The physiological role of LCAT has been the subject of a number of recent articles (Glomset, 1979; Nilsson-Ehle et al., 1980). According to most current theories, the enzyme functions in combination with high-density lipoproteins in the reverse cholesterol transport pathway which presumably returns peripheral cholesterol to the liver where cholesterol catabolism takes place. Despite the exciting potential for studies on the catalytic function and the nature of the enzyme-substrate complex, the mechanism of action of LCAT remains largely unexplored. The relatively slow progress in the elucidation of the LCAT reaction mechanism is likely to be due to the difficulties in the isolation of the enzyme in sufficient quantities. Consequently, considerably less is known about the physical and chemical properties of the enzyme. Therefore, the first objective of this investigation was to isolate and purify sufficient amount of enzyme for subsequent characterization studies. The second objective of this investigation was to characterize the physical properties of the enzyme by techniques including analytical ultracentrifugation, ultraviolet spectroscopy, and circular dichroism and fluorescence spectroscopy. The third objective of this investigation was to characterize the chemical properties of the enzyme which deals with the amino acid and carbohydrate composition and with some basic structural features that are related to the chemical composition of LCAT.

Huian plasma high-density lipoprotein (HDL) were isolated by a procedure employing polyanion precipitation and column chromatography. Lipid and protein composition of the HDL isolated by this method was found to be similar to another HDL preparation isolated by ultracentrifugation. However, minor differences were noted, including a higher phospholipid and apoproteinE content and lower triglyceride content of the HDL isolated by column chromatography. Four subfraction of HDL were obtained following chromatography on an anion exchange column. The subfraction four had the highest esterified to free cholesterol ratio, the second highest phospholipid to unesterified cholesterol, and the lowest molecular weight. In addition it was consistently coincided with lecithin: cholesterol acyltransferase (LCAT) activity and found to be the best substrate for the enzyme.

Desenvolveu-se método de alta sensibilidade e especificidade por cromatografia liquida de alta eficiência acoplada a detecção por espectrometria de massas (LC-MS/MS) para quantificação do lorazepam em plasma humano visando aplicação em estudo de bioequivalência entre duas formulações de comprimidos contendo esse fármaco. A preparação das amostras de plasma foi feita por extração líquido-líquido usando hexano:diclorometano (60:40 v/v) como solvente de extração. O padrão interno usado foi o bromazepam. A separação cromatográfica ocorreu utilizando-se coluna analítica modelo Gemini® C18 110 A (150 mm x 4,6 mm; partículas de 5µm). Mistura de metanol e tampão acetato de amônio 10 mM (80:20, v/v), acrescida de 0,1% de ácido fórmico ao final da preparação, foi usada como fase móvel. A interface entre HPLC e MS/MS foi a fonte de ionização por eletrospray (ESI) operando em modo positivo (ES+). O analito e o PI foram monitorados e quantificados através de multiple reaction monitoring (MRM). As transições monitoradas foram m/z 320,69 > 274,96 para o lorazepam e m/z 318,00 > 182,20 para o padrão interno. O método foi validado na faixa de concentração de 0,50 a 80,0 ng/ml em plasma humano. A bioequivalência entre as formulações foi determinada através dos intervalos de confiança 90 % obtidos para as razões dos parâmetros farmacocinéticos Cmax (99% - 114%), AUC0-t (93% - 105%) e AUC0-inf (96% - 107%). Concluiu-se que as duas formulações podem ser administradas de maneira intercambiável sem prejuízo da eficácia terapêutica. / A method of liquid chromatography coupled to mass spectrometric detection (LC-MS/MS) with high sensitivity and specificity was developed to quantify Lorazepam in human plasma. This method was applied in a bioequivalence study between two tablet formulations. The preparation of plasma samples were performed by liquid-liquid extraction using hexanedichloromethane (60:40 v/v) as extraction solvent. The internal standard was bromoazepam. The chromatographic separation was achieved using the Gemini® C18 110A (150 mm x 4.6mm; 5µm particles) analytical column. The mobile phase was prepared from a mixture of methanol and 10mM of ammonium acetate (80:20, v/v), and finally adding 0.1% of formic acid. The HPLC and MS/MS interface was the electrospray ionization source (ESI), operating in positive mode (ESI+). The analyte and internal standard were monitored and quantified through multiple reaction monitoring (MRM). The monitored transitions were m/z 320.69 > 274.96 for lorazepam and m/z 318.00 > 182.20 for the internal standard. The method was validated over the range 0.50 to 80.0 ng/mL in human plasma. The bioequivalence between the two formulations was determined inside the 90% confidence interval for the pharmacokinetic parameters, Cmax (99% - 114%), AUC0-t (93% - 105%) and AUC0-inf (96% - 107%). It was concluded that the two formulations can be administered in an interchangeable manner without losing the therapeutic efficiency.

Desenvolveu-se método de alta sensibilidade e especificidade por cromatografia liquida de alta eficiência acoplada a detecção por espectrometria de massas (LC-MS/MS) para quantificação do lorazepam em plasma humano visando aplicação em estudo de bioequivalência entre duas formulações de comprimidos contendo esse fármaco. A preparação das amostras de plasma foi feita por extração líquido-líquido usando hexano:diclorometano (60:40 v/v) como solvente de extração. O padrão interno usado foi o bromazepam. A separação cromatográfica ocorreu utilizando-se coluna analítica modelo Gemini® C18 110 A (150 mm x 4,6 mm; partículas de 5µm). Mistura de metanol e tampão acetato de amônio 10 mM (80:20, v/v), acrescida de 0,1% de ácido fórmico ao final da preparação, foi usada como fase móvel. A interface entre HPLC e MS/MS foi a fonte de ionização por eletrospray (ESI) operando em modo positivo (ES+). O analito e o PI foram monitorados e quantificados através de multiple reaction monitoring (MRM). As transições monitoradas foram m/z 320,69 > 274,96 para o lorazepam e m/z 318,00 > 182,20 para o padrão interno. O método foi validado na faixa de concentração de 0,50 a 80,0 ng/ml em plasma humano. A bioequivalência entre as formulações foi determinada através dos intervalos de confiança 90 % obtidos para as razões dos parâmetros farmacocinéticos Cmax (99% - 114%), AUC0-t (93% - 105%) e AUC0-inf (96% - 107%). Concluiu-se que as duas formulações podem ser administradas de maneira intercambiável sem prejuízo da eficácia terapêutica. / A method of liquid chromatography coupled to mass spectrometric detection (LC-MS/MS) with high sensitivity and specificity was developed to quantify Lorazepam in human plasma. This method was applied in a bioequivalence study between two tablet formulations. The preparation of plasma samples were performed by liquid-liquid extraction using hexanedichloromethane (60:40 v/v) as extraction solvent. The internal standard was bromoazepam. The chromatographic separation was achieved using the Gemini® C18 110A (150 mm x 4.6mm; 5µm particles) analytical column. The mobile phase was prepared from a mixture of methanol and 10mM of ammonium acetate (80:20, v/v), and finally adding 0.1% of formic acid. The HPLC and MS/MS interface was the electrospray ionization source (ESI), operating in positive mode (ESI+). The analyte and internal standard were monitored and quantified through multiple reaction monitoring (MRM). The monitored transitions were m/z 320.69 > 274.96 for lorazepam and m/z 318.00 > 182.20 for the internal standard. The method was validated over the range 0.50 to 80.0 ng/mL in human plasma. The bioequivalence between the two formulations was determined inside the 90% confidence interval for the pharmacokinetic parameters, Cmax (99% - 114%), AUC0-t (93% - 105%) and AUC0-inf (96% - 107%). It was concluded that the two formulations can be administered in an interchangeable manner without losing the therapeutic efficiency.

La quantification des anticorps monoclonaux (mAbs) dans le plasma est un pré-requis essentiel pour les études PK/PD. Les méthodes de références pour quantifier actuellement les mAbs sont de type ELISA mais les difficultés rencontrées notamment lorsque l’analyse porte sur des mAbs dont la cible pharmacologique est circulante, suggèrent que la spectrométrie de masse serait une alternative intéressante. Appliquée au bevacizumab, la stratégie développée fait appel à la spectrométrie de masse en tandem utilisée en mode MRM (HPLC-ESI-QqQ) et porte sur l’analyse des peptides spécifiques du bevacizumab obtenus à l’issu d’une protéolyse trypsique. La quantification absolue est réalisée à l’aide d’une droite de calibration obtenue à partir du ratio des aires des peptides du bevacizumab et de l’étalon interne. Afin de proposer une méthodologie de quantification de référence, nous avons définie les points clés du développement pour la transposition à d’autre mAbs et comparé les deux stratégies d’étalonnage interne les plus employées : l’une utilisant une protéine analogue et l’autre un peptide marqué par des isotopes stables (SIL-peptide). A travers ce développement la stratégie proposée présente un caractère universel vis-à-vis des anticorps monoclonaux de type IgG dont le traitement des échantillons repose sur une purification par protéine A suivit d’une concentration par ultrafiltration et dont la quantification fait appel à l’approche d’étalonnage interne SIL-peptide. Validée selon les recommandations de la FDA, notre méthode présente les performances analytiques attendues en termes de sensibilité, répétabilité et spécificité pour être appliquée à des études cliniques. / The quantification in plasma of monoclonal antibodies (mAbs) is an essential prerequisite to any PK/PD preclinical and clinical study. To date, reference techniques used to quantify mAbs, rely on enzyme-linked immunosorbent assay (ELISA) but the difficulties encountered in particular when the analysis focuses on the mAbs whose pharmacological target is circulating, suggest that mass spectrometry would be an interesting alternative. Applied to bevacizumab, the quantification developed strategy involves tandem mass spectrometry (HPLC-ESI-QqQ) used in MRM mode and focuses on the analysis of specific peptides bevacizumab obtained after tryptic proteolysis. Absolute quantification is achieved through calibration curve obtained from peak area ratios of bevacizumab surrogate peptide and internal standard. To propose a reference quantification methodology, we have identified the key points of development for transposition to other mAbs and compared the two most commonly used internal calibration approaches: one using protein analogue and the other a stable isotope labeled surrogate peptide (SIL-peptide). Through this development, the proposed strategy has a universal character with respect to IgG monoclonal antibodies subclasses which is based on sample processing purification using protein A followed by concentration by ultra filtration and whose quantification involves the internal calibration approach SIL-peptide. Validated according to FDA guidelines, our method shows the expected analytical performance in terms of sensitivity, specificity and repeatability for application in clinical studies

Etoricoxib is a non-steroidal anti-inflammatory drug, from the coxibs group, that represents a second-generation of COX-2 inhibitors, used for the treatment of arthritis and pain. The methodologies for the evaluation of etoricoxib in pharmaceutical products and plasma were developed and validated in the present work. The reversed-phase liquid chromatography (RP-LC) analysis was carried out using a Synergi fusion C18 column (150 mm x 4.6 mm), maintained at a controlled-ambient temperature. The mobile phase consisted of phosphoric acid 0.01 M, pH 3.0/acetonitrile (62:38, V/V), run at a flow rate of 1.0 mL/min with detection at 234 nm. The chromatographic separation was obtained within 7.0 min and it was linear in the concentration range of 0.02-150 µg/mL. The liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated using a Luna C18 column (50 mm x 3.0 mm), maintained at 40 ºC and the mobile phase consisted of acetonitrile:water (95:5, V/V)/ 0.1% acetic acid (90:10, V/V), run at flow rate of 0.4 mL/min. The mass spectrometer, equipped with electrospray positive source, was used in multiple reaction monitoring mode (MRM), monitoring the transitions of 359.3>280.0 and 332.0>95.0, for etoricoxib and piroxicam (internal standard), respectively. The chromatographic separation was obtained within 2.0 min and it was linear in the concentration range of 1-5000 ng/mL. The procedures were validated evaluating parameters such as the specificity, linearity, precision, accuracy, robustness, limit of detection and limit of quantitation. Besides, for the bioanalytical method, the matrix effects, recovery and stability studies were also analyzed, giving results within the acceptable range. The proposed methods were applied for the analysis of pharmaceutical products, showing significant correlation (r=0.9999) of the results. Moreover, the liquid-liquid and solid phase extraction methods developed and optimized allowed high mean recoveries of etoricoxib and internal standard from the plasma samples. The procedures can be applied for the biovailability studies and for the quality control of pharmaceutical products. / Etoricoxibe é um antiinflamatório não esteroidal, pertencente ao grupo dos coxibes, que representa a segunda geração dos inibidores seletivos da cicloxigenase-2. É indicado para o tratamento de artrites e dor aguda. No presente trabalho foram desenvolvidas e validadas metodologias para avaliação de etoricoxibe em produtos farmacêuticos e plasma humano. As análises por cromatografia líquida em fase reversa (CL-FR) foram realizadas utilizando coluna Synergi fusion C18 (150 mm x 4,6 mm), mantida a temperatura ambiente. A fase móvel foi composta de ácido fosfórico 0,01 M, pH 3,0/acetonitrila (62:38, V/V) na vazão de 1,0 mL/min e detecção no ultravioleta a 234 nm. A separação cromatográfica foi obtida no tempo de 7 minutos, sendo linear na faixa de concentração de 0,02-150 µg/mL. Paralelamente, desenvolveu-se e validou-se método por cromatografia líquida combinada à espectrometria de massas (CL-EM/EM). Realizaram-se as análises utilizando Luna C18 (50 mm x 4,6 mm), mantida a 40 ºC e fase móvel composta de acetonitrila:água (95:5, V/V)/ 0,1% ácido acético (90:10, V/V), na vazão de 0,4 mL/min. O espectrômetro de massas, equipado com fonte de electrospray positivo, foi empregado no modo de monitoramento de reação múltipla (MRM), monitorando as transições de 359,3>280,0 e 332,0>95,0, para o etoricoxibe e piroxicam (padrão interno), respectivamente. A separação cromatográfica foi obtida em 2 minutos, sendo linear na faixa de concentração de 1-5000 ng/mL. Os procedimentos foram validados, avaliando-se os parâmetros de especificidade, linearidade, precisão, exatidão, robustez, limite de detecção e quantificação, incluindo para o método bioanalítico os efeitos de matriz, a recuperação e estudos de estabilidade, cujos resultados cumpriram os requisitos preconizados. Os métodos propostos foram utilizados na análise de produtos farmacêuticos, demonstrando correlação significativa dos resultados (r=0,9999). Além disso, os métodos de extração líquido-líquido e em fase sólida desenvolvidos e otimizados propiciaram significativas percentagens de recuperação do etoricoxibe e do padrão interno nas amostras de plasma. Os procedimentos pesquisados podem ser aplicados para estudos de biodisponibilidade e para aprimorar o controle da qualidade de medicamentos.

Ezetimibe selectively inhibits the intestinal absorption of dietary cholesterol and related plant sterols, from the 2-azetidinones group, and is used for the treatment of hypercholesterolemia and phytosterolemia. The methodologies for the evaluation of ezetimibe in pharmaceutical products and plasma were developed and validated in the present work. The reversed-phase liquid chromatography (RP-LC) analysis was carried out using a Synergi fusion C18 column (150 mm x 4.6 mm), maintained at 45 oC. The mobile phase consisted of potassium phosphate buffer 0.03 M, pH 4.5/acetonitrile (35:65, V/V), run at a flow rate of 0.6 mL/min with detection at 234 nm. The chromatographic separation was obtained within 15 min and it was linear in the concentration range of 0.5-200 Hg/mL. The method was sucessfuly applied for the simultaneous determination of ezetimibe and simvastatin in pharmaceutical products. The liquid chromatography-tandem mass spectrometry (LCMS/ MS) method was developed and validated using a Luna C18 column (50 mm x 3.0 mm) and the mobile phase consisted of acetonitrile:water (85:15, V/V), run at a flow rate of 0.4 mL/min. The mass spectrometer, equipped with electrospray positive source, was used in multiple reaction monitoring mode (MRM), monitoring the transitions of 392.0>161.0 and 359.3>280.0, for ezetimibe and etoricoxib (internal standard), respectively. The chromatographic separation was obtained within 2 min and it was linear in the concentration range of 0.25-20 ng/mL (ezetimibe) and 1-300 ng/mL (ezetimibe and its glucuronide matabolite). The procedures were validated evaluating parameters such as the specificity, linearity, precision, accuracy, robustness, limit of detection and limit of quantitation. Besides, for the bioanalytical method, the matrix effects, recovery and stability studies were also analyzed, giving results within the acceptable range. The proposed method was applied for the analysis of pharmaceutical products, showing significant correlation (P>0.05) of the results. Moreover, the liquid-liquid extraction method developed and optimized allowed high mean recoveries of ezetimibe and internal standard from the plasma samples. The procedures can be applied for the biovailability studies and for the quality control of pharmaceutical products. / Ezetimiba é um inibidor seletivo da absorção intestinal do colesterol e de fitosteróis, pertencente ao grupo das 2-ezetidinonas, indicado para o tratamento da hipercolesterolemia e fitosterolemia. No presente trabalho foram desenvolvidas e validadas metodologias para avaliação de ezetimiba em produtos farmacêuticos e plasma humano. As análises por cromatografia líquida em fase reversa (CL-FR) foram realizadas utilizando coluna Synergi fusion C18 (150 mm x 4,6 mm), mantida a 45 oC. A fase móvel foi composta de tampão fosfato de potássio 0,03 M, pH 4,5/acetonitrila (35:65, V/V), eluída na vazão de 0,6 mL/min e detecção no ultravioleta a 234 nm. A separação cromatográfica foi obtida no tempo de 15 minutos, sendo linear na faixa de concentração de 0,5-200 Hg/mL. O método foi aplicado para análise simultânea de ezetimiba e sinvastatina em produtos farmacêuticos comerciais. Paralelamente, desenvolveu-se e validou-se método por cromatografia líquida combinada à espectrometria de massas (CL-EM/EM). Executaram-se as análises utilizando coluna Luna C18 (50 mm x 4,6 mm) e fase móvel composta de acetonitrila:água (85:15, V/V) na vazão de 0,4 mL/min. O espectrômetro de massas, equipado com fonte de electrospray positivo, foi empregado no modo de monitoramento de reação múltipla (MRM), monitorando as transições de 392,0>161,0 e 359,3>280,0, para a ezetimiba e etoricoxibe (padrão interno), respectivamente. A separação cromatográfica foi obtida em 2 minutos, sendo linear nas faixas de concentração de 0,25-20 ng/mL (ezetimiba) e 1-300 ng/mL (ezetimiba e seu metabólito). Os procedimentos foram validados, avaliando-se os parâmetros de especificidade, linearidade, precisão, exatidão, robustez, limite de detecção e quantificação, incluindo para o método bioanalítico os efeitos de matriz, recuperação e estudos de estabilidade, cujos resultados cumpriram os requisitos preconizados. O método proposto foi utilizado na análise de produtos farmacêuticos, demonstrando correlação significativa dos resultados (P>0,05). Além disso, o método de extração líquido-líquido desenvolvido e otimizado propiciou significativa percentagem de recuperação da ezetimiba, seu metabólito e do padrão interno nas amostras de plasma. Os procedimentos pesquisados podem ser aplicados para estudos de biodisponibilidade e para aprimorar o controle da qualidade de medicamentos.

The studies in the present thesis explored the feasibility of using nanocellulose-based filters in virus removal filtration of plasma-derived proteins.   In Paper I, two-step nanofiltration of commercially available human serum albumin (HSA) product, which was diluted to 10 g L-1 by phosphate buffer saline (PBS) and adjusted pH to 7.4, was performed to remove soluble protein aggregates and reduce filter fouling. The two-step filtration of HSA employed nanocellulose-based filters of varying thickness, i.e. 11 μm and 22 μm filters.  The removal of HSA aggregates during filtration through 11 μm pre-filters dramatically improves the flow properties of the 22 μm filter, enabling high protein throughput and high virus clearance. A distribution of pore sizes between 50 nm and 80 nm, which is present in the 11 μm filter and is absent in the 22 μm filter, plays a crucial part in removing the HSA aggregates. With respect to virus filtration, 1 bar constant trans-membrane pressure filtration shows poor removal ability of ΦX174 bacteriophage (28 nm), i.e., log10 reduction value (LRV) ≤ 3.75, while that at 3 bar and 5 bar achieves LRV[MOU1] [LW2]  > 5 model virus clearance and overall rapid filtration. Removal of protein aggregates during bioprocessing of HSA products is key to improving the filtration flux, which makes it possible to apply virus removal filtration for HSA to ensure its virus safety.   In Paper II, nanofiltration of human plasma-derived intravenous immuno-globulin (IVIG) intermediate (11.26 g L-1, pH 4.9) was carried out to demonstrate high product recovery and high model virus clearance. Virus removal filtration of industrial-grade human IVIG was achieved using 33μm filters at both low (60 Lm-2) and high (288 Lm-2) volumetric load. No changes in IVIG structure were detected and high product recovery was recorded. High virus clearance (LRV ≥ 5-6) was achieved for the small-size model viruses (ΦX174 and MS2 bacteriophages) during the load volume of 60 Lm-2. Side-by-side comparisons with commercial virus removal filters suggest that the nanocellulose-based filter paper presents great potential for industrial bioprocessing of plasma-derived IVIG.   In Paper III, process analytical technology (PAT) approach was employed to identify the critical filter parameters, e.g. thickness, basis weight, pore size, and flux, affecting model virus removal efficiency using filters produced by different hot presses.  The quality parameters were analyzed with ANOVA and Shewhart charts. Compared with other studied parameters, the hydraulic flux appears as the most relevant final product quality attribute of the nanocellulose-based filter paper to reflect the virus removal efficiency. In particular, a 15% higher flux may be associated with a 0.5-1.0 log10 reduced virus clearance (p=0.007). The results are highlight the importance of continued systematic studies in quality assurance using statistical process control tools  [MOU1]Define LRV  [LW2]Defined in the line above

Protein carbonylation, a marker of excessive oxidative stress, has been studied in the context of multiple human diseases related to oxidative stress. The variety of post-translational carbonyl modifications (carbonyl PTMs) and their low concentrations in plasma challenge their reproducible identification and quantitation. However, carbonyl-specific biotinylated derivatization tags (e.g., aldehyde reactive probe, ARP) allow for targeting carbonyl PTMs by enriching proteins and peptides carrying these modifications. In this study, an oxidized human serum albumin protein model (OxHSA) and plasma from a healthy donor were derivatized with ARP, digested with trypsin, and enriched using biotin-avidin affinity chromatography prior to nano reversed-phase chromatography coupled online to electrospray ionization tandem mass spectrometry with travelling wave ion mobility spectrometry (nRPC-ESI-MS/MS-TWIMS). The presented workflow addresses several analytical challenges by using ARP-specific fragment ions to reliably identify ARP peptides. Furthermore, the reproducible recovery and relative quantitation of ARP peptides were validated. Human serum albumin (HSA) in plasma was heavily modified by a variety of direct amino acid oxidation products and adducts from reactive carbonyl species (RCS), with most RCS modifications being detected in six hotspots, i.e., Lys10, Lys190, Lys199, Lys281, Lys432, and Lys525 of mature HSA.

A lamotrigina (LTG) é um fármaco pertencente à classe das feniltriazinas utilizado no tratamento de crises epilépticas generalizadas e focais e no tratamento adjunto da epilepsia refratária. Devido à alta variabilidade interindividual, às interações medicamentosas e aos efeitos adversos apresentados durante a administração da LTG, a monitorização terapêutica nos pacientes que fazem uso deste fármaco é necessária para ajuste de dose individual e evitar os efeitos adversos. Assim, o objetivo deste trabalho foi a avaliação de duas técnicas de microextração: a microextração em fase líquida com fibras ocas (HF-LPME) e a microextração líquido-líquido dispersiva (DLLME) para análise da lamotrigina em amostras de plasma de pacientes epilépticos. Primeiramente foram definidas as condições eletroforéticas: foi utilizado um capilar de sílica fundida de 75 ?m de diâmetro interno e 50 cm de comprimento efetivo. O eletrólito de corrida (BGE) foi composto por ácido 2-morfolinoetanosulfônico (MES), na concentração de 130 mmol L-1 e pH 5,0. As análises foram realizadas à temperatura de 20°C e tensão de 15 kV. A amostra foi injetada hidrodinamicamente (0,5 psi por 10 s) e a detecção foi feita em 214 nm. Nestas condições a LTG e o padrão interno (PI), lidocaína, puderam ser analisados em menos de 7 minutos. A HF-LPME foi avaliada no modo de 3 fases, usando 500 ?L de plasma e 3,5 mL de solução fosfato de sódio 50 mmol L-1 pH 9,0 como fase doadora. O solvente utilizado para impregnar a fibra foi o 1-octanol. Como fase aceptora foram utilizados 60 ?L de solução de ácido clorídrico pH 4,0. Para avaliação da DLLME, foi necessária uma etapa de pré-tratamento da amostra (500 ?L de plasma) com 1 mL de acetonitrila. Após isto, 1,3 mL do sobrenadante foram adicionados a 4 mL de solução fosfato de sódio 50 mmol L-1 pH 9,0 e 120 ?L de clorofórmio (solvente extrator) foram injetados nesta amostra aquosa e 165 ?L de fase sedimentada foram recuperados. As características de desempenho analítico para ambos os métodos foram avaliadas, sendo obtida linearidade na faixa de concentração plasmática de 1-20 ?g/mL e limite inferior de quantificação (LIQ) de 1 ?g mL-1. Os ensaios de precisão e exatidão apresentaram valores de acordo com os guias oficiais. Além disso, os métodos foram seletivos, não apresentaram efeito residual e as amostras foram estáveis. Os valores de recuperação foram de 54,3 e 23% para HF-LPME e DLLME, respectivamente. Os métodos validados foram aplicados com sucesso em amostras de plasma de pacientes epilépticos em tratamento com a LTG. Além disso, as duas técnicas foram comparadas e a HF-LPME apresentou vantagens em relação à DLLME, mostrando ser uma técnica promissora para análise de matrizes complexas, com reduzido consumo de solvente orgânico e possibilidade de automação. / Lamotrigine (LTG) is an antiepileptic drug, which belongs to the class of phenyltriazine that can be used in the treatment of new-onset and refractory epilepsy. Due to its high interindividual variability, drug interactions and the adverse effects presented during the LTG administration, therapeutic drug monitoring is very important to dose adjustment and to avoid toxicity effects. Thus, the goal of this study was to develop and validate two microextraction techniques: the hollow fiber liquid-phase microextraction (HF-LPME) and the dispersive liquid-liquid microextraction (DLLME) to analyze LTG in plasma samples of epileptic patients. First of all, the eletroforetic conditions were optimized. A fused-silica uncoated capillary with 75 ?m internal diameter, and 50 cm effective length was used. The 2-(N-morpholino)ethanesulfonic acid (MES) 130 mmol L-1 pH 5.0 was chosen as background electrolyte (BGE). The temperature and the voltage were kept constant at 20°C and 15 kV respectively. For sample injection, hydrodynamic injection mode was used, with a pressure of 0.5 psi applied for 10 s. The wavelength was set at 214 nm. Under final conditions, LTG and the internal standard (IS) lidocaine were analyzed in less than 7 minutes. HF-LPME was evaluated in the three phase mode. The analyte was extracted from 4.0 mL of a basic donor phase (composed of 500 ?L of plasma and 3.5 mL of sodium phosphate solution 50 mmol L-1 pH 9.0) into an organic phase composed of 1-octanol immobilized in the pores of the hollow fiber, and further into an acidic acceptor phase (hydrochloric acid solution pH 4.0) placed in the lumen of the fiber. To evaluate DLLME, the plasma samples were pretreated to remove the proteins, and 500 ?L of plasma sample was mixed with 1 mL of acetonitrile. After that, 1,3 mL of the upper layer was added to 4 mL of sodium phosphate solution 50 mmol L-1 pH 9.0, and 120 ?L of chloroform (extracting solvent) was rapidly injected in the aqueous sample and 165 ?L of the sedimented phase was collected. Under the optimized conditions, both methods were linear over the plasmatic concentration range of 1.0-20.0 ?g mL-1 and the lower limit of quantification (LLOQ) was 1.0 ?g mL-1. Both methods showed good precision, accuracy, selectivity to LTG, with no carryover and the samples were stable under the studied conditions. The recovery were 54,3 and 23% to HF-LPME and DLLME respectively. The validated methods were successfully applied for the quantification of LTG in plasma samples of epileptic patients. The techniques were compared and HF-LPME was more advantageous for being more suitable to analysis of complex matrices using small amount of organic solvent, and also can be automated.