Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AEROSOLS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed2002

Development of a gas chromatographic/ion trap mass spectrometric method for the determination of levoglucosan and saccharidic compounds in atmospheric aerosols. Application to urban aerosols.

We developed and validated a gas chromatographic/ion trap mass spectrometric method for the determination of levoglucosan and the related monosaccharide anhydrides, mannosan, galactosan and 1,6-anhydro-beta-D-glucofuranose in urban atmospheric aerosols collected on quartz fiber filters. The method is based on extraction with dichloromethane-methanol (80 : 20, v/v), trimethylsilylation, multiple reaction monitoring in the tandem mass spectrometric mode using the ion at m/z 217, and the use of an internal standard calibration procedure with the structurally related compound methyl beta-L-arabinopyranoside. In addition, the method allows the quantification of other saccharidic compounds, arabitol, mannitol, glucose, fructose, inositol and sucrose, which were found to be important in summer aerosols. The recovery of levoglucosan was estimated by spiking blank filters and was better than 90%. The precision evaluated by analyzing parts of the same filters was about 2% for the monosaccharide anhydrides and 7% for the other saccharidic compounds in the case of a winter aerosol sample, and the corresponding values for a summer aerosol sample were 5% and 8%. The method was applied to urban PM(10) (particulate matter of <10 microm aerodynamic diameter) aerosols collected at Ghent, Belgium, during a 2000-2001 winter and a 2001 summer episode and revealed interesting seasonal variations. While monosaccharide anhydrides were relatively more important during the winter season owing to wood burning, the other saccharidic compounds were more prevalent during the summer season, with some of them, if not all, originating from the vegetation.

Aerosols↗
PubMed1990

Strategies for aerosol therapy of alpha 1-antitrypsin deficiency by the aerosol route.

Alpha 1-antitrypsin (AAT) deficiency is a genetic disease in which low serum and lung levels of the antiprotease AAT cause a deficiency of the anti-elastase defensive screen of the lower respiratory tract such that neutrophil elastase is free to degrade the connective tissue of the lung, eventually resulting in emphysema. Intravenous AAT infusion therapy restores lung levels of AAT, but is inefficient, costly and a demanding form of therapy. As an alternative, we evaluated aerosol delivery of human plasma AAT (pAAT) and recombinant DNA-produced AAT (rAAT), as a means of providing anti-elastase protection to the lower respiratory tract. In vitro studies demonstrated that both pAAT and rAAT can be aerosolized into droplets suitable for alveolar deposition without loss of antiprotease activity. When administered by aerosol to individuals with AAT deficiency, pAAT and rAAT each significantly raised lung epithelial lining fluid levels of AAT and anti-neutrophil elastase capacity, with the likelihood that twice daily administration of 100 mg of either form would result in normalization of lung anti-elastase defenses at the alveolar surface. Studies in sheep further demonstrated that the aerosolized pAAT and rAAT were each able to pass through alveolar epithelium and gain access to the interstitial compartment of the lung, thus increasing anti-elastase defenses of the lung interstitium. Therapy was safe and well tolerated in all cases. Aerosol therapy with pAAT or rAAT is a safe, feasible, and likely a biochemically efficacious alternative to intravenous AAT augmentation therapy and merits further long-term studies for clinical therapy.

Administration, Inhalation↗
PubMed2003

Fractional contribution of lung, nasal and gastrointestinal absorption to the systemic level following nose-only aerosol exposure in rats: a case study of 3.7- micro m fluorescein aerosols.

Because absorption takes place from multiple sites of aerosol deposition, it is generally difficult to interpret systemic levels following nose-only inhalation in laboratory rodents. Therefore, this study attempted to determine the fractional contribution of lung, nasal and gastrointestinal (GI) absorption to the observed systemic level following nose-only aerosol exposure in rats using fluorescein as a model powder solute. Rats were treated orally with vehicle or activated charcoal, the latter diminishing GI absorption of fluorescein, and were subsequently nose-only exposed to 3.7- micro m fluorescein aerosols at 25.2 micro g/l(air) for 10 min. While fluorescein similarly disappeared from the lung at a half-life of 0.23 hr, its plasma concentrations in the charcoal-treated group were significantly lower than those in the charcoal-untreated (vehicle) group. This suggests that significant portions of fluorescein were transported by nasopharyngeal and tracheobronchial mucociliary clearances following aerosol exposure and were absorbed from the GI tract. Despite the lack of GI absorption in the charcoal-treated animals, it was estimated that this nose-only exposure of fluorescein allowed 25.7 and 82.5 micro g/kg of simultaneous lung and nasal deposition, respectively, followed by their absorption composing the observed systemic level in this group (AUC(0- infinity ) 137.49 ng/ml h). Thus, assuming linear pharmacokinetics of fluorescein, the extent of absorption (AUC(0- infinity )) due to such nasal deposit (82.5 micro g/kg) was estimated to be 47.00 ng/ml h using the AUC(0- infinity ) obtained in an independent study of intranasal powder insufflation at 34.5 micro g/kg in the charcoal-treated rats (AUC(0- infinity ) 19.66 ng/ml h). As a result, the AUC(0- infinity ) due to 25.7 micro g/kg of the lung deposit was deconvoluted to be 90.49 ng/ml h and finally, the absolute bioavailability (F%) of the "lung-region-specific" deposition and absorption of fluorescein was estimated to be 55.0%. It is observed therefore, that lung, nasal and GI absorption accounted for 24.2, 12.5 and 63.3% of the total fluorescein absorption, respectively, following nose-only exposure of 3.7- micro m aerosols. This study addresses the common methodological insufficiency of nose-only inhalation studies in rodents, which have been neglected in most cases, and provides the appropriate kinetic interpretation for their observed systemic level.

Administration, Inhalation↗
PubMed1983

Influence of elastase-induced emphysema and the inhalation of an irritant aerosol on deposition and retention of an inhaled insoluble aerosol in Fischer-344 rats.

The purpose of this study was to assess the effects of elastase-induced pulmonary emphysema and the inhalation of an irritant aerosol (Triton X-100, a nonionic surfactant similar to those used in a number of pressurized consumer products) on pulmonary deposition and retention of an insoluble test aerosol, 59Fe-labeled Fe2O3. Untreated rats or rats pretreated by intratracheal instillation with elastase were exposed to an aerosol of 59Fe-labeled Fe2O3 either 18 hr or 7 days after exposure to aerosolized Triton X-100 which was administered in doses of 20, 100, or 200 micrograms/g of lung. Rats pretreated with elastase had significantly lower pulmonary deposition of 59Fe than the untreated controls (p less than 0.005). Pulmonary deposition of Fe2O3 was unaffected by pretreatment with Triton X-100. Elastase treatment alone had no effect on retention of Fe2O3. Triton X-100 administered 18 hr prior to exposure of rats to Fe2O3 aerosol resulted in dose-related increases in whole-body retention of 59Fe. When rats were exposed to Triton X-100 7 days before exposure to Fe2O3, increased retention of 59Fe was noted only in those treated at the highest Triton X-100 dose level (200 micrograms/g).

Aerosols↗
PubMed2006

Determination of levoglucosan in atmospheric aerosols using high performance liquid chromatography with aerosol charge detection.

A sensitive method for analysis of levoglucosan (1,6-anhydro-beta,d-glucopyranose) and other monosaccharide anhydrides, compounds present in biomass combustion smoke, was investigated employing high-performance liquid chromatography (HPLC) with recently developed aerosol charge detection. Aerosol charge detection involves the conversion of the column effluent to an aerosol, which is charged to produce a current. Use of a cation-exchange column and a pure water eluent was found to separate levoglucosan and mannosan from other aerosol components with a detection limit of about 90 ng mL(-1) for levoglucosan or 5 ng injected. This method was demonstrated by successful analysis of aerosol filter samples from three locations.

Aerosols↗
PubMed2002

Treatment of aerosolized cowpox virus infection in mice with aerosolized cidofovir.

The Brighton strain of cowpox virus causes lethal bronchopneumonia when delivered as a small-particle (1 microm) aerosol to weanling BALB/c mice. We showed previously that this disease can be prevented or cured with one subcutaneous injection of cidofovir (HPMPC, Vistide). To determine whether even better results could be obtained by delivering the drug directly to the respiratory tract, we administered cidofovir by small-particle aqueous aerosol before or after aerosolized cowpox infection. In a series of five experiments, aerosol doses of 0.5-5 mg/kg were always more effective than 25 mg/kg and sometimes more effective than 100 mg/kg injected subcutaneously, as measured by changes in body and lung weight, lung viral titers, pulmonary pathology and survival. A cyclic analog ((1-[(S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl] cytosine) (cHPMPC) was less protective. The results suggest that aerosolized cidofovir would be effective for prophylaxis or early post-exposure therapy of human smallpox or monkeypox virus infection.

Administration, Inhalation↗
PubMed2006

Investigation of alpha-pinene + ozone secondary organic aerosol formation at low total aerosol mass.

We present a method for measuring secondary organic aerosol (SOA) production at low total organic mass concentration (COA) using proton-transfer reaction mass spectrometry (PTR-MS). PTR-MS provides high time resolution measurements of gas-phase organic species and, coupled with particle measurements, allows for the determination of aerosol yield in real time. This approach facilitates the measurement of aerosol production at low COA; in fact aerosol mass fractions can be measured during alpha-pinene consumption as opposed to only at the completion of gas-phase chemistry. The high time resolution data are consistent with both the partitioning theory of Pankow (Atmos. Environ. 1994, 28,185 and 189) and the previous experimental measurements. Experiments including the effect of UV illumination and NOx reveal additional features of alpha-pinene + ozone product photochemistry and volatility. The high time resolution data also elucidate aerosol production from alpha-pinene ozonolysis at COA < 10 microg m(-3) and show that extrapolations of current partitioning models to conditions of low COA significantly underestimate SOA production under dark, low-NOx conditions. However, extrapolations of current models overestimate SOA production under illuminated, higher-NOx conditions typical of polluted regional air masses.

Aerosols↗
PubMed2000

Measurement of the emission rate of an aerosol source--comparison of aerosol and gas transport coefficients.

A measuring method of the emission rate of an atmospheric pollutant source, based on the use of a tracer gas (helium) and developed in the case of a gaseous source, was tested for an aerosol source. The influence of both particle sedimentation and wall depositions was studied. The transport coefficients of the tracer gas and of alumina particles of various particle sizes (MMAD from 8 to 36 microns) were measured on a vertical axis close to the source, in a 71 m3 room swept by a piston flow. The measurements clearly demonstrated the predominant influence of sedimentation in the case of particles with aerodynamic diameters greater than 10 microns. Particle wall deposition was determined by measuring the gas and particle concentration decay in the ventilated room. To do this, a new tracing method using a fluorescent aerosol was developed. The measured aerosol deposition rates are much higher than those calculated from the formula of Corner for a cubical volume. Aerosol sedimentation and wall deposition are two phenomena limiting the use of a tracer gas to measure the aerosol emission rate. The chemical substances and materials used in work premises are likely to be released into the atmosphere and lead to the formation of pollutants. These emissions stem from either physical or chemical processes (evaporation of a solvent) or from mechanical processes (dispersion of oil droplets at the source of mists).

Aerosols↗
PubMed1987

Guinea pigs sublethally infected with aerosolized Legionella pneumophila develop humoral and cell-mediated immune responses and are protected against lethal aerosol challenge. A model for studying host defense against lung infections caused by intracellular pathogens.

We have employed the guinea pig model of L. pneumophila infection, which mimics Legionnaires' disease in humans both clinically and pathologically, to study humoral and cell-mediated immune responses to L. pneumophila and to examine protective immunity after aerosol exposure, the natural route of infection. Guinea pigs exposed to sublethal concentrations of L. pneumophila by aerosol developed strong humoral immune responses. By the indirect fluorescent antibody assay, exposed guinea pigs had a median serum antibody titer (expressed as the reciprocal of the highest positive dilution) of 32, whereas control guinea pigs had a median titer of less than 1. Sublethally infected (immunized) guinea pigs also developed strong cell-mediated immune responses. In response to L. pneumophila antigens, splenic lymphocytes from immunized but not control animals proliferated strongly in vitro, as measured by their capacity to incorporate [3H]thymidine. Moreover, immunized but not control guinea pigs developed strong cutaneous delayed-type hypersensitivity to intradermally injected L. pneumophila antigens. Sublethally infected (immunized) guinea pigs exhibited strong protective immunity to L. pneumophila. In two independent experiments, all 22 immunized guinea pigs survived aerosol challenge with one or three times the lethal dose of L. pneumophila whereas none of 16 sham-immunized control guinea pigs survived (p less than 0.0001 in each experiment). Immunized guinea pigs were not protected significantly from challenge with 10 times the lethal dose. Immunized but not control animals cleared the bacteria from their lungs. This study demonstrates that guinea pigs sublethally infected with L. pneumophila by the aerosol route develop strong humoral immune responses to this pathogen, develop strong cell-mediated immune responses and cutaneous delayed-type hypersensitivity to L. pneumophila antigens, are protected against subsequent lethal aerosol challenge, and are able to clear the bacteria from their lungs. The guinea pig model of L. pneumophila pulmonary infection is as an excellent one for studying general principles of host defense against pulmonary infections caused by intracellular pathogens.

Aerosols↗
PubMed1992

Formoterol suspension aerosol. Comparison with formoterol solution aerosol for 12 weeks in asthmatic patients.

UNLABELLED: Formoterol solution aerosol has proved to be a fast and long-acting beta 2-sympathicomimetic drug in many clinical trials. The physical stability, however, was such that storage needed to be at 4 degrees C to 8 degrees C before first use; afterwards, the aerosol could be used for another three months at room temperature. To improve the stability, new ways have been investigated to formulate ann aerosol with improved shelf life and thus more convenient storage conditions, which was reached with a formoterol suspension aerosol. Equivalent single doses between the two formulations revealed no differences in onset or duration of action. In a double-blind, randomized parallel group multicenter study, organized in the Netherlands, 186 patients with stable asthma and reversible airway obstruction were treated either with one puff of 12 micrograms twice daily of formoterol metered dose inhaler (MDI) supension (SP) or a same dose of solution (SL) aerosol for 12 weeks to study the efficacy and tolerability of both presentations after a longer period of use. The following criteria of effectiveness were used: the FEV1 values on the mornings of the control days at 0, +4, +8, and + 12 weeks, the peak flow values (PEF) in the mornings and in the evenings before, and 1/2 to 1 h after treatment, the number of asthma attacks at night and during the day, the number of extra puffs at night and during day, and the subjective impression of patients and investigator. RESULT: No statistically significant differences between the two formoterol preparations were found. There was no indication of tachyphylaxis. CONCLUSION: The results are consistent with the hypothesis that the biologic effects of formoterol when delivered from MDI containing the two different formulations of the drug are equivalent.

Administration, Intranasal↗
PubMed2000

A mouse model of aerosol-transmitted orthopoxviral disease: morphology of experimental aerosol-transmitted orthopoxviral disease in a cowpox virus-BALB/c mouse system.

OBJECTIVES: To determine the morphologic changes and disease progression of aerosolized cowpox virus infection in BALB/c mice and to ascertain the suitability of cowpox virus-infected BALB/c mice as a model of aerosol-transmitted, orthopoxviral respiratory disease. METHODS: BALB/c mice were inoculated with cowpox virus, Brighton strain, by aerosol or intranasal route. Mice were killed at specified times after inoculation, necropsied, and tissues were collected for routine histology, immunohistochemistry, and electron microscopy. RESULTS: Inoculation by both routes resulted in disease and death. Immunolabeled viral antigen and lesions predominated in the tissues associated with the inoculation route, that is, lungs, airways, trachea, and nasal passages and sinuses. Tracheitis was evident in the intranasally infected group only. Lesions were generally necrotizing and hemorrhagic, neutrophilic, and increased in extent and severity in a time-dependent fashion. Viral intracytoplasmic inclusion bodies, immunolabeled viral antigen, or virions were readily seen in epithelial tissues, smooth muscle cells of airways and vessels, fibroblasts, periosteal cells, perineural cells, and macrophages. Although the extension of infection appeared to be primarily direct, lesions suggesting hematogenous dissemination were occasionally noted in bone marrow and skin. Transmission electron microscopy demonstrated features of cell injury or death, virion assembly and maturation, and both A-type and B-type inclusions. CONCLUSIONS: Aerosol inoculation of BALB/c mice with cowpox virus provides a reliable and facilitative model of aerosol-transmitted, orthopoxviral respiratory disease.

Administration, Inhalation↗
PubMed1999

Pulmonary distribution of aerosolized technetium Tc 99m pentetate after administration of a single dose of aerosolized albuterol sulfate in horses with recurrent airway obstruction.

OBJECTIVE: To determine whether pulmonary distribution of aerosolized technetium Tc 99m pentetate is improved after inhalation of a single dose of albuterol sulfate in horses susceptible to recurrent airway obstruction (heaves). ANIMALS: 6 horses with heaves and 4 horses with normal respiratory tract function. PROCEDURE: Images were obtained during ventilation of horses at baseline (maximal change in pleural pressure during tidal breathing [deltaPpImax] >15 cm H2O) and after aerosolized albuterol sulfate (360 microg) administration, with a 24-hour washout period between experiments. The deltaPpImax was determined prior to the baseline scan, prior to albuterol sulfate administration, and 5 minutes after albuterol sulfate administration. Images were assessed by visual inspection (semi-quantitative scoring system) and histogram analysis. RESULTS: Images obtained from horses with heaves had nonuniform pulmonary distribution of radionuclide characterized by poor penetration in peripheral lung fields and excess deposition in large airways. Histogram analysis of images of the caudal portions of the lungs revealed nonuniform radionuclide deposition in horses with heaves and uniform radionuclide deposition in control horses. CONCLUSION: Administration of a single dose of aerosolized albuterol sulfate improved pulmonary distribution of aerosolized radiolabeled pentetate suspension in horses with heaves but did not alter pulmonary distribution in clinically normal horses. CLINICAL RELEVANCE: Precedent bronchodilator administration may improve pulmonary distribution of aerosolized, surface-active anti-inflammatory preparations.

Administration, Inhalation↗
PubMed2000

Light scattering characteristics of aerosols as a function of relative humidity: Part I--A comparison of measured scattering and aerosol concentrations using the theoretical models.

The Southeastern Aerosol and Visibility Study (SEAVS) was undertaken to characterize the size-dependent composition, thermodynamic properties, and optical characteristics of the ambient atmospheric particles in the southeastern United States. The field portion of the study was carried out from July 15 to August 25, 1995. As part of the study a relative humidity controlled inlet was built to raise or lower the relative humidity to predetermined levels before the aerosol was passed into an integrating nephelometer or particle-sizing device. Five other integrating nephelometers were operated in various configurations, two of which were fitted with a 2.5 microns inlet. Fine particle (< 2.5 microns) samplers were operated to measure concentrations of sulfate, nitrate, and ammonium ions, organic and elemental carbon, and fine soil. Mass size distributions were measured with an eight-stage, single orifice cascade impactor. Four different strategies for estimating scattering were used. First, an externally mixed model with constant specific scattering coefficients, sulfate ion mass interpreted as ammonium bisulfate, and ammonium bisulfate growth as a function of relative humidity, is assumed. Second, an externally mixed aerosol model, assuming constant dry specific scattering but with sulfate ammoniation and associated composition-dependent hygroscopicity explicitly accounted for, is used. Third, an externally mixed aerosol model, but with sulfate ammoniation, associated growth as a function of relative humidity, and sulfate size distributions, is applied. Fourth, an internally mixed aerosol model with measured sulfur size distributions and estimated size distributions for other species is used with the growth characteristics of the mixture being estimated using the Zdanovskii-Stokes-Robinson (ZSR) assumptions. Only ionic species were considered to be hygroscopic. The second, third, and fourth approaches yield similar results with reconstructed scattering comparing quite favorably with measured scattering. Accounting for sulfate ammoniation and associated water uptake was the most important detail in achieving closure between measurements and modeled scattering. In general, differences between estimated scattering, assuming internally or externally mixed models, was small. These same models were used to estimate wet to dry scattering ratios. The R2 for an ordinary least-squares regression between measured and predicted ratios was high (0.71-0.92), and in most cases the scattering ratio was insensitive to modeling assumptions. However, during some sample periods differences between predicted scattering ratios for the different modeling assumptions were as high as 30%.

Aerosols↗
PubMed1976

[Effect of the site of microbial aerosol application on the pathogenesis and clinical picture of aerosol infection].

On the basis of experimental and clinical study of infections with the aerosol mechanism of infection there was revealed a relationship between the fractional-dispersive composition of the microbial aerosol, the porta of infection and the clinico-pathogenetic peculiarities of the course of the disease. On the example of tularemia, plague and other nosological forms it was demonstrated that coarse-dispersive aerosol caused development of oculo-bubonic and anginous-bubonic form of the disease, whereas the high-dispersive aerosol led to the appearance of primary pneumonia. In experimental aerosol infection with the causative agents in which the infection under natural conditions is not air-borne (botulism, American horse encephalo-myelitis, etc.) specific disease as a rule develops without any primary affection of the respiratory organs.

Adenoviridae Infections↗
PubMed2004

Aerosol lidar intercomparison in the framework of the EARLINET project. 3. Raman lidar algorithm for aerosol extinction, backscatter, and lidar ratio.

An intercomparison of the algorithms used to retrieve aerosol extinction and backscatter starting from Raman lidar signals has been performed by 11 groups of lidar scientists involved in the European Aerosol Research Lidar Network (EARLINET). This intercomparison is part of an extended quality assurance program performed on aerosol lidars in the EARLINET. Lidar instruments and aerosol backscatter algorithms were tested separately. The Raman lidar algorithms were tested by use of synthetic lidar data, simulated at 355, 532, 386, and 607 nm, with realistic experimental and atmospheric conditions taken into account. The intercomparison demonstrates that the data-handling procedures used by all the lidar groups provide satisfactory results. Extinction profiles show mean deviations from the correct solution within 10% in the planetary boundary layer (PBL), and backscatter profiles, retrieved by use of algorithms based on the combined Raman elastic-backscatter lidar technique, show mean deviations from solutions within 20% up to 2 km. The intercomparison was also carried out for the lidar ratio and produced profiles that show a mean deviation from the solution within 20% in the PBL. The mean value of this parameter was also calculated within a lofted aerosol layer at higher altitudes that is representative of typical layers related to special events such as Saharan dust outbreaks, forest fires, and volcanic eruptions. Here deviations were within 15%.

Journal Article↗
PubMed2006

Ground-truth aerosol lidar observations: can the Klett solutions obtained from ground and space be equal for the same aerosol case?

Upcoming multiyear satellite lidar aerosol observations need strong support by a worldwide ground-truth lidar network. In this context the question arises as to whether the ground stations can deliver the same results as obtained from space when the Klett formalism is applied to elastic backscatter lidar data for the same aerosol case. This question is investigated based on simulations of observed cases of simple and complex aerosol layering. The results show that the differences between spaceborne and ground-based observations can be as large as 20% for the backscatter and extinction coefficients and the optimum estimates of the column lidar ratios. In cases with complex aerosol layering, the application of the two-layer approach can lead to similar results (space, ground) and accurate products provided that horizontally homogeneous aerosol conditions are given.

Journal Article↗
PubMed1984

Respiratory responses of humans exposed to an aerosol-gas pollutant mixture: multivariate contrast of a complex atmosphere to clean air and sodium chloride aerosol controls.

Data from a group of 20 subjects with normal baseline pulmonary function, who were exposed for 2 h to a test atmosphere containing a complex mixture of pollutants, have been contrasted with data from two other groups exposed to presumably non-toxic control atmospheres. Group 1 was exposed to clean air, group 2 was exposed to clean air containing sodium chloride aerosol at 270 micrograms m-3, and group 3 was exposed to the complex atmosphere containing sodium chloride (332 micrograms m-3) and zinc ammonium sulfate (23 micrograms m-3) aerosols plus nitrogen dioxide (0.5 ppm) and sulfur dioxide (0.5 ppm). These atmospheres (ranked according to the presumed relative toxicities of the components; clean air = 0, sodium chloride = 1, complex mixture = 2) were contrasted using multiple regression and partial correlation analyses. The effects of exposure to the complex gas-aerosol mixture on forced expiratory performance were not significantly different from those observed in subjects exposed to clean air or to sodium chloride aerosol.

Adolescent↗
PubMed1985

Drug absorption from inhalation aerosols administered by positive-pressure ventilation. II: Effect of disodium fluorescein aerosol particle size on fluorescein absorption kinetics in the beagle dog respiratory tract.

Solid, polydispersed disodium fluorescein aerosols (MMDae = 1.1, 3.5, and 4.4 micron) were administered under the same respiratory regime, direct to the respiratory tracts of two beagle dogs by positive-pressure ventilation. Subsequent to aerosol administration, plasma fluorescein concentrations were determined after sampling from an indwelling cannula. The amount absorbed as a function of time was estimated from these and additional data collected from intravenous control experiments in the same animals. Fluorescein absorption from the respiratory tract was apparently a first-order process, the rate increasing directly with the bioavailable dose. First-order rate constants differed but appeared unrelated to aerosol particle size, possibly reflecting similarities in their regional deposition in the canine lung. The average value for the absorption half-lives in the dogs were 19.3 and 12.2 min, showing that even lipophobic solutes such as the fluorescein dianion, are absorbed extremely rapidly via the lung. In one dog, the rate constant for fluorescein absorption after intratracheal instillation of a solution of the disodium salt was within the range of those following aerosol administration. Possible explanations are discussed.

Absorption↗