La pipéracilline-tazobactam est une combinaison d’un antibiotique bêta-lactamine et d’un inhibiteur des bêta-lactamases fréquemment prescrite aux soins intensifs. Les patients admis aux soins intensifs présentent souvent une réponse très variable au traitement en raison des multiples changements pathophysiologiques présents dans cette population qui modifient le profil pharmacocinétique du médicament. La modélisation pharmacocinétique de population est une approche qui permet d’expliquer une partie de cette variabilité au moyen d’équations mathématiques. À l’aide d’un modèle pharmacocinétique, il est possible de décrire le devenir systémique du médicament à l’aide de paramètres clés comme la clairance et le volume de distribution. Également, ce type de modèle offre la possibilité d’effectuer des simulations de régimes posologiques pour faciliter l’atteinte des cibles thérapeutiques, dans une optique d’individualisation de la pharmacothérapie. Ce projet de maîtrise avait trois objectifs. Le premier était de documenter la variabilité associée à la pharmacocinétique de la pipéracilline-tazobactam aux soins intensifs en réalisant une revue de la littérature. Cette revue a pu relever certaines covariables significatives dans les modèles qui expliquaient une partie de la variabilité observée, comme la clairance de la créatinine et le poids. Le second avait pour but d’évaluer la performance prédictive des modèles pharmacocinétiques déjà disponibles dans la littérature pour la pipéracilline-tazobactam à l’aide d’une base de données indépendante. Parmi les modèles évalués, le meilleur a été retenu afin d’optimiser les régimes posologiques aux soins intensifs. Ainsi, grâce à ce modèle, un nomogramme prenant en considération la fonction rénale du patient a été développé pour faciliter l’atteinte des cibles thérapeutiques lors de l’administration de la pipéracilline-tazobactam. Finalement, le troisième objectif était d’évaluer l’impact d’une variation de la fraction libre de la pipéracilline-tazobactam sur la performance prédictive du modèle ainsi que son impact sur la pharmacocinétique du médicament. Cette évaluation a fait ressortir l’importance d’utiliser la concentration libre plutôt que d’utiliser la concentration totale de la pipéracilline-tazobactam pour le suivi thérapeutique, car l’assomption d’une fraction libre théorique unique pour tous les patients peut nuire à la prédiction adéquate des concentrations par un modèle pharmacocinétique en milieu clinique. / Piperacillin-tazobactam is a beta-lactam/beta-lactamase inhibitor antibiotic combination frequently prescribed in intensive care units. Admitted patients often show a large variability in treatment response due to multiple pathophysiological changes that alter the pharmacokinetic profile of the drug. Population pharmacokinetic modeling is an approach that can explain some of this variability using mathematical equations. Using a pharmacokinetic model, key parameters such as clearance and volume of distribution can be retrieved to describe the systemic exposure of the drug. Also, this type of model offers the possibility to perform simulations to find optimized dosing regimens that may facilitate the achievement of target concentrations to individualize drug therapy. This master's project had three objectives. The first was to document the variability in the pharmacokinetics of piperacillin-tazobactam in the intensive care unit by conducting a literature review. This review was able to highlight key covariates, such as creatinine clearance and body weight, that could explain the variability observed in this population. The second was to evaluate the predictive performance of pharmacokinetic models available in the literature for piperacillin-tazobactam using an independent database. Among the models evaluated, the best one was selected to offer optimized dosing regimens for critically ill patients. Thus, with this model, a nomogram that accounts for the patient's renal function was developed to facilitate the achievement of therapeutic targets of piperacillin-tazobactam. Finally, the third objective was to evaluate the impact of fluctuations in the unbound fraction of piperacillin-tazobactam on the predictive performance of the model as well as its impact on the pharmacokinetics of the drug. This evaluation highlighted the importance of using unbound piperacillin concentrations for drug monitoring over total concentrations, as applying a theoretical unbound fraction to every individual may hinder the predictive performance of pharmacokinetic model if it is used in a clinical setting.

Le méthotrexate (MTX), un agent anti-cancéreux fréquemment utilisé en chimiothérapie, requiert généralement un suivi thérapeutique de la médication (Therapeutic Drug Monitoring, TDM) pour surveiller son niveau sanguin chez le patient afin de maximiser son efficacité tout en limitant ses effets secondaires. Malgré la fenêtre thérapeutique étroite entre l’efficacité et la toxicité, le MTX reste, à ce jour, un des agents anti-cancéreux les plus utilisés au monde. Les techniques analytiques existantes pour le TDM du MTX sont coûteuses, requièrent temps et efforts, sans nécessairement fournir promptement les résultats dans le délai requis. Afin d’accélérer le processus de dosage du MTX en TDM, une stratégie a été proposée basée sur un essai compétitif caractérisé principalement par le couplage plasmonique d’une surface métallique et de nanoparticules d’or. Plus précisément, l’essai quantitatif exploite la réaction de compétition entre le MTX et une nanoparticule d’or fonctionnalisée avec l’acide folique (FA-AuNP) ayant une affinité pour un récepteur moléculaire, la réductase humaine de dihydrofolate (hDHFR), une enzyme associée aux maladies prolifératives. Le MTX libre mixé avec les FA-AuNP, entre en compétition pour les sites de liaison de hDHFR immobilisés sur une surface active en SPR ou libres en solution. Par la suite, les FA-AuNP liées au hDHFR fournissent une amplification du signal qui est inversement proportionnelle à la concentration de MTX. La résonance des plasmons de surface (SPR) est généralement utilisée comme une technique spectroscopique pour l’interrogation des interactions biomoléculaires. Les instruments SPR commerciaux sont généralement retrouvés dans les grands laboratoires d’analyse. Ils sont également encombrants, coûteux et manquent de sélectivité dans les analyses en matrice complexe. De plus, ceux-ci n’ont pas encore démontré de l’adaptabilité en milieu clinique. Par ailleurs, les analyses SPR des petites molécules comme les médicaments n’ont pas été explorés de manière intensive dû au défi posé par le manque de la sensibilité de la technique pour cette classe de molécules. Les développements récents en science des matériaux et chimie de surfaces exploitant l’intégration des nanoparticules d’or pour l’amplification de la réponse SPR et la chimie de surface peptidique ont démontré le potentiel de franchir les limites posées par le manque de sensibilité et l’adsorption non-spécifique pour les analyses directes dans les milieux biologiques. Ces nouveaux concepts de la technologie SPR seront incorporés à un système SPR miniaturisé et compact pour exécuter des analyses rapides, fiables et sensibles pour le suivi du niveau du MTX dans le sérum de patients durant les traitements de chimiothérapie. L’objectif de cette thèse est d’explorer différentes stratégies pour améliorer l’analyse des médicaments dans les milieux complexes par les biocapteurs SPR et de mettre en perspective le potentiel des biocapteurs SPR comme un outil utile pour le TDM dans le laboratoire clinique ou au chevet du patient. Pour atteindre ces objectifs, un essai compétitif colorimétrique basé sur la résonance des plasmons de surface localisée (LSPR) pour le MTX fut établi avec des nanoparticules d’or marquées avec du FA. Ensuite, cet essai compétitif colorimétrique en solution fut adapté à une plateforme SPR. Pour les deux essais développés, la sensibilité, sélectivité, limite de détection, l’optimisation de la gamme dynamique et l’analyse du MTX dans les milieux complexes ont été inspectés. De plus, le prototype de la plateforme SPR miniaturisée fut validé par sa performance équivalente aux systèmes SPR existants ainsi que son utilité pour analyser les échantillons cliniques des patients sous chimiothérapie du MTX. Les concentrations de MTX obtenues par le prototype furent comparées avec des techniques standards, soit un essai immunologique basé sur la polarisation en fluorescence (FPIA) et la chromatographie liquide couplée avec de la spectrométrie de masse en tandem (LC-MS/MS) pour valider l’utilité du prototype comme un outil clinique pour les tests rapides de quantification du MTX. En dernier lieu, le déploiement du prototype à un laboratoire de biochimie dans un hôpital démontre l’énorme potentiel des biocapteurs SPR pour utilisation en milieux clinique. / Methotrexate (MTX) cancer therapy requires therapeutic drug monitoring (TDM) for following its levels in a patient during the course of treatment in order to maximize efficacy while minimizing side effects. Despite its narrow therapeutic window, MTX remains until this date, one of the most employed chemotherapy agents. Existing TDM analytical techniques for MTX are costly, time-consuming and labor intensive which are not suitable to promptly generate results within the therapy timeframe. To provide rapid MTX quantification for TDM, a strategy is proposed based on a competitive assay featuring gold nanoparticles and surface plasmonic coupling. More specifically, the inhibition of MTX with its molecular receptor, human dihydrofolate reductase (hDHFR), an enzyme associated with proliferative diseases, is explored. Free MTX mixed with folic acid-functionalized gold nanoparticles (FA-AuNP) are in competition for hDHFR binding sites immobilized on a SPR active surface or free in solution. FA-AuNP binding to hDHFR provides signal amplification which is inversely proportional to the concentration of MTX. Surface plasmon resonance (SPR) is commonly used as a spectroscopic technique for the interrogation of biomolecular interactions. Current commercial SPR instruments are laboratory-based, bulky, expensive, lack sensitivity in complex matrix and have not shown adaptability in clinical settings. In addition, SPR analysis of small molecules such as drugs has not been extensively explored due to lack of sensitivity. The recent advances in materials science and surface chemistry exploiting gold nanoparticle integration for SPR response enhancement and peptide surface chemistry have shown potential in overcoming the poor sensitivity and surface-fouling limitations for crude biofluids analysis. These novel concepts of SPR technology are incorporated with a miniaturized fully integrated SPR prototype to conduct fast, reliable and sensitive analysis to monitor MTX levels of a patient undergoing chemotherapy. The objective of the thesis is to explore different strategies in improving drug analysis in a complex matrix using SPR biosensors and to put in perspective of the potential of SPR biosensors as a useful TDM tool in clinical laboratories or at a point-of-care situation. To achieve these objectives, a colorimetric solution-based MTX competitive assay is first established with FA-AuNP. Then, the solution-based MTX competitive assay is translated onto a SPR platform. For both developed assays, sensitivity, selectivity, detection limit, dynamic range optimization as well as analysis of methotrexate in complex matrix are inspected. Furthermore, the SPR prototype is validated by its equivalent performance to existing SPR systems and by its utility in executing MTX analysis in actual serum samples from patients undergoing chemotherapy. The concentrations of MTX obtained by SPR biosensing are compared to standard techniques: fluorescence polarization immunoassay (FPIA) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in order to confirm the feasibility of SPR biosensors as a useful clinical tool for performing rapid MTX concentration evaluation. Finally, the successful deployment of the prototype to a hospital laboratory demonstrates enormous prospective of SPR biosensors in clinical use.

A esquizofrenia é um transtorno neuropsiquiátrico crônico que afeta aproximadamente 1% da população mundial. As teorias neurobiológicas descrevem que a esquizofrenia é essencialmente causada por alterações bioquímicas e estruturais do cérebro, devido às disfunções nos sistemas glutamatérgico, dopaminérgico e serotoninérgico. Desta forma, a determinação das concentrações de aminoácidos e neurotransmissores em amostras de plasma de pacientes esquizofrênicos pode auxiliar na avaliação da eficácia da terapia. Além dos antipsicóticos, medicação de primeira linha no tratamento inicial da esquizofrenia, a maioria dos pacientes também faz uso concomitante de outras classes de fármacos, tais como antidepressivos, anticonvulsivantes e ansiolíticos para minimizar os sintomas associados a esta doença. Nesta tese, um método empregando a precipitação de proteínas (PPT) e a cromatografia líquida por interação hidrofílica acoplada à espectrometria de massas em tandem (HILIC-MS/MS) foi adequadamente desenvolvido e validado para a determinação de aminoácidos (aspartato, serina, glicina, alanina, metionina, leucina, tirosina e triptofano) e neurotransmissores (glutamato e ácido -aminobutírico) em amostras de plasma de 35 pacientes esquizofrênicos em tratamento com clozapina (27 pacientes) e olanzapina (8 pacientes) para avaliar a eficácia do tratamento, tendo como controle 38 voluntários sadios. O método HILIC-MS/MS apresentou linearidade do LIQ (9,7 pmol mL-1 - 13,3 nmol mL-1) ao LSQ (19,4 nmol mL-1 - 800 nmol mL-1), tempo de análise de 3,0 min, exatidão com EPR de -18 a 19% e precisão com CV de 0,1 a 16% (LIQ). A análise de variância (ANOVA), seguida por teste post-hoc de Duncan, revelou que os níveis médios plasmáticos (nmol mL-1) de metionina (F2,70 = 3,14, p = 0,049) de pacientes esquizofrênicos em tratamento com olanzapina foram significativamente mais elevados, quando comparados aos valores obtidos com o grupo controle (voluntários saudáveis), já o nível de glutamato em pacientes esquizofrênicos em tratamento com clozapina apresentaram tendência a valores mais altos (F2.70 = 2,50, p = 0,090). Já os métodos, PPT/LC-MS/MS e LC-MS/MS no modo column switching utilizando uma coluna monolítica de sílica híbrida com grupos cianopropil na primeira dimensão, foram desenvolvidos e validados para a determinação dos antipsicóticos (olanzapina, quetiapina, clozapina, haloperidol e clorpromazina), antidepressivos (mirtazapina, paroxetina, citalopram, sertralina, imipramina, clomipramina e fluoxetina), anticonvulsivantes (carbamazepina e lamotrigina), e ansiolíticos (diazepam e clonazepam) em amostras de plasma de pacientes esquizofrênicos para fins de monitorização terapêutica. O método PPT/LC-MS/MS apresentou linearidade do LIQ (0,2 ng mL-1 - 5,0 ng mL-1) ao LSQ (40,5 ng mL-1 - 10,5 g mL-1), exatidão com EPR de -9,7 a 8,0%, e precisão com CV de 0,1 a 12%. Já o método LC-MS/MS no modo column switching apresentou linearidade do LIQ (63,0 pg mL-1 - 1250,0 pg mL-1) ao LSQ (40,5 ng mL-1 - 10,5 g mL-1), exatidão com EPR de -14 a 12% e precisão com CV de 0,6 a 6,5%. A pré-concentração seletiva dos fármacos na coluna monolítica com grupos cianopropil incorporados e a remoção dos componentes endógenos da amostra biológica, antes da separação cromatográfica, favoreceram a seletividade e detectabilidade do método LC-MS/MS no modo column switching. Este método quando comparado ao de referência PPT/LC-MS/MS, através da análise de 10 amostras de pacientes esquizofrênicos, não apresentou diferença significativa (teste t) entre as concentrações plasmáticas, podendo ser aplicado na monitorização terapêutica. Além deste fato, este método automatizado favoreceu a precisão, a exatidão e a freqüência analítica. / Schizophrenia is a chronic neuropsychiatric disorder that affects approximately 1% of the world population. According to neurobiological theories, schizophrenia stems from biochemical and structural alterations in the brain due to dysfunction in the glutamatergic, dopaminergic, and serotonergic systems. Determining the concentrations of amino acids and neurotransmitters in plasma samples from schizophrenic patients may assist evaluation of therapy effectiveness. In addition to antipsychotics (the first-line drug in the initial treatment of schizophrenia), most patients concomitantly use other classes of drugs such as antidepressants, anticonvulsants, and anxiolytics to minimize the symptoms associated with this disease. To evaluate treatment efficacy, in this thesis a method based on protein precipitation (PPT) and hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry (HILIC-MS/MS) has been properly developed and validated to determine amino acids (aspartate, serine, glycine, alanine, methionine, leucine, tyrosine, and tryptophan) and neurotransmitters (glutamate and -aminobutyric acid) in plasma samples obtained from 35 schizophrenia patients treated with clozapine (27 patients) or olanzapine (8 patients); 38 healthy volunteers served as controls. The HILIC-MS/MS method was linear for concentrations ranging from the LLOQ (9.7 pmol mL-1 - 13.3 nmol mL-1) to the ULOQ (19.4 nmol mL-1 - 800 nmol mL-1). The analysis time was 3.0 min. In the case of accuracy, RSE ranged from -18 to 19%. As for precision, CV lay between 0.1 and 16% (LLOQ). Analysis of variance (ANOVA) followed by post-hoc Duncan showed that the average methionine serum levels (nmol mL-1) (F2.70 = 3.14, p = 0.049) in schizophrenic patients treated with olanzapine were significantly higher as compared with the control group (healthy volunteers). The glutamate level in schizophrenic patients treated with clozapine tended to higher values (F2.70 = 2.50, p = 0.090). Concerning the analytical methods, PPT/LC-MS/MS and LC-MS/MS operating in the column-switching mode were developed and validated to determine antipsychotic (olanzapine, quetiapine, clozapine, haloperidol, and chlorpromazine), antidepressants (mirtazapine, paroxetine, citalopram, sertraline, imipramine, clomipramine, and fluoxetine), anticonvulsants (carbamazepine and lamotrigine), and anxiolytics (diazepam and clonazepam) in plasma samples taken from schizophrenic patients for therapeutic drug monitoring. A monolithic hybrid column containing silica with cyanopropyl groups in the first dimension was employed. The PPT/LC-MS/MS method was linear from the LLOQ (0.2 ng mL-1 - 5.0 ng mL-1) to the ULOQ (40.5 ng mL-1 - 10.5 g mL-1). In the case of accuracy, RSE ranged from -9.7 to 8.0%; as for precision, CV lay between 0.1 and 12%. LC-MS/MS in the column-switching mode was linear from the LLOQ (63.0 pg mL-1 - 1250.0 pg mL-1) to the ULOQ (40.5 ng mL-1 - 10.5 g mL-1). RSE ranged from -14 to 12%; CV lay between 0.6 and 6.5%. The drugs were selectively pre-concentrated in the monolithic column containing silica incorporated with cyanopropyl groups. For the LC-MS/MS method operating in the column-switching mode, the endogenous components of the biological sample of the LC-MS/MS method were removed before analysis. Analysis of 10 plasma samples obtained from schizophrenic patients did not reveal any significant differences (t test) between the LC-MS/MS method and the reference PPT/LC-MS/MS method. Therefore, LC-MS/MS can be applied in therapeutic monitoring, with the advantage that this method offers improved precision, accuracy, and analytical frequency.

Le méthotrexate (MTX), un agent anti-cancéreux fréquemment utilisé en chimiothérapie, requiert généralement un suivi thérapeutique de la médication (Therapeutic Drug Monitoring, TDM) pour surveiller son niveau sanguin chez le patient afin de maximiser son efficacité tout en limitant ses effets secondaires. Malgré la fenêtre thérapeutique étroite entre l’efficacité et la toxicité, le MTX reste, à ce jour, un des agents anti-cancéreux les plus utilisés au monde. Les techniques analytiques existantes pour le TDM du MTX sont coûteuses, requièrent temps et efforts, sans nécessairement fournir promptement les résultats dans le délai requis. Afin d’accélérer le processus de dosage du MTX en TDM, une stratégie a été proposée basée sur un essai compétitif caractérisé principalement par le couplage plasmonique d’une surface métallique et de nanoparticules d’or. Plus précisément, l’essai quantitatif exploite la réaction de compétition entre le MTX et une nanoparticule d’or fonctionnalisée avec l’acide folique (FA-AuNP) ayant une affinité pour un récepteur moléculaire, la réductase humaine de dihydrofolate (hDHFR), une enzyme associée aux maladies prolifératives. Le MTX libre mixé avec les FA-AuNP, entre en compétition pour les sites de liaison de hDHFR immobilisés sur une surface active en SPR ou libres en solution. Par la suite, les FA-AuNP liées au hDHFR fournissent une amplification du signal qui est inversement proportionnelle à la concentration de MTX. La résonance des plasmons de surface (SPR) est généralement utilisée comme une technique spectroscopique pour l’interrogation des interactions biomoléculaires. Les instruments SPR commerciaux sont généralement retrouvés dans les grands laboratoires d’analyse. Ils sont également encombrants, coûteux et manquent de sélectivité dans les analyses en matrice complexe. De plus, ceux-ci n’ont pas encore démontré de l’adaptabilité en milieu clinique. Par ailleurs, les analyses SPR des petites molécules comme les médicaments n’ont pas été explorés de manière intensive dû au défi posé par le manque de la sensibilité de la technique pour cette classe de molécules. Les développements récents en science des matériaux et chimie de surfaces exploitant l’intégration des nanoparticules d’or pour l’amplification de la réponse SPR et la chimie de surface peptidique ont démontré le potentiel de franchir les limites posées par le manque de sensibilité et l’adsorption non-spécifique pour les analyses directes dans les milieux biologiques. Ces nouveaux concepts de la technologie SPR seront incorporés à un système SPR miniaturisé et compact pour exécuter des analyses rapides, fiables et sensibles pour le suivi du niveau du MTX dans le sérum de patients durant les traitements de chimiothérapie. L’objectif de cette thèse est d’explorer différentes stratégies pour améliorer l’analyse des médicaments dans les milieux complexes par les biocapteurs SPR et de mettre en perspective le potentiel des biocapteurs SPR comme un outil utile pour le TDM dans le laboratoire clinique ou au chevet du patient. Pour atteindre ces objectifs, un essai compétitif colorimétrique basé sur la résonance des plasmons de surface localisée (LSPR) pour le MTX fut établi avec des nanoparticules d’or marquées avec du FA. Ensuite, cet essai compétitif colorimétrique en solution fut adapté à une plateforme SPR. Pour les deux essais développés, la sensibilité, sélectivité, limite de détection, l’optimisation de la gamme dynamique et l’analyse du MTX dans les milieux complexes ont été inspectés. De plus, le prototype de la plateforme SPR miniaturisée fut validé par sa performance équivalente aux systèmes SPR existants ainsi que son utilité pour analyser les échantillons cliniques des patients sous chimiothérapie du MTX. Les concentrations de MTX obtenues par le prototype furent comparées avec des techniques standards, soit un essai immunologique basé sur la polarisation en fluorescence (FPIA) et la chromatographie liquide couplée avec de la spectrométrie de masse en tandem (LC-MS/MS) pour valider l’utilité du prototype comme un outil clinique pour les tests rapides de quantification du MTX. En dernier lieu, le déploiement du prototype à un laboratoire de biochimie dans un hôpital démontre l’énorme potentiel des biocapteurs SPR pour utilisation en milieux clinique. / Methotrexate (MTX) cancer therapy requires therapeutic drug monitoring (TDM) for following its levels in a patient during the course of treatment in order to maximize efficacy while minimizing side effects. Despite its narrow therapeutic window, MTX remains until this date, one of the most employed chemotherapy agents. Existing TDM analytical techniques for MTX are costly, time-consuming and labor intensive which are not suitable to promptly generate results within the therapy timeframe. To provide rapid MTX quantification for TDM, a strategy is proposed based on a competitive assay featuring gold nanoparticles and surface plasmonic coupling. More specifically, the inhibition of MTX with its molecular receptor, human dihydrofolate reductase (hDHFR), an enzyme associated with proliferative diseases, is explored. Free MTX mixed with folic acid-functionalized gold nanoparticles (FA-AuNP) are in competition for hDHFR binding sites immobilized on a SPR active surface or free in solution. FA-AuNP binding to hDHFR provides signal amplification which is inversely proportional to the concentration of MTX. Surface plasmon resonance (SPR) is commonly used as a spectroscopic technique for the interrogation of biomolecular interactions. Current commercial SPR instruments are laboratory-based, bulky, expensive, lack sensitivity in complex matrix and have not shown adaptability in clinical settings. In addition, SPR analysis of small molecules such as drugs has not been extensively explored due to lack of sensitivity. The recent advances in materials science and surface chemistry exploiting gold nanoparticle integration for SPR response enhancement and peptide surface chemistry have shown potential in overcoming the poor sensitivity and surface-fouling limitations for crude biofluids analysis. These novel concepts of SPR technology are incorporated with a miniaturized fully integrated SPR prototype to conduct fast, reliable and sensitive analysis to monitor MTX levels of a patient undergoing chemotherapy. The objective of the thesis is to explore different strategies in improving drug analysis in a complex matrix using SPR biosensors and to put in perspective of the potential of SPR biosensors as a useful TDM tool in clinical laboratories or at a point-of-care situation. To achieve these objectives, a colorimetric solution-based MTX competitive assay is first established with FA-AuNP. Then, the solution-based MTX competitive assay is translated onto a SPR platform. For both developed assays, sensitivity, selectivity, detection limit, dynamic range optimization as well as analysis of methotrexate in complex matrix are inspected. Furthermore, the SPR prototype is validated by its equivalent performance to existing SPR systems and by its utility in executing MTX analysis in actual serum samples from patients undergoing chemotherapy. The concentrations of MTX obtained by SPR biosensing are compared to standard techniques: fluorescence polarization immunoassay (FPIA) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in order to confirm the feasibility of SPR biosensors as a useful clinical tool for performing rapid MTX concentration evaluation. Finally, the successful deployment of the prototype to a hospital laboratory demonstrates enormous prospective of SPR biosensors in clinical use.

No description available.

A esquizofrenia é um transtorno neuropsiquiátrico crônico que afeta aproximadamente 1% da população mundial. As teorias neurobiológicas descrevem que a esquizofrenia é essencialmente causada por alterações bioquímicas e estruturais do cérebro, devido às disfunções nos sistemas glutamatérgico, dopaminérgico e serotoninérgico. Desta forma, a determinação das concentrações de aminoácidos e neurotransmissores em amostras de plasma de pacientes esquizofrênicos pode auxiliar na avaliação da eficácia da terapia. Além dos antipsicóticos, medicação de primeira linha no tratamento inicial da esquizofrenia, a maioria dos pacientes também faz uso concomitante de outras classes de fármacos, tais como antidepressivos, anticonvulsivantes e ansiolíticos para minimizar os sintomas associados a esta doença. Nesta tese, um método empregando a precipitação de proteínas (PPT) e a cromatografia líquida por interação hidrofílica acoplada à espectrometria de massas em tandem (HILIC-MS/MS) foi adequadamente desenvolvido e validado para a determinação de aminoácidos (aspartato, serina, glicina, alanina, metionina, leucina, tirosina e triptofano) e neurotransmissores (glutamato e ácido -aminobutírico) em amostras de plasma de 35 pacientes esquizofrênicos em tratamento com clozapina (27 pacientes) e olanzapina (8 pacientes) para avaliar a eficácia do tratamento, tendo como controle 38 voluntários sadios. O método HILIC-MS/MS apresentou linearidade do LIQ (9,7 pmol mL-1 - 13,3 nmol mL-1) ao LSQ (19,4 nmol mL-1 - 800 nmol mL-1), tempo de análise de 3,0 min, exatidão com EPR de -18 a 19% e precisão com CV de 0,1 a 16% (LIQ). A análise de variância (ANOVA), seguida por teste post-hoc de Duncan, revelou que os níveis médios plasmáticos (nmol mL-1) de metionina (F2,70 = 3,14, p = 0,049) de pacientes esquizofrênicos em tratamento com olanzapina foram significativamente mais elevados, quando comparados aos valores obtidos com o grupo controle (voluntários saudáveis), já o nível de glutamato em pacientes esquizofrênicos em tratamento com clozapina apresentaram tendência a valores mais altos (F2.70 = 2,50, p = 0,090). Já os métodos, PPT/LC-MS/MS e LC-MS/MS no modo column switching utilizando uma coluna monolítica de sílica híbrida com grupos cianopropil na primeira dimensão, foram desenvolvidos e validados para a determinação dos antipsicóticos (olanzapina, quetiapina, clozapina, haloperidol e clorpromazina), antidepressivos (mirtazapina, paroxetina, citalopram, sertralina, imipramina, clomipramina e fluoxetina), anticonvulsivantes (carbamazepina e lamotrigina), e ansiolíticos (diazepam e clonazepam) em amostras de plasma de pacientes esquizofrênicos para fins de monitorização terapêutica. O método PPT/LC-MS/MS apresentou linearidade do LIQ (0,2 ng mL-1 - 5,0 ng mL-1) ao LSQ (40,5 ng mL-1 - 10,5 g mL-1), exatidão com EPR de -9,7 a 8,0%, e precisão com CV de 0,1 a 12%. Já o método LC-MS/MS no modo column switching apresentou linearidade do LIQ (63,0 pg mL-1 - 1250,0 pg mL-1) ao LSQ (40,5 ng mL-1 - 10,5 g mL-1), exatidão com EPR de -14 a 12% e precisão com CV de 0,6 a 6,5%. A pré-concentração seletiva dos fármacos na coluna monolítica com grupos cianopropil incorporados e a remoção dos componentes endógenos da amostra biológica, antes da separação cromatográfica, favoreceram a seletividade e detectabilidade do método LC-MS/MS no modo column switching. Este método quando comparado ao de referência PPT/LC-MS/MS, através da análise de 10 amostras de pacientes esquizofrênicos, não apresentou diferença significativa (teste t) entre as concentrações plasmáticas, podendo ser aplicado na monitorização terapêutica. Além deste fato, este método automatizado favoreceu a precisão, a exatidão e a freqüência analítica. / Schizophrenia is a chronic neuropsychiatric disorder that affects approximately 1% of the world population. According to neurobiological theories, schizophrenia stems from biochemical and structural alterations in the brain due to dysfunction in the glutamatergic, dopaminergic, and serotonergic systems. Determining the concentrations of amino acids and neurotransmitters in plasma samples from schizophrenic patients may assist evaluation of therapy effectiveness. In addition to antipsychotics (the first-line drug in the initial treatment of schizophrenia), most patients concomitantly use other classes of drugs such as antidepressants, anticonvulsants, and anxiolytics to minimize the symptoms associated with this disease. To evaluate treatment efficacy, in this thesis a method based on protein precipitation (PPT) and hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry (HILIC-MS/MS) has been properly developed and validated to determine amino acids (aspartate, serine, glycine, alanine, methionine, leucine, tyrosine, and tryptophan) and neurotransmitters (glutamate and -aminobutyric acid) in plasma samples obtained from 35 schizophrenia patients treated with clozapine (27 patients) or olanzapine (8 patients); 38 healthy volunteers served as controls. The HILIC-MS/MS method was linear for concentrations ranging from the LLOQ (9.7 pmol mL-1 - 13.3 nmol mL-1) to the ULOQ (19.4 nmol mL-1 - 800 nmol mL-1). The analysis time was 3.0 min. In the case of accuracy, RSE ranged from -18 to 19%. As for precision, CV lay between 0.1 and 16% (LLOQ). Analysis of variance (ANOVA) followed by post-hoc Duncan showed that the average methionine serum levels (nmol mL-1) (F2.70 = 3.14, p = 0.049) in schizophrenic patients treated with olanzapine were significantly higher as compared with the control group (healthy volunteers). The glutamate level in schizophrenic patients treated with clozapine tended to higher values (F2.70 = 2.50, p = 0.090). Concerning the analytical methods, PPT/LC-MS/MS and LC-MS/MS operating in the column-switching mode were developed and validated to determine antipsychotic (olanzapine, quetiapine, clozapine, haloperidol, and chlorpromazine), antidepressants (mirtazapine, paroxetine, citalopram, sertraline, imipramine, clomipramine, and fluoxetine), anticonvulsants (carbamazepine and lamotrigine), and anxiolytics (diazepam and clonazepam) in plasma samples taken from schizophrenic patients for therapeutic drug monitoring. A monolithic hybrid column containing silica with cyanopropyl groups in the first dimension was employed. The PPT/LC-MS/MS method was linear from the LLOQ (0.2 ng mL-1 - 5.0 ng mL-1) to the ULOQ (40.5 ng mL-1 - 10.5 g mL-1). In the case of accuracy, RSE ranged from -9.7 to 8.0%; as for precision, CV lay between 0.1 and 12%. LC-MS/MS in the column-switching mode was linear from the LLOQ (63.0 pg mL-1 - 1250.0 pg mL-1) to the ULOQ (40.5 ng mL-1 - 10.5 g mL-1). RSE ranged from -14 to 12%; CV lay between 0.6 and 6.5%. The drugs were selectively pre-concentrated in the monolithic column containing silica incorporated with cyanopropyl groups. For the LC-MS/MS method operating in the column-switching mode, the endogenous components of the biological sample of the LC-MS/MS method were removed before analysis. Analysis of 10 plasma samples obtained from schizophrenic patients did not reveal any significant differences (t test) between the LC-MS/MS method and the reference PPT/LC-MS/MS method. Therefore, LC-MS/MS can be applied in therapeutic monitoring, with the advantage that this method offers improved precision, accuracy, and analytical frequency.