No description available.

According to the literature, there is a decrease in glial cell number or hypofunction of glial cells in depression. It was also found that both antidepressants and atypical antipsychotics might target glial cells, and that they increase the release of glial-cell-line-derived neurotrophic factor (GDNF) from C6 rat glioma cells (C6 cells). In this project, C6 cells were used as a model for glial cells to investigate the effects of fluoxetine and quetiapine on proliferation and differentiation, and to investigate their effects on the release of GDNF. A combination of quetiapine and fluoxetine was used to study their potential synergistic effect on the release of GDNF from C6 cells. <p>C6 cells were treated with different concentrations of fluoxetine and quetiapine in both normal and serum starvation culture conditions. Under the serum present condition, fluoxetine (25 mM) decreased the number of C6 cells from 24 to 48 h, while quetiapine (25 mM) decreased the cell number only at 48h. Under serum starvation, it was found that fluoxetine (12.5 mM) increased the number of C6 cells from 24 to 48 h treatment; in contrast, quetiapine (25 mM) decreased the number of C6 cells after 48 h treatment. Both fluoxetine and quetiapine inhibited the proliferation of C6 cells under normal and serum starvation conditions. Fluoxetine (12.5 mM) decreased C6 cell death, while quetiapine had no significant effect. Fluoxetine, but not quetiapine, changed the morphology of C6 cells and increased the level of glial fibrillary acidic protein (GFAP), an astrocyte marker. Both fluoxetine (12.5, 25 mM) and quetiapine (25 mM) increased the release of GDNF from C6 cells, and an apparent additive effect was found between quetiapine and fluoxetine in the modulation of release of GDNF from these cells. <p>It was concluded that:<p>1. High concentration (25 mM) of fluoxetine and quetiapine decreased the number of C6 cells under the serum present condition and both drugs inhibited the proliferation of C6 cells.<p>2. Fluoxetine had a protective effect on the C6 cells under serum starvation, and affected the differentiation of C6 cells; this implies that fluoxetine may protect glial cells in vivo and affect their differentiation. <p>3. A high concentration of quetiapine decreased the number of C6 cells and inhibited the proliferation under serum starvation; even though it increased the release of GDNF from C6 cells as did fluoxetine.<p>4. Both quetiapine and fluoxetine increased the release of GDNF from <p>C6 cells under serum starvation. The combination of quetiapine and fluoxetine had an apparent additive effect in the modulation of GDNF release.<p>5. These effects on proliferation & GDNF release may underlie the benefit observed with these drugs in treating depression and schizophrenia.

According to the literature, there is a decrease in glial cell number or hypofunction of glial cells in depression. It was also found that both antidepressants and atypical antipsychotics might target glial cells, and that they increase the release of glial-cell-line-derived neurotrophic factor (GDNF) from C6 rat glioma cells (C6 cells). In this project, C6 cells were used as a model for glial cells to investigate the effects of fluoxetine and quetiapine on proliferation and differentiation, and to investigate their effects on the release of GDNF. A combination of quetiapine and fluoxetine was used to study their potential synergistic effect on the release of GDNF from C6 cells. <p>C6 cells were treated with different concentrations of fluoxetine and quetiapine in both normal and serum starvation culture conditions. Under the serum present condition, fluoxetine (25 mM) decreased the number of C6 cells from 24 to 48 h, while quetiapine (25 mM) decreased the cell number only at 48h. Under serum starvation, it was found that fluoxetine (12.5 mM) increased the number of C6 cells from 24 to 48 h treatment; in contrast, quetiapine (25 mM) decreased the number of C6 cells after 48 h treatment. Both fluoxetine and quetiapine inhibited the proliferation of C6 cells under normal and serum starvation conditions. Fluoxetine (12.5 mM) decreased C6 cell death, while quetiapine had no significant effect. Fluoxetine, but not quetiapine, changed the morphology of C6 cells and increased the level of glial fibrillary acidic protein (GFAP), an astrocyte marker. Both fluoxetine (12.5, 25 mM) and quetiapine (25 mM) increased the release of GDNF from C6 cells, and an apparent additive effect was found between quetiapine and fluoxetine in the modulation of release of GDNF from these cells. <p>It was concluded that:<p>1. High concentration (25 mM) of fluoxetine and quetiapine decreased the number of C6 cells under the serum present condition and both drugs inhibited the proliferation of C6 cells.<p>2. Fluoxetine had a protective effect on the C6 cells under serum starvation, and affected the differentiation of C6 cells; this implies that fluoxetine may protect glial cells in vivo and affect their differentiation. <p>3. A high concentration of quetiapine decreased the number of C6 cells and inhibited the proliferation under serum starvation; even though it increased the release of GDNF from C6 cells as did fluoxetine.<p>4. Both quetiapine and fluoxetine increased the release of GDNF from <p>C6 cells under serum starvation. The combination of quetiapine and fluoxetine had an apparent additive effect in the modulation of GDNF release.<p>5. These effects on proliferation & GDNF release may underlie the benefit observed with these drugs in treating depression and schizophrenia.

O objetivo desta tese de doutorado foi testar psicofármacos tradicionais em aplicações diferentes das originais, tendo por base o conhecimento de seus mecanismos de ação e uma visão clínica focada no temperamento. A primeira parte da tese é constituída pelo ensaio clínico de flunarizina comparado com haloperidol no tratamento de pacientes com esquizofrenia. A segunda parte é composta de três relatos de caso oriundos da prática clínica e que, apesar de freqüentes, não costumam ser objetos de pesquisa. A flunarizina, um bloqueador de canal de cálcio empregado para tratar enxaqueca e vertigem foi escolhida pelo fato dela produzir sinais e sintomas extrapiramidais em pacientes idosos, o que posteriormente foi relacionado a sua propriedade como antagonista dos receptores dopaminérgicos do tipo D2, além da existência de dados em modelos animais que indicavam o seu potencial efeito antipsicótico. A flunarizina foi eficaz como antipsicótico e apresentou um perfil de efeitos adversos favorável, além de ter uma meiavida longa e baixo custo. A segunda parte da tese apresenta relatos de casos clínicos freqüentes, mas pouco estudados no âmbito científico. Nesse sentido propomos uma avaliação do paciente com base no temperamento afetivo e emocional, de acordo com o modelo de temperamento proposto por Lara e Akiskal (2006). O primeiro aborda o uso de baixas doses de risperidona no tratamento de ciúme patológico. O segundo se refere à comorbidade do transtorno obsessivocompulsivo e transtorno bipolar, tratados com divalproato de sódio e lamotrigina. O último artigo aponta para o uso de baixas doses de quetiapina em pacientes com sintomas sublimiares e temperamento hipertímico ou ciclotímico que apresentam desregulação emocional. Em conjunto, nossos resultados reforçam a idéia de que as medicações existentes podem sem mais exploradas para o tratamento de quadros clínicos diferentes das suas indicações originais. / The aim of this thesis was to test traditional drugs in applications different from the original, on the basis the knowledge of the mechanisms of action and a vision clinic focused on temperament. The first part of thesis consists in clinical trial of flunarizine compared with haloperidol in the treatment of patients with schizophrenia. The second part is composed by three case reports from clinical practice and that, despite frequent, not usually are objects of research. Flunarizine, a calcium channel blocker used to treat migraine and vertigo, was chosen because it induces extrapyramidal signs in elder patients which was later related to antagonist properties at dopamine D2 receptors, beyond the existence of data in animal models, which indicated its potential antipsychotic effect. Flunarizine was effective as antipsychotic and it presents a favorable side effects profile, beyond the long half-life and low cost. The second part of the thesis presents reports of frequent cases, but little studied under scientific scope. Therefore, we propose an evaluation of the patient with basis on the affective and emotional temperament, according to the temperament model proposed by Lara and Akiskal (2006). The first deals with the use of low doses of risperidone in the treatment of pathological jealousy. The second refers to the comorbidity of obsessive-compulsive disorder and bipolar disorder, treated with divalproex sodium and lamotrigine. The last article points to the use of low doses of quetiapine in patients with subthreshold symptoms and hyperthymic or cyclothymic temperaments presenting emotional deregulation. Together, our results strengthen the idea that the existing medications can be further explored for the treatment of clinical indications different from their originals.

O objetivo desta tese de doutorado foi testar psicofármacos tradicionais em aplicações diferentes das originais, tendo por base o conhecimento de seus mecanismos de ação e uma visão clínica focada no temperamento. A primeira parte da tese é constituída pelo ensaio clínico de flunarizina comparado com haloperidol no tratamento de pacientes com esquizofrenia. A segunda parte é composta de três relatos de caso oriundos da prática clínica e que, apesar de freqüentes, não costumam ser objetos de pesquisa. A flunarizina, um bloqueador de canal de cálcio empregado para tratar enxaqueca e vertigem foi escolhida pelo fato dela produzir sinais e sintomas extrapiramidais em pacientes idosos, o que posteriormente foi relacionado a sua propriedade como antagonista dos receptores dopaminérgicos do tipo D2, além da existência de dados em modelos animais que indicavam o seu potencial efeito antipsicótico. A flunarizina foi eficaz como antipsicótico e apresentou um perfil de efeitos adversos favorável, além de ter uma meiavida longa e baixo custo. A segunda parte da tese apresenta relatos de casos clínicos freqüentes, mas pouco estudados no âmbito científico. Nesse sentido propomos uma avaliação do paciente com base no temperamento afetivo e emocional, de acordo com o modelo de temperamento proposto por Lara e Akiskal (2006). O primeiro aborda o uso de baixas doses de risperidona no tratamento de ciúme patológico. O segundo se refere à comorbidade do transtorno obsessivocompulsivo e transtorno bipolar, tratados com divalproato de sódio e lamotrigina. O último artigo aponta para o uso de baixas doses de quetiapina em pacientes com sintomas sublimiares e temperamento hipertímico ou ciclotímico que apresentam desregulação emocional. Em conjunto, nossos resultados reforçam a idéia de que as medicações existentes podem sem mais exploradas para o tratamento de quadros clínicos diferentes das suas indicações originais. / The aim of this thesis was to test traditional drugs in applications different from the original, on the basis the knowledge of the mechanisms of action and a vision clinic focused on temperament. The first part of thesis consists in clinical trial of flunarizine compared with haloperidol in the treatment of patients with schizophrenia. The second part is composed by three case reports from clinical practice and that, despite frequent, not usually are objects of research. Flunarizine, a calcium channel blocker used to treat migraine and vertigo, was chosen because it induces extrapyramidal signs in elder patients which was later related to antagonist properties at dopamine D2 receptors, beyond the existence of data in animal models, which indicated its potential antipsychotic effect. Flunarizine was effective as antipsychotic and it presents a favorable side effects profile, beyond the long half-life and low cost. The second part of the thesis presents reports of frequent cases, but little studied under scientific scope. Therefore, we propose an evaluation of the patient with basis on the affective and emotional temperament, according to the temperament model proposed by Lara and Akiskal (2006). The first deals with the use of low doses of risperidone in the treatment of pathological jealousy. The second refers to the comorbidity of obsessive-compulsive disorder and bipolar disorder, treated with divalproex sodium and lamotrigine. The last article points to the use of low doses of quetiapine in patients with subthreshold symptoms and hyperthymic or cyclothymic temperaments presenting emotional deregulation. Together, our results strengthen the idea that the existing medications can be further explored for the treatment of clinical indications different from their originals.

O objetivo desta tese de doutorado foi testar psicofármacos tradicionais em aplicações diferentes das originais, tendo por base o conhecimento de seus mecanismos de ação e uma visão clínica focada no temperamento. A primeira parte da tese é constituída pelo ensaio clínico de flunarizina comparado com haloperidol no tratamento de pacientes com esquizofrenia. A segunda parte é composta de três relatos de caso oriundos da prática clínica e que, apesar de freqüentes, não costumam ser objetos de pesquisa. A flunarizina, um bloqueador de canal de cálcio empregado para tratar enxaqueca e vertigem foi escolhida pelo fato dela produzir sinais e sintomas extrapiramidais em pacientes idosos, o que posteriormente foi relacionado a sua propriedade como antagonista dos receptores dopaminérgicos do tipo D2, além da existência de dados em modelos animais que indicavam o seu potencial efeito antipsicótico. A flunarizina foi eficaz como antipsicótico e apresentou um perfil de efeitos adversos favorável, além de ter uma meiavida longa e baixo custo. A segunda parte da tese apresenta relatos de casos clínicos freqüentes, mas pouco estudados no âmbito científico. Nesse sentido propomos uma avaliação do paciente com base no temperamento afetivo e emocional, de acordo com o modelo de temperamento proposto por Lara e Akiskal (2006). O primeiro aborda o uso de baixas doses de risperidona no tratamento de ciúme patológico. O segundo se refere à comorbidade do transtorno obsessivocompulsivo e transtorno bipolar, tratados com divalproato de sódio e lamotrigina. O último artigo aponta para o uso de baixas doses de quetiapina em pacientes com sintomas sublimiares e temperamento hipertímico ou ciclotímico que apresentam desregulação emocional. Em conjunto, nossos resultados reforçam a idéia de que as medicações existentes podem sem mais exploradas para o tratamento de quadros clínicos diferentes das suas indicações originais. / The aim of this thesis was to test traditional drugs in applications different from the original, on the basis the knowledge of the mechanisms of action and a vision clinic focused on temperament. The first part of thesis consists in clinical trial of flunarizine compared with haloperidol in the treatment of patients with schizophrenia. The second part is composed by three case reports from clinical practice and that, despite frequent, not usually are objects of research. Flunarizine, a calcium channel blocker used to treat migraine and vertigo, was chosen because it induces extrapyramidal signs in elder patients which was later related to antagonist properties at dopamine D2 receptors, beyond the existence of data in animal models, which indicated its potential antipsychotic effect. Flunarizine was effective as antipsychotic and it presents a favorable side effects profile, beyond the long half-life and low cost. The second part of the thesis presents reports of frequent cases, but little studied under scientific scope. Therefore, we propose an evaluation of the patient with basis on the affective and emotional temperament, according to the temperament model proposed by Lara and Akiskal (2006). The first deals with the use of low doses of risperidone in the treatment of pathological jealousy. The second refers to the comorbidity of obsessive-compulsive disorder and bipolar disorder, treated with divalproex sodium and lamotrigine. The last article points to the use of low doses of quetiapine in patients with subthreshold symptoms and hyperthymic or cyclothymic temperaments presenting emotional deregulation. Together, our results strengthen the idea that the existing medications can be further explored for the treatment of clinical indications different from their originals.

Introdução: A barreira hematoencefálica limita a penetração de compostos farmacologicamente ativos para o cérebro devido à presença de zônulas de oclusão no endotélio cerebral e a expressão de transportadores de influxo e efluxo que modulam o acesso de fármacos para o parênquima cerebral. Nanocápsulas de núcleo lipídico (LNC) tem sido estudadas como carreadores de fármacos para o tecido cerebral devido à capacidade de modulação da farmacocinética desses compostos. Entretanto, ainda pouco se sabe sobre os processos envolvidos nas alterações farmacocinéticas e na distribuição tecidual promovidas por esses transportadores. Objetivo: Pretendeu-se investigar as alterações na farmacocinética plasmática e penetração cerebral da quetiapina (QTP) nanoencapsulada em ratos Wistar. Materiais e Métodos: QLNC (1mg/mL) foram obtidas através da metodologia de nanoprecipitação e apresentaram reduzido tamanho de partícula (143 ± 6 nm), baixo indicie de polidispersão (PI < 0.1), alta eficiência de encapsulação (96%), potencial zeta negativo (-7.65 ± 0.815 mV) e pH ácido. QLNC quando visualizadas por MET apresentaram tamanho esférico, homogêneo com ausência de agregados. Os estudos in vivo desse trabalho foram aprovados pelo CEUA/UFRGS. Análise do plasma total e a utilização da microdiálise para determinação das concentrações plasmáticas e cerebrais livres foram realizadas após administração intravenosa da formulação de nanocápsulas de QTP (5 mg /kg ) (QLCN) ou do fármaco em solução (FQ) (5 mg /kg e 10 mg /kg) na presença e na ausência de 30 mg /kg de probenecida (PB), um inibidor de transportadores de membrana. Métodos validados foram utilizados para a quantificação do fármaco em diferentes matrizes. As concentrações cerebral e hepática totais foram investigadas através da técnica de homogeneizado de tecido. Além disso, a fração livre no plasma (fu) e a penetração nos eritrócitos também foi realizada. Resultados: QTP apresentou farmacocinética linear na faixa de doses investigadas, é um substrato para transportadores de efluxo na BHE. Diferenças foram observadas na fu da QTP até 2 h após administração de QLNC indicando que LNC do tipo III promove uma liberação sustentada do fármaco do carreador. QLNC não foi capaz de alterar o coeficiente de partição nos eritrócitos determinado in vitro. As concentrações cerebrais e hepáticas totais foram aumentadas após administração da formulação de nanocápsulas, porém, as concentrações cerebrais livres não foram alteradas em comparação com o QTP em solução. Após administração de PB o fator de penetração da QTP livre no cérebro foi reduzido de 1,55 ± 0.17 para 0,94 ± 0,15. Porém, essa inibição pela probenecida não teve efeito na penetração cerebral de QLNC (0,88 ± 0,21 – 0,92 ± 0.13) provavelmente devido ao fato da QTP ser carreada pela LNC e não estar disponível para interagir com transportadores. Conclusão: Considerando todos os resultados sugere-se que as LNC do tipo III carreiam a QTP através da circulação sistêmica até o parênquima cerebral. / Introduction: Blood-brain barrier (BBB) hinders the delivery of therapeutics to central nervous system due to the endothelial cells tight junctions, which restrict paracellular transport of substances, and the expression of influx and efflux transporters, which modulate drugs access to the brain. Lipid-core nanocapsules (LNC) have been proposed as drug carriers to improve brain delivery by modulating drug pharmacokinetics (PK). However, little in know about this modulation process and it is not clear whether the LCN carry the drug through the BBB or increase free drug penetration due to changes in the barrier permeability. Objective: The work aimed to investigate the alterations in the model drug quetiapine (QTP) plasma PK and brain penetration following nanoencapsulation into LNC (QLNC) using microdialysis. Methods: QLNC (1 mg.mL-1) were obtained by nanoprecipitation and presented small particle size (143 ± 6 nm), low polidispersion index (PI < 0.1), high incorporation efficiency (96%), negative zeta potential (–7.65 ± 0.815 mV) and acidic pH. TEM photomicrography showed spherically shaped particles and absence of aggregation. Animal studies approved by CEUA/UFRGS. Total plasma and free plasma and brain concentrations, last two determined by microdialysis, were analyzed after QLNC (5 mg/kg) and free drug (FQ – 5 and 10 mg/gk) i.v. dosing to Wistar rats alone or following probenecid (PB), an influx transporter inhibitor, i.v. administration (30 mg/kg). Drug was quantified in all matrices by validate LC/UV methods. Total brain and liver concentration after FQ and QLNC dosing were investigated in tissues homogenate. Furthermore, QTP free fraction (fu) in plasma and erythrocyte penetration were determined. Results: QTP presented linear PK in the dose range investigated and is substrate to influx transporters at the BBB. Differences observed on QTP fu up to 2 h after QLNC dosing indicate a drug slow release in the blood stream loaded into the LNC type III nanocarrier for this period of time. The LNC did not altered QTP erythrocytes partition coefficient. Total brain and liver concentrations were increased after QLNC dosing but free brain concentrations were not altered in comparison with FQ dosing. After PB dosing, QTP brain penetration was reduced from 1.55 ± 0.17 to 0.94 ± 0.15 when FQ was administered but the inhibition of influx transporters had no effect on QLNC brain penetration (0.88 ± 0.21 to 0.92 ± 0.13) probably because QTP is loaded into the LNC and not available to interact with transporters. Conclusions: Taking together these results suggested that LNC type III carries QTP in the blood stream and delivers the drug to the brain.

Alzheimer's disease (AD) is the leading cause of dementia. Amyloid plaques in the brain remain a pathological feature of AD. These plaques are primarily composed of amyloid β-protein (Aβ). It has been postulated that glycogen synthase kinase-3β (GSK3β) activity might exert a central role in the development of AD. GSK3β activity has been implicated in tau phosphorylation, APP processing, Aβ production and neurodegeneration. Quetiapine is frequently used to treat psychoses in AD patients at the late stage and has inhibitory effects on GSK3β activity in mouse brains after acute/subchronic treatment. Therefore, the proposed hypothesis is that chronic quetiapine administration after amyloid plaque onset reduces AD like pathology and alleviates AD like behaviours in APP/PS1 transgenic mice by inhibiting GSK3β activity. APP/PS1 transgenic mice were treated with quetiapine (2.5, 5 mg/kg/day) in drinking water starting from 3.5 months of age, for a period of 8 months. One week after behaviour testing, mice were sacrificed at 12 months of age. Half of the hemispheres were rapidly frozen for immunoblot and ELISA analyses and the other half were fixed with 4% paraformaldehyde for histological analyses. Quetiapine treatment reduced amyloid plaques formation in the cortex and hippocampus of AD mice. It also improved the behavioural deficits in these mice, including attenuating impaired memory and anxiety-like phenotypes. In addition, chronic quetiapine administration inhibited GSK3β, which resulted in reduced production of Aβ in cortices and hippocampi of transgenic mice. Quetiapine treatment also significantly decreased the activation of astrocytes and attenuated synapse integrity impairment in transgenic mice. These findings suggest that early application of quetiapine can alleviate memory deficits and pathological changes in the APP/PS1 transgenic mouse model of AD, and further support that modulation of GSK3β activity by quetiapine may be a therapeutic option for AD.

Alzheimer's disease (AD) is the leading cause of dementia. Amyloid plaques in the brain remain a pathological feature of AD. These plaques are primarily composed of amyloid β-protein (Aβ). It has been postulated that glycogen synthase kinase-3β (GSK3β) activity might exert a central role in the development of AD. GSK3β activity has been implicated in tau phosphorylation, APP processing, Aβ production and neurodegeneration. Quetiapine is frequently used to treat psychoses in AD patients at the late stage and has inhibitory effects on GSK3β activity in mouse brains after acute/subchronic treatment. Therefore, the proposed hypothesis is that chronic quetiapine administration after amyloid plaque onset reduces AD like pathology and alleviates AD like behaviours in APP/PS1 transgenic mice by inhibiting GSK3β activity. APP/PS1 transgenic mice were treated with quetiapine (2.5, 5 mg/kg/day) in drinking water starting from 3.5 months of age, for a period of 8 months. One week after behaviour testing, mice were sacrificed at 12 months of age. Half of the hemispheres were rapidly frozen for immunoblot and ELISA analyses and the other half were fixed with 4% paraformaldehyde for histological analyses. Quetiapine treatment reduced amyloid plaques formation in the cortex and hippocampus of AD mice. It also improved the behavioural deficits in these mice, including attenuating impaired memory and anxiety-like phenotypes. In addition, chronic quetiapine administration inhibited GSK3β, which resulted in reduced production of Aβ in cortices and hippocampi of transgenic mice. Quetiapine treatment also significantly decreased the activation of astrocytes and attenuated synapse integrity impairment in transgenic mice. These findings suggest that early application of quetiapine can alleviate memory deficits and pathological changes in the APP/PS1 transgenic mouse model of AD, and further support that modulation of GSK3β activity by quetiapine may be a therapeutic option for AD.

Introdução: A barreira hematoencefálica limita a penetração de compostos farmacologicamente ativos para o cérebro devido à presença de zônulas de oclusão no endotélio cerebral e a expressão de transportadores de influxo e efluxo que modulam o acesso de fármacos para o parênquima cerebral. Nanocápsulas de núcleo lipídico (LNC) tem sido estudadas como carreadores de fármacos para o tecido cerebral devido à capacidade de modulação da farmacocinética desses compostos. Entretanto, ainda pouco se sabe sobre os processos envolvidos nas alterações farmacocinéticas e na distribuição tecidual promovidas por esses transportadores. Objetivo: Pretendeu-se investigar as alterações na farmacocinética plasmática e penetração cerebral da quetiapina (QTP) nanoencapsulada em ratos Wistar. Materiais e Métodos: QLNC (1mg/mL) foram obtidas através da metodologia de nanoprecipitação e apresentaram reduzido tamanho de partícula (143 ± 6 nm), baixo indicie de polidispersão (PI < 0.1), alta eficiência de encapsulação (96%), potencial zeta negativo (-7.65 ± 0.815 mV) e pH ácido. QLNC quando visualizadas por MET apresentaram tamanho esférico, homogêneo com ausência de agregados. Os estudos in vivo desse trabalho foram aprovados pelo CEUA/UFRGS. Análise do plasma total e a utilização da microdiálise para determinação das concentrações plasmáticas e cerebrais livres foram realizadas após administração intravenosa da formulação de nanocápsulas de QTP (5 mg /kg ) (QLCN) ou do fármaco em solução (FQ) (5 mg /kg e 10 mg /kg) na presença e na ausência de 30 mg /kg de probenecida (PB), um inibidor de transportadores de membrana. Métodos validados foram utilizados para a quantificação do fármaco em diferentes matrizes. As concentrações cerebral e hepática totais foram investigadas através da técnica de homogeneizado de tecido. Além disso, a fração livre no plasma (fu) e a penetração nos eritrócitos também foi realizada. Resultados: QTP apresentou farmacocinética linear na faixa de doses investigadas, é um substrato para transportadores de efluxo na BHE. Diferenças foram observadas na fu da QTP até 2 h após administração de QLNC indicando que LNC do tipo III promove uma liberação sustentada do fármaco do carreador. QLNC não foi capaz de alterar o coeficiente de partição nos eritrócitos determinado in vitro. As concentrações cerebrais e hepáticas totais foram aumentadas após administração da formulação de nanocápsulas, porém, as concentrações cerebrais livres não foram alteradas em comparação com o QTP em solução. Após administração de PB o fator de penetração da QTP livre no cérebro foi reduzido de 1,55 ± 0.17 para 0,94 ± 0,15. Porém, essa inibição pela probenecida não teve efeito na penetração cerebral de QLNC (0,88 ± 0,21 – 0,92 ± 0.13) provavelmente devido ao fato da QTP ser carreada pela LNC e não estar disponível para interagir com transportadores. Conclusão: Considerando todos os resultados sugere-se que as LNC do tipo III carreiam a QTP através da circulação sistêmica até o parênquima cerebral. / Introduction: Blood-brain barrier (BBB) hinders the delivery of therapeutics to central nervous system due to the endothelial cells tight junctions, which restrict paracellular transport of substances, and the expression of influx and efflux transporters, which modulate drugs access to the brain. Lipid-core nanocapsules (LNC) have been proposed as drug carriers to improve brain delivery by modulating drug pharmacokinetics (PK). However, little in know about this modulation process and it is not clear whether the LCN carry the drug through the BBB or increase free drug penetration due to changes in the barrier permeability. Objective: The work aimed to investigate the alterations in the model drug quetiapine (QTP) plasma PK and brain penetration following nanoencapsulation into LNC (QLNC) using microdialysis. Methods: QLNC (1 mg.mL-1) were obtained by nanoprecipitation and presented small particle size (143 ± 6 nm), low polidispersion index (PI < 0.1), high incorporation efficiency (96%), negative zeta potential (–7.65 ± 0.815 mV) and acidic pH. TEM photomicrography showed spherically shaped particles and absence of aggregation. Animal studies approved by CEUA/UFRGS. Total plasma and free plasma and brain concentrations, last two determined by microdialysis, were analyzed after QLNC (5 mg/kg) and free drug (FQ – 5 and 10 mg/gk) i.v. dosing to Wistar rats alone or following probenecid (PB), an influx transporter inhibitor, i.v. administration (30 mg/kg). Drug was quantified in all matrices by validate LC/UV methods. Total brain and liver concentration after FQ and QLNC dosing were investigated in tissues homogenate. Furthermore, QTP free fraction (fu) in plasma and erythrocyte penetration were determined. Results: QTP presented linear PK in the dose range investigated and is substrate to influx transporters at the BBB. Differences observed on QTP fu up to 2 h after QLNC dosing indicate a drug slow release in the blood stream loaded into the LNC type III nanocarrier for this period of time. The LNC did not altered QTP erythrocytes partition coefficient. Total brain and liver concentrations were increased after QLNC dosing but free brain concentrations were not altered in comparison with FQ dosing. After PB dosing, QTP brain penetration was reduced from 1.55 ± 0.17 to 0.94 ± 0.15 when FQ was administered but the inhibition of influx transporters had no effect on QLNC brain penetration (0.88 ± 0.21 to 0.92 ± 0.13) probably because QTP is loaded into the LNC and not available to interact with transporters. Conclusions: Taking together these results suggested that LNC type III carries QTP in the blood stream and delivers the drug to the brain.