Les pneumopathies acquises sous ventilation mécanique (PAVM) sont responsables d'une mortalité élevée. La nébulisation d'antibiotiques permet d'améliorer l'efficacité de leur traitement. Pour autant, aucune donnée pharmacocinétique portant sur la colistine et la gentamicine ne permet de recommander un schéma posologique particulier.Nous avons comparé les propriétés pharmacocinétiques plasmatique et intra-pulmonaire de la colistine (administrée sous forme de prodrogue, le colistiméthate sodique ou CMS) et de la gentamicine selon le mode d'administration (nébulisation ou perfusion intraveineuse) chez des patients de réanimation présentant une PAVM.Les concentrations intra-pulmonaires de colistine et de gentamicine étaient, respectivement, de 10 à 40 et 50 à 70 fois supérieures, après nébulisation, à celles retrouvées après administration d'une même dose par voie intraveineuse. La nébulisation permettrait également de limiter le risque de toxicité systémique avec une biodisponibilité inférieure à 10%.En assurant de fortes concentrations intra-pulmonaires et un faible passage systémique, la nébulisation de CMS et de gentamicine pourrait être une bonne alternative à leur administration intraveineuse dans le traitement des PAVM. / Ventilator-associated pneumonia (VAP) is associated with high mortality. Nebulization of antibiotics improves outcome of patient with VAP. However, pharmacokinetic data concerning colistin and gentamicin allowing for optimal dosing regimen recommendation are lacking.We compared systemic and pulmonary concentrations of colistin (administered as an inactive prodrug, colistin methanesulfonate or CMS) and gentamicin according to the route of administration (nebulization and intravenous infusion) in critically ill patients with VAP.Intra-pulmonary concentrations of colistin and gentamicin were 10 to 40-fold and 50 to 70-fold much higher after nebulization than after the same dose by intravenous route, respectively. Nebulization has also the theoretical potential advantage to improve patients' safety in relation to the colistin biodisponibility lower than 10%.With high intra-pulmonary concentrations and very low systemic absorption, CMS and gentamicin nebulization may be good alternatives to intravenous infusion for VAP treatment.

The use of slotted quartz tube (SQT) as an atom trap in atomic absorption spectrometry (AAS) provides a more stable chemical environment for atomization / the technique is simple and easily applicable in any laboratory. This thesis study involves application of SQT together with some other approaches to thallium determination by AAS. The first stages involve the efforts to improve nebulization efficiency of conventional flame atomic absorption spectrometry (FAAS) with and without the use of SQT. This is achieved by mixing 100 &micro / L of propanol with 500 &micro / L of Tl standard solution using the optimum conditions. By this method, Propanol-SQT-FAAS, 4.49 times enhancement in sensitivity has been obtained with respect to conventional FAAS, method in which the characteristic concentration was calculated as 894 ng/mL. The second stage of investigation is about the use of SQT as an atom trap, AT, preconcentration device for thallium determination. The similar technique has been successfully applied to some other analytes such as Pb, Cd, Bi and Au / detection limits at the level of ng/mL were obtained in the previous studies. In the present work, the analyte atoms are trapped on the inner surface of SQT in the presence of a lean air-acetylene flame for few minutes. After this collection step, a volume of methyl isobutyl ketone, MIBK, amounting to 10-50 microliters is introduced via conventional nebulization / this causes a momentary alteration in the flame composition and thus results in the release of trapped analyte atoms from the quartz surface. This revolatilization step is followed by a rapid atomization and transient signal was obtained. In addition to this method, a novel approach has been investigated where the inner surface of SQT was modified by using a metal coating with low volatility. For this purpose, eight different coating materials which were tungsten, palladium, molybdenum, gold, tantalum, zirconium, titanium and osmium, have been applied to the inner surface of SQT and as osmium was found to be most appropriate one, the rest of the study was continued with Os-Coated-SQT. This modification provided a better surface than quartz alone so that analyte atoms are trapped more efficiently and also released easily. Although the working principle of the Coated-SQT-AT-FAAS method is same with SQT-AT-FAAS, the conditions for SQT-AT-FAAS and Os-Coated-SQT-AT-FAAS methods were optimized seperately. Limit of detections, 3s/m, has been found to be 38 ng/mL and 3.5 ng/mL for these cases, respectively. While the SQT-AT-FAAS method has provided 92 fold enhancement, the Os-Coated-SQT-AT-FAAS method has provided a 319 fold sensitivity improvement with respect to conventional FAAS method.

Dans ce travail de thèse, l'efficacité de la voie intrapulmonaire et les paramètres biopharmaceutiques influençant la diffusion pulmonaire après nébulisation d'antibiotiques ont été évalués. La présence et l'impact de certaines pompes d'efflux dans un modèle in vitro de cellules primaires épithéliales pulmonaires de rat ont été testés. Trois fluoroquinolones et la colistine ont été utilisées comme molécules de référence. La combinaison des molécules testées a permis d'obtenir une vue d'ensemble des caractéristiques de diffusion intrapulmonaire des antibiotiques. L'étude in vivo avec les fluoroquinolones a démontré que les concentrations pulmonaires de ces molécules sont plus importantes que dans le plasma, probablement dû à la présence des transporteurs comme la glycoprotéine-P. La présence de ces transporteurs a été confirmée dans le modèle de cellules pulmonaires de rats. L'étude in vivo avec la colistine a montré qu'une lente diffusion pourrait conférer un avantage à la nébulisation par rapport à l'administration intraveineuse. En conclusion, l'administration par nébulisation des molécules, qui traversent les tissus lentement (colistine), pourrait être avantageuse, alors que pour d'autres, qui traversent vite la barrière (fluoroquinolones), la voie nébulisée pourrait ne pas présenter des avantages par rapport à la voie intraveineuse. De plus, les résultats ont démontré qu'une faible perméabilité à travers le poumon (colistine) pourrait donner un avantage à la nébulisation des antibiotiques, tandis qu'une affinité pour des transporteurs (fluoroquinolones) semble présenter un intérêt aussi bien dans le cadre d'une nébulisation que d'une administration intraveineuse. / The aim of this study was to investigate the efficiency of intrapulmonary administration and the biopharmaceutical parameters regulating the pulmonary diffusion following nebulization. We examined whether certain efflux pumps were present in an in vitro model of rat lung cells and whether these efflux pumps could be beneficial by increasing lung concentrations in vivo. Fluoroquinolones and colistin were the molecules used as reference. These different molecules allowed an overview of the intrapulmonary diffusion characteristics of antibiotics. The in vivo study with fluoroquinolones showed that their lung concentrations are higher than in plasma, probably due to glycoprotein-P. The presence of this efflux pump was confirmed in the model with rat lung cells. The in vivo study with colistin showed that a slow diffusion may confer an advantage for nebulization over intravenous administration. In conclusion, the nebulization molecules passing slowly (colistin) across the tissues may be advantageous, whereas for others, with a fast passage across the barrier (fluoroquinolones), the pulmonary route may not provide an advantage over the intravenous administration. Moreover, the results showed that a slow permeability across the lung (colistin) may confer an advantage for the antibiotic nebulization, while affinity by transporters (fluoroquinolones) is beneficial for both nebulization and intravenous administration.

<p>Although, pulmonary drug delivery is a well established means for targeting of drugs to the lungs for the treatment of respiratory diseases as well as for the systemic delivery of volatile anesthetic agents, drug absorption kinetics in the lung have not been subjected to extensive research. The main objective of this thesis was to investigate drug absorption characteristics of the lung barrier, using the isolated and perfused rat lung model and in vivo pharmacokinetic studies in rats. Physicochemically diverse drugs (i.e. atenolol, budesonide, cromolyn, cyanocobalamin, enalapril, enalaprilate, formoterol, imipramine, losartan, metoprolol, propranolol, talinolol, terbutaline, and the tetrapeptide TArPP) were used as model compounds. In connection to these investigations, a nebulization catheter device was successfully adapted and evaluated as a new technique for delivery of defined aerosol doses to the rat lung. In addition, a physicochemical profile of the inhaled drugs on the market worldwide during 2001 was made.</p><p>The pulmonary first-order absorption rate constant and bioavailability were found to correlate to the drug lipophilicity, the molecular polar surface area, and the apparent permeability of Caco-2 cell monolayers. In contrast to the intestinal mucosa and the blood-brain barrier, the pulmonary epithelium was highly permeable to drugs with a high molecular polar surface area. Accordingly, a small hydrophilic tetrapeptide (oral bioavailability ~0.5%) showed a complete bioavailability after pulmonary delivery to rats in vivo. Regional differences in bioavailability, absorption rate, and first-pass metabolism of the peptide was demonstrated after targeted delivery to different regions of the respiratory tract in rats in vivo. The high pulmonary bioavailability of the efflux transporter substrates losartan and talinolol provides functional evidence for an insignificant role of efflux transporters such as P-glycoprotein in limiting the absorption of these drugs from the rat lung. </p><p>The results of this thesis demonstrate that the lung efficiently absorbs drugs with a wide range of lipophilicity. The pulmonary route should thus be regarded as a potential alternative for administration of drugs with low oral bioavailability. In addition, drug inhalation present an opportunity to attain a more rapid onset of drug action than can be attained by the oral route.</p>

Although, pulmonary drug delivery is a well established means for targeting of drugs to the lungs for the treatment of respiratory diseases as well as for the systemic delivery of volatile anesthetic agents, drug absorption kinetics in the lung have not been subjected to extensive research. The main objective of this thesis was to investigate drug absorption characteristics of the lung barrier, using the isolated and perfused rat lung model and in vivo pharmacokinetic studies in rats. Physicochemically diverse drugs (i.e. atenolol, budesonide, cromolyn, cyanocobalamin, enalapril, enalaprilate, formoterol, imipramine, losartan, metoprolol, propranolol, talinolol, terbutaline, and the tetrapeptide TArPP) were used as model compounds. In connection to these investigations, a nebulization catheter device was successfully adapted and evaluated as a new technique for delivery of defined aerosol doses to the rat lung. In addition, a physicochemical profile of the inhaled drugs on the market worldwide during 2001 was made. The pulmonary first-order absorption rate constant and bioavailability were found to correlate to the drug lipophilicity, the molecular polar surface area, and the apparent permeability of Caco-2 cell monolayers. In contrast to the intestinal mucosa and the blood-brain barrier, the pulmonary epithelium was highly permeable to drugs with a high molecular polar surface area. Accordingly, a small hydrophilic tetrapeptide (oral bioavailability ~0.5%) showed a complete bioavailability after pulmonary delivery to rats in vivo. Regional differences in bioavailability, absorption rate, and first-pass metabolism of the peptide was demonstrated after targeted delivery to different regions of the respiratory tract in rats in vivo. The high pulmonary bioavailability of the efflux transporter substrates losartan and talinolol provides functional evidence for an insignificant role of efflux transporters such as P-glycoprotein in limiting the absorption of these drugs from the rat lung. The results of this thesis demonstrate that the lung efficiently absorbs drugs with a wide range of lipophilicity. The pulmonary route should thus be regarded as a potential alternative for administration of drugs with low oral bioavailability. In addition, drug inhalation present an opportunity to attain a more rapid onset of drug action than can be attained by the oral route.

Cancer is the second leading cause of death in the United States and its onset is highly incident in the lungs, with very low long-term survival rates. Chemotherapy plays a significant role for lung cancer treatment, and pulmonary delivery may be a potential route for anticancer drug delivery to treat lung tumors. Coenzyme Q₁₀ (CoQ₁₀) is a poorly-water soluble compound that is being investigated for the treatment of carcinomas. In this work, we hypothesize that formulations of CoQ10 may be developed for pulmonary delivery with a satisfactory pharmacokinetic profile that will have the potential to improve a pharmacodynamic response when treating lung malignancies. The formulation design was to use a vibrating-mesh nebulizer to aerosolize aqueous dispersions of CoQ₁₀ stabilized by phospholipids physiologically found in the lungs. In the first study, a method was developed to measure the surface tension of liquids, a physicochemical property that has been shown to influence the aerosol output characteristics from vibrating-mesh nebulizers. Subsequently, this method was used, together with analysis of particle size distribution, zeta potential, and rheology, to further evaluate the factors influencing the capability of this nebulizer system to continuously and steadily aerosolize formulations of CoQ₁₀ prepared with high pressure homogenization. The aerosolization profile (nebulization performance and in vitro drug deposition of nebulized droplets) of formulations prepared with soybean lecithin, dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC) were evaluated. The rheological behavior of these dispersions was found to be the factor that may be indicative of the aerosolization output profile. Finally, the pulmonary deposition and systemic distribution of CoQ₁₀ prepared as DMPC, DPPC, and DSPC dispersions were investigated in vivo in mice. It was found that high drug amounts were deposited and retained in the mouse lungs for at least 48 hours post nebulization. Systemic distribution was not observed and deposition in the nasal cavity occurred at a lower scale than in the lungs. This body of work provides evidence that CoQ₁₀ may be successfully formulated as dispersions to be aerosolized using vibrating-mesh nebulizers and achieve high drug deposition in the lungs during inhalation. / text

Cancer is the second leading cause of death in the United States and its onset is highly incident in the lungs, with very low long-term survival rates. Chemotherapy plays a significant role for lung cancer treatment, and pulmonary delivery may be a potential route for anticancer drug delivery to treat lung tumors. Coenzyme Q₁₀ (CoQ₁₀) is a poorly-water soluble compound that is being investigated for the treatment of carcinomas. In this work, we hypothesize that formulations of CoQ10 may be developed for pulmonary delivery with a satisfactory pharmacokinetic profile that will have the potential to improve a pharmacodynamic response when treating lung malignancies. The formulation design was to use a vibrating-mesh nebulizer to aerosolize aqueous dispersions of CoQ₁₀ stabilized by phospholipids physiologically found in the lungs. In the first study, a method was developed to measure the surface tension of liquids, a physicochemical property that has been shown to influence the aerosol output characteristics from vibrating-mesh nebulizers. Subsequently, this method was used, together with analysis of particle size distribution, zeta potential, and rheology, to further evaluate the factors influencing the capability of this nebulizer system to continuously and steadily aerosolize formulations of CoQ₁₀ prepared with high pressure homogenization. The aerosolization profile (nebulization performance and in vitro drug deposition of nebulized droplets) of formulations prepared with soybean lecithin, dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC) were evaluated. The rheological behavior of these dispersions was found to be the factor that may be indicative of the aerosolization output profile. Finally, the pulmonary deposition and systemic distribution of CoQ₁₀ prepared as DMPC, DPPC, and DSPC dispersions were investigated in vivo in mice. It was found that high drug amounts were deposited and retained in the mouse lungs for at least 48 hours post nebulization. Systemic distribution was not observed and deposition in the nasal cavity occurred at a lower scale than in the lungs. This body of work provides evidence that CoQ₁₀ may be successfully formulated as dispersions to be aerosolized using vibrating-mesh nebulizers and achieve high drug deposition in the lungs during inhalation.

In analytical chemistry the main goal is normally to determine the identity and/or concentration of one or more species in a sample. The samples analyzed are often natural samples, containing numerous different species in a complex matrix and the choice of technique for multi-elemental detection is in general inductively coupled plasma spectrometry. The chemical forms of an element can affect many of its characteristics e.g. toxicity, which makes speciation analysis important. Therefore, determination of the identity and quantity of an element is still important, but for many applications measurements of total element concentration provides insufficient information. To be able to perform speciation analysis, separation, identification and/or characterization of the various forms of elements in the sample has to be accomplished. Speciation analysis has been employed in a wide range of disciplines, including for example environmental science, biology and clinical chemistry. This thesis describes work to improve and understand the elemental speciation analysis with liquid chromatography coupled to plasma spectrometry and also highlights the importance and potential of the synergy between atomic spectrometry and molecular mass spectrometry. The combination of the matrix tolerant, robust and very sensitive plasma spectrometry used together with molecular mass spectrometry, which provides structural information and the possibility to identify unknown species, is demonstrated to be a very powerful tool for speciation analysis. In this thesis methods are developed for on-line sample clean-up and pre-concentration coupled to liquid chromatography and plasma spectrometry, which makes handling of small sample volumes easier and also decreases the risk of contamination. The problems associated with organic modifiers in plasma spectrometry are also addressed. Applications of speciation analysis are exemplified by analysis of aluminium-chelated siderophores in field-soil solutions and organic phosphorous species in aquatic sediments. The possibility to analyze un-dissolved samples as slurries with minimal sample preparation is also discussed.