline, with FP/SM being greater than FP (P < 0.05): differences in FEV1 of 7.2% (3.8, 10.6) predicted, FEF25-75 of 11.2% (6.3, 16.1) predicted, and morning PEF of 17 L x min(-1)(1-32).

CONCLUSIONS

FP/SM conferred improvements on AHR and airway calibre, while twice the dose of FP improved only AHR in patients with mild asthma. The differential effects of FP/SM and FP suggest separate but complementary actions of the two moieties on airway inflammation and smooth muscle stabilization. This may explain the beneficial effects of combination inhalers on exacerbations.

Airway wall remodeling: friend or foe?

Airway wall remodeling is well documented for asthmatic airways and is believed to result from chronic and/or short-term exposure to inflammatory stimuli. Airway wall remodeling can contribute to airway narrowing as well as to the airway hyperresponsiveness, which is a characteristic abnormality in asthma. However, the potential for airway narrowing could be much worse if it were not for some of the protective effects of remodeling that may help to limit airway narrowing in asthmatic patients. This minireview discusses the evidence for airway wall remodeling and its effects, friend and/or foe, on airway narrowing in asthmatic patients.

Reverse water-in-fluorocarbon emulsions for use in pressurized metered-dose inhalers containing hydrofluoroalkane propellants

Pulmonary administration of drugs has demonstrated numerous advantages in the treatment of pulmonary diseases due to direct targeting to the respiratory tract. It enables avoiding the first pass effect, reduces the amount of drugs administered, targets drugs to specific sites and reduces their side effects. Reverse water-in-fluorocarbon (FC) emulsions are potential drug delivery systems for pulmonary administration using pressurized metered-dose inhalers (pMDI). The external phase of these emulsions consists of perfluorooctyl bromide (PFOB, perflubron), whereas their internal phase contains the drugs solubilized or dispersed in water. These emulsions are stabilized by a perfluoroalkylated dimorpholinophosphate (F8H11DMP), i.e. a fluorinated surfactant. This study demonstrates the possibility of delivering a reverse fluorocarbon emulsion via the pulmonary route using a CFC-free pMDI. Two hydrofluoroalkanes (HFAs) (Solkane(R) 134a and Solkane(R) 227) were used as propellants, and various solution (or emulsion)/propellant ratios (1/3, 1/2, 2/3, 1/1, 3/2, 3/1 v/v) were investigated. The insolubility of water (with or without the fluorinated surfactant F8H11DMP) in both HFA 227 and HFA 134a was demonstrated. PFOB and the reverse emulsion were totally soluble or dispersible in all proportions in both propellants. This study demonstrated also that the reverse FC emulsion can be successfully used to deliver caffeine in a homogeneous and reproducible way. The mean diameter of the emulsion water droplets in the pressured canister was investigated immediately after packaging and after 1 week of storage at room temperature. Best results were obtained with emulsion/propellant ratios comprised between 2/3 and 3/2, and with HFA 227 as propellant.

A comparison of the efficacy and tolerability of single doses of HFA 134a albuterol and CFC albuterol in mild-to-moderate asthmatic patients

BACKGROUND

After the signing of the Montreal Protocol in 1987, new propellants for use in pressurized metered-dose inhalers that are non-ozone-depleting have been developed.

OBJECTIVE

This study was designed to compare the efficacy and tolerability of single doses of albuterol/HFA 134a with albuterol/CFC and to demonstrate a dose-response among the different doses of both formulations.

METHODS

A single-center, randomized, double-blind, placebo-controlled, cross-over study. Sixty-three adolescent and adult asthmatic patients were randomized to receive at separate treatment visits single doses via a pressurized metered-dose inhaler of either placebo/hydrofluoroalkane (HFA) 134a; 100 microg, 200 microg, or 400 microg albuterol/HFA 134a; 100 microg or 200 microg albuterol/chlorofluorocarbon (CFC). Triplicate measurements of forced expiratory volume in 1 second (FEV1) were made immediately before dosing and 15 minutes, 30 minutes, 1, 2, 3, 4, 5, and 6 hours postdose. The primary efficacy variables were area under the entire 6-hour FEV1 curve, relative to baseline subtracted from the area above baseline (AUC(0-6)) and peak effect (derived from serial FEV1 measurements).

RESULTS

Analysis of AUC(0-6) and peak effect showed that all doses of albuterol had a significantly greater effect than placebo (HFA 134a propellant). Comparisons of the two formulations at 100 microg and 200 microg showed no difference in AUC(0-6) (100 microg, -0.23 Lhr, P = 0.114 and 200 microg -0.08 Lhr, P = 0.590) or in peak effect, percentage of baseline (100 microg, -1.3%, P = 0.354 and 200 microg, 0.17%, P = 0.902). There were no differences seen among formulations in the incidence of adverse events or with any of the other safety parameters, including electrocardiograms, vital signs, clinical laboratory assessments, and asthma exacerbations.

CONCLUSIONS

The study demonstrated comparability in terms of efficacy and safety between albuterol/HFA 134a and albuterol/CFC.

Albuterol HFA is as effective as albuterol CFC in preventing exercise-induced bronchoconstriction

BACKGROUND

Secondary to the phase-out of chlorofluorocarbons (CFCs), the albuterol (Ventolin, GlaxoSmithKline, Uxbridge, Middlesex, United Kingdom) pressurized metered-dose inhaler (MDI) has been formulated in a non-ozone-depleting propellant, hydrofluoroalkane (HFA) 134a.

OBJECTIVE

To compare the efficacy of albuterol HFA to albuterol CFC and placebo HFA in protecting patients from exercise-induced bronchospasm (EIB).

METHODS

Randomized, double-blind, placebo-controlled, three-way crossover study in patients with documented EIB. Patients (n = 24) aged 18 to 45 years old received albuterol HFA or albuterol CFC, (total dose of 180 microg ex-actuator), or placebo HFA via an MDI, 30 minutes before a standardized exercise challenge. Serial forced expiratory volume in 1 second (FEV1) measurements were made 5 minutes before exercise and 5, 10, 15, 20, 25, 30, and 60 minutes postexercise. The primary outcome measure was the maximum percentage fall in FEV1 over the 60 minutes after exercise.

RESULTS

The adjusted mean maximum percentage falls in FEV1 postexercise for albuterol HFA and CFC groups were 15.4% and 14.9%, respectively. The two formulations were comparable with a treatment difference of -0.5% (P = 0.848; 95% confidence interval, -5.3 to 4.4%). When compared with the fall in FEV1 for placebo (33.7%), both active treatments demonstrated a significantly smaller fall in FEV1 postexercise (P < 0.001). Safety profiles were similar among the three treatment groups.

CONCLUSIONS

The results provide assurance to prescribers that the formulation of albuterol in the non-ozone-depleting propellant HFA 134a has not affected its efficacy in the treatment of EIB in asthmatic patients. Single doses of albuterol HFA and CFC from an MDI are comparable in terms of efficacy and safety on a microgram per microgram basis.