Expert consensus on an in vitro approach to assess pulmonary fibrogenic potential of aerosolized nanomaterials

The increasing use of multi-walled carbon nanotubes (MWCNTs) in consumer products and their potential to induce adverse lung effects following inhalation has lead to much interest in better understanding the hazard associated with these nanomaterials (NMs). While the current regulatory requirement for substances of concern, such as MWCNTs, in many jurisdictions is a 90-day rodent inhalation test, the monetary, ethical, and scientific concerns associated with this test led an international expert group to convene in Washington, DC, USA, to discuss alternative approaches to evaluate the inhalation toxicity of MWCNTs. Pulmonary fibrosis was identified as a key adverse outcome linked to MWCNT exposure, and recommendations were made on the design of an in vitro assay that is predictive of the fibrotic potential of MWCNTs. While fibrosis takes weeks or months to develop in vivo, an in vitro test system may more rapidly predict fibrogenic potential by monitoring pro-fibrotic mediators (e.g., cytokines and growth factors). Therefore, the workshop discussions focused on the necessary specifications related to the development and evaluation of such an in vitro system. Recommendations were made for designing a system using lung-relevant cells co-cultured at the air–liquid interface to assess the pro-fibrogenic potential of aerosolized MWCNTs, while considering human-relevant dosimetry and NM life cycle transformations. The workshop discussions provided the fundamental design components of an air–liquid interface in vitro test system that will be subsequently expanded to the development of an alternative testing strategy to predict pulmonary toxicity and to generate data that will enable effective risk assessment of NMs

MULTIPLE PATH PARTICLE DOSIMETRY FOR PREDICTION OF MOUSE LUNG DEPOSITION OF NANOAEROSOL PARTICLES

Nanoaerosolized particle (dia.\u3c200 \u3enm) antibiotic inhalation therapy was tested to treat pneumonic tularemia in mice caused by Francisella novicida infection. Very limited experimental techniques are available to properly estimate inhaled doses and distribution of the drug inside the mouse lungs. To overcome this problem, computational simulation of particle deposition based on the Multiple Path Particle Dosimetry (MPPD) model was employed to simulate in vivo experimental conditions which included nasal breathing with whole body exposure to the antibiotic in the form of nano-aerosolized medicine. The deposition results were compared with several in vivo experimental data reported in literature; and satisfactory agreements were found. Comparing with in vivo experimental data, regional deposition results are very close with ±1015% variations. After testing application of the MPPD model, the total inhaled doses of levofloxacin encapsulated into nanoliposomes were estimated which take into account distribution of sizes of nanoaersol particles. Thus, we have demonstrated that MPPD can be used to model the deposition of nanoaerosol particles in mice

PARTICLE SHAPE ENGINEERING FOR IMPROVED DRUG DELIVERY TO PERIPHERAL LUNGS BY NON-INVASIVE ROUTE

Inhalation of therapeutics has been gaining importance owing to immense advantages offered by pulmonary route and have attracted significant advancements in the pharmaceutical field. However, pulmonary drug delivery has been challenging because of the complexity of the respiratory tract and the existing defense mechanism. The pulmonary drug delivery has experienced advances in approaches and strategies to combat the existing challenges by tailoring the physicochemical properties of the delivery carriers and enabling both localized as well as systemic delivery. Pulmonary drug delivery is governed by several biophysical parameters of the delivery carriers such as particle size, shape, density, charge, and surface modifications. Although much attention has been garnered for other parameters particle shape effects have been less likely explored. In this exploration we studied the impact of particle shape on the aerodynamic properties, ability to escape macrophage uptake and therapeutic effectiveness of particles against lung cancer. Interestingly, the results of in-vitro lung deposition demonstrated improved aerodynamic properties of the rod-shaped with high aspect ratio as compared to spherical particles. Results of macrophage uptake demonstrate that high aspect ratio particles were internalized less when compared to spherical particles. On the contrary, results of cellular uptake by small cell lung cancer cells revealed preferential uptake of rod-shaped particles than spherical particles. The results were further validated by in-vitro tumor simulation studies wherein rod-shaped particles displayed enhanced anti-tumorigenic activity against spheres. Moreover, the high aspect ratio particles also demonstrated diminished cardiotoxicity activity; adverse effect of DOX limiting its therapeutic use. These results provide valuable insights about influence of particle shape for designing inhalable therapeutics

Empirical modeling of the fine particle fraction for carrier-based pulmonary delivery formulations

In vitro study of the deposition of drug particles is commonly used during development of formulations for pulmonary delivery. The assay is demanding, complex, and depends on: properties of the drug and carrier particles, including size, surface characteristics, and shape; interactions between the drug and carrier particles and assay conditions, including flow rate, type of inhaler, and impactor. The aerodynamic properties of an aerosol are measured in vitro using impactors and in most cases are presented as the fine particle fraction, which is a mass percentage of drug particles with an aerodynamic diameter below 5 µm. In the present study, a model in the form of a mathematical equation was developed for prediction of the fine particle fraction. The feature selection was performed using the R-environment package “fscaret”. The input vector was reduced from a total of 135 independent variables to 28. During the modeling stage, techniques like artificial neural networks, genetic programming, rule-based systems, and fuzzy logic systems were used. The 10-fold cross-validation technique was used to assess the generalization ability of the models created. The model obtained had good predictive ability, which was confirmed by a root-mean-square error and normalized root-mean-square error of 4.9 and 11%, respectively. Moreover, validation of the model using external experimental data was performed, and resulted in a root-mean-square error and normalized root-mean-square error of 3.8 and 8.6%, respectively.Published versio

DissolvIt : development and validation of a new in vitro dissolution apparatus for dry powder aerosols

Today there are no recommended dissolution methods for use in the development of new inhalable drugs. In the absence of such tailored methods, standard dissolution test methods from oral- or skin administration routes are used instead. Such methods are obviously not designed to resemble the lung environment. There is also a growing demand for the next level of in vitro methods that may correlate the generated in vitro data with in vivo data for tested substances, that is to demonstrate in vitro-in vivo correlation. Being able to predict in vivo data as well as clinical outcomes, provides enormous potential in minimizing animal experiments, reduce cost, and shorten time to optimize the drug development process. The aim of this thesis was to develop and validate a new in vitro dissolution test method to be used for dry powder aerosols. One important task in the strategy was to make the apparatus relevant to the physiology of the lung. The DissolvIt was developed. Particles were deposited with the aerosol generator PreciseInhale on glass cover slips. At the start of an experiment, the particles on a glass cover slip are contacted with a mucus simulant. Particles are dissolved into the mucus simulant and absorbed via a hydrophilic membrane to a blood simulant pumped along the opposite side of the membrane. Samples of the blood simulant are repeatedly collected over time and are analyzed with liquid chromatography-mass spectrometry/mass spectrometry for the active pharmaceutical ingredient(s) tested. It was shown that DissolvIt discriminates between different active pharmaceutical ingredients and generates clinical-like data in the form of absorption curves to the perfusate containing Cmax and Tmax. It was also shown that the particle dose and deposition pattern affect the dissolution process, but that PreciseInhale allow sufficient control of the deposition pattern and dose, to minimize a negative influence on dissolution. The composition of the DissolvIt mucus simulant was evaluated against more complex variants such as simulated lung fluid and Survanta, but the simulant chosen as standard for DissolvIt was based on phosphate buffer containing polyethylene oxide and L alpha phosphatidylcholine. Through physiologically based pharmaco-kinetic modeling, the standard mucus was shown to generate pharmacokinetic values closest to the in vivo profile of the same drug. The lipid content of the mucus simulant was varied, but a level of 0.4 % was chosen because the most stable data was generated and 0.4 % is close to the mean value of the lipid content in the lung lining layer. DissolvIt was also compared to the paddle over disc- and modified Transwell dissolution methods. Two parameters from the relevant lung physiology are hard to mimic in vitro; the sparse dose deposition over the lung surface and the air-blood barrier thickness. However, in a comparison with data from the ex vivo rat lung, the DissolvIt produced results, regarding both design and pharmacokinetic output such as first half-time of absorption, that most resembled data from the living lung compared with paddle over disc and modified Transwell methods. In conclusion, the DissolvIt is a newly developed in vitro dissolution apparatus tailored for inhalable drugs, with a potential to be established as a recommended test method in the drug development process, also with respect to in vitro-in vivo correlation

Aerospace Medicine and Biology. A continuing bibliography with indexes

This bibliography lists 244 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1981. Aerospace medicine and aerobiology topics are included. Listings for physiological factors, astronaut performance, control theory, artificial intelligence, and cybernetics are included

The effect of short-term changes in air pollution on respiratory and cardiovascular morbidity in Nicosia, Cyprus.

Presented at the 6th International Conference on Urban Air Quality, Limassol, March, 2007. Short-paper was submitted for peer-review and appears in proceedings of the conference.This study investigates the effect of daily changes in levels of PM10 on the daily volume of respiratory and cardiovascular admissions in Nicosia, Cyprus during 1995-2004. After controlling for long- (year and month) and short-term (day of the week) patterns as well as the effect of weather in Generalized Additive Poisson models, some positive associations were observed with all-cause and cause-specific admissions. Risk of hospitalization increased stepwise across quartiles of days with increasing levels of PM10 by 1.3% (-0.3, 2.8), 4.9% (3.3, 6.6), 5.6% (3.9, 7.3) as compared to days with the lowest concentrations. For every 10μg/m3 increase in daily average PM10 concentration, there was a 1.2% (-0.1%, 2.4%) increase in cardiovascular admissions. With respects to respiratory admissions, an effect was observed only in the warm season with a 1.8% (-0.22, 3.85) increase in admissions per 10μg/m3 increase in PM10. The effect on respiratory admissions seemed to be much stronger in women and, surprisingly, restricted to people of adult age

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 275)

This bibliography lists 321 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1985