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Development of solution NMR method for observation and analysis of proteins inside cells / 核磁気共鳴法による細胞内タンパク質の観測及び手法開発Murayama, Shuuhei 23 March 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19003号 / 工博第4045号 / 新制||工||1622(附属図書館) / 31954 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 白川 昌宏, 教授 佐藤 啓文, 教授 梶 弘典 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
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Establishing advanced deep learning models for predicting drug side effects / 薬物の副作用を予測するための高度なディープラーニングモデルの構築NGUYEN, DUC ANH 23 March 2023 (has links)
京都大学 / 新制・課程博士 / 博士(薬科学) / 甲第24559号 / 薬科博第176号 / 新制||薬科||19(附属図書館) / 京都大学大学院薬学研究科医薬創成情報科学専攻 / (主査)教授 馬見塚 拓, 教授 山下 富義, 教授 金子 周司 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM
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資料採礦之實務—心血管之交互作用與用藥分析蘇芷凡, Su, Tzu-Fan Unknown Date (has links)
當越來越多的藥物被發展出來進而治療人類的疾病,人們使用藥物時只知道該藥物對疾病的療效,卻忽略了其中可能隱藏的危機,不只是西藥,連中藥也隱藏相當大的危機。雖然國內有藥品管制局進行藥物交互作用的控管,但是藥物交互作用真的被有效控管嗎?成效又如何呢?有鑑於此,這成為大家都想知道的問題。
利用健保資料庫中龐大的門診資料,嘗試推估國人藥物交互作用的情形,由國人十大死因中得知,其中尤以慢性病病患的情形更為嚴重,例如:惡性腫瘤、腦血管疾病、心臟疾病、糖尿病、肝病和高血壓,本次研究以心血管病患為討論主體,試瞭解在長期服用心血管藥物時,醫生在已知病患病情之下卻無法避免藥物交互作用的情形為何,利用資料採礦的方法,找出可能造成交互作用發生的原因、族群,進而去提醒醫療機構避免其發生。
研究發現,心血管疾病病患分為一些併發症族群,如:心臟病、心血管疾病糖尿病、關節炎、消化潰瘍,從這些病患用藥中發現許多交互作用的用藥與其併發症也許多相關。高血壓疾病病患大多以強心劑、利尿劑為主的交互作用,心血管疾病併發糖尿病病患大多以口服降血糖為主的交互作用,心血管疾病併發關節炎病患大多以解熱鎮痛劑為主的交互作用,而心血管疾病併發消化潰瘍病患大多以制酸劑為主的交互作用。
健保局應當面對且對交互作用之高危險族群作一共同用藥規則,將用藥危機降到最低,讓心血管病患在治療的過程中,得以享有良好的醫療品質,亦不造成藥物濫用、浪費之情形。 / As more medicines are being developed to cope with diseases, most of the users think of the therapeutic effect of the medicine without thinking of the risk that might have associated with drug interactions. The risk of drug interactions could have set chemical reactions thereby causing drug side effects. Although the National Bureau of Controlled Drugs has set a procedure for controlling drug interactions, the issue of validity and efficiency remains an open question.
The trend of people contracting chronic diseases is on the rise, one of which is cardiovascular. The attempt of this paper is to observe for the effect of drug interactions if any for the long term usage of the cardiovascular medications under the supervision of the doctors. We adopt data mining techniques to single out the probable variable causes in triggering negative effect of drug interactions and presented them to related medical personnel so that a tightening measure is adopted when administered the medications. The data used in this research comes from the National Health Insurance Research Database.
Our research findings have reviewed that cardiovascular disease patients suffering from the complications, such as diabetes, arthritis, peptic ulcer and hear disease are highly related to the drug interactions. Heart disease patients are at risk of cardiac stimultants and diuretics. Diabetic’s patients taking the Sulfonylureas suffer from its interactions. And arthritis patients are at risk of having the side effects of taking Aspirin.
Bureau of National Health Insurance should set a standard procedure in monitoring the prescription given by the medical personnel in an effort to reduce the risk of drug interactions and set off the stage of quality medical treatment to keep off the abuse of drug usages.
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Étude pharmacogénomique de la warfarine et de l'activité physiqueRouleau-Mailloux, Étienne 04 1900 (has links)
La warfarine est un médicament anticoagulant possédant un faible index thérapeutique et une grande variabilité intra et interindividuelle dans la réponse au traitement. Les facteurs déterminants de la réponse à la warfarine ne sont pas tous connus et la présente étude vise à tester l'hypothèse que la pratique régulière d’activité physique puisse y être associée. Nous avons évalué si l’activité physique, mesurée à l’aide de 2 questionnaires différents, était associée à la dose de warfarine et au pourcentage de temps passé à l'intérieur de l'intervalle thérapeutique ciblé (time in therapeutic range : TTR).
L’étude a été menée chez les 1064 participants de la Cohorte warfarine de l’Institut de Cardiologie de Montréal (ICM) et chez 618 utilisateurs de warfarine issus de la Biobanque de l’ICM.
Nous avons trouvé que, dans les deux cohortes, les patients actifs nécessitaient une dose hebdomadaire moyenne plus élevée que les patients inactifs. L’association perdurait lorsque le modèle statistique était ajusté pour différentes variables connues pour influencer la réponse à la warfarine, telles que le génotype aux gènes CYP2C9 et VKORC1, l’âge, la taille, le poids, et l’INR ciblé. L’INR ciblé est décidé par le médecin et il correspond généralement à 2,0 – 3,0 ou 2,5 – 3,5. Les patients de la Cohorte warfarine avaient aussi plus de chances d’avoir un TTR inférieur à 60%, donc d’être moins stables.
La pratique régulière d’activité physique est donc un facteur déterminant de la dose thérapeutique de warfarine et la pratique d'activité physique intensive est associée à un TTR plus faible. / Warfarin is an oral anticoagulant agent with a narrow therapeutic index. Dosing of warfarin is highly variable among patients and it may also vary in time for the same patient. All factors influencing warfarin response are not known and this study aims to elucidate if regular physical activity is one important factor. We evaluated whether warfarin dosage and the time in therapeutic range (TTR) were associated with RPA. RPA was measured via 2 different questionnaires.
The study was conducted by using 1,064 patients in the Quebec Warfarin Cohort (QWC) and 618 patients from the Genetic-Hospital Cohort. Both cohorts are hosted at the Montreal Heart Institute.
In both cohorts, we found that active patients required higher weekly doses of warfarin than inactive patients. The association was maintained when the model was adjusted for variables known to influence warfarin response, i.e. CYP2C9 and VKORC1 genotypes, age, height, weight and targeted INR. The targeted INR is fixed by the physicist and is usually between 2.0 and 3.0 or between 2.5 or 3.5. Active patients from the QWC were more susceptible to have a TTR inferior to 60%, i.e. to be unstable.
RPA influences warfarin response and intensive RPA is associated with a greater instability in treatment response.
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An Exploratory Analysis of Twitter Keyword-Hashtag Networks and Knowledge Discovery ApplicationsHamed, Ahmed A 01 January 2014 (has links)
The emergence of social media has impacted the way people think, communicate, behave, learn, and conduct research. In recent years, a large number of studies have analyzed and modeled this social phenomena. Driven by commercial and social interests, social media has become an attractive subject for researchers. Accordingly, new models, algorithms, and applications to address specific domains and solve distinct problems have erupted. In this thesis, we propose a novel network model and a path mining algorithm called HashnetMiner to discover implicit knowledge that is not easily exposed using other network models. Our experiments using HashnetMiner have demonstrated anecdotal evidence of drug-drug interactions when applied to a drug reaction context.
The proposed research comprises three parts built upon the common theme of utilizing hashtags in tweets.
1 Digital Recruitment on Twitter. We build an expert system shell for two different studies: (1) a nicotine patch study where the system reads streams of tweets in real time and decides whether to recruit the senders to participate in the study, and (2) an environmental health study where the system identifies individuals who can participate in a survey using Twitter.
2 Does Social Media Big Data Make the World Smaller? This work provides an exploratory analysis of large-scale keyword-hashtag networks (K-H) generated from Twitter. We use two different measures, (1) the number of vertices that connect any two keywords, and (2) the eccentricity of keyword vertices, a well-known centrality and shortest path measure. Our analysis shows that K-H networks conform to the phenomenon of the shrinking world and expose hidden paths among concepts.
3 We pose the following biomedical web science question: Can patterns identified in Twitter hashtags provide clinicians with a powerful tool to extrapolate a new medical therapies and/or drugs? We present a systematic network mining method HashnetMiner, that operates on networks of medical concepts and hashtags. To the best of our knowledge, this is the first effort to present Biomedical Web Science models and algorithms that address such a question by means of data mining and knowledge discovery using hashtag-based networks.
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Développement et validation de méthodes de dosage du midazolam, un marqueur de l'activité des CYP3A, et de la fexofénadine, un substrat de la glycoprotéine P, dans les milieux biologiquesStepanova, Tatiana January 2009 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
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Rôles des polymorphismes génétiques dans la détermination de la dose individuelle de la warfarine chez les patients traités avec de l’amiodaroneBahroun, Imen 05 1900 (has links)
Introduction : Bien que la pratique de l’usage de la warfarine se soit améliorée au cours de la dernière décennie, aucune recommandation claire basée sur le dosage de l’amiodarone n’a été jusqu’à maintenant standardisée, ce qui représente un grand obstacle pour les cliniciens. La warfarine a un index thérapeutique étroit nécessitant un suivi régulier et un ajustement individuel de la posologie, ceci afin de déterminer la dose thérapeutique, tout en prévenant les effets secondaires qui pourraient être fatals dans certains cas. La variabilité interindividuelle de la réponse à la warfarine dépend de plusieurs facteurs, dont l’âge, le sexe, le poids, l’alimentation et l’interaction médicamenteuse, mais ceux-ci n’expliquent que partiellement les différences de sensibilité à la warfarine. Les polymorphismes des gènes CYP2C9 et VKORC1 jouent un rôle important dans la réponse à la warfarine et expliquent jusqu’à 50% de la variabilité des doses. L’utilisation d’antiarythmiques telle l’amiodarone peut accentuer considérablement l’effet de la warfarine et nécessite généralement une diminution de 30 à 50% de la dose de la warfarine. Aucune étude à ce jour n’a tenté de déterminer l’utilité du génotypage des polymorphismes des gènes CYP2C9 et VKORC1 chez les patients sous traitement combiné de warfarine et amiodarone.
Objectif : Notre étude a pour objectif tout d’abord de déterminer si des facteurs génétiques influencent la première dose de stabilisation de la warfarine chez les patients en FA après l’introduction de l’amiodarone. Nous allons également tenter de confirmer l’association préalablement rapportée entre les facteurs génétiques et la première dose de stabilisation de warfarine dans notre population à l’étude.
Méthodes : Un devis de cohorte rétrospective de patients qui fréquentaient la clinique d'anticoagulothérapie de l’Institut de cardiologie de Montréal entre le 1er janvier 2007 et le 29 février 2008 pour l’ajustement de leur dose selon les mesures d'INR. Au total, 1615 patients ont été recrutés pour participer à cette étude de recherche. Les critères de sélection des patients étaient les patients avec fibrillation auriculaire ou flutter, ayant un ECG documenté avec l'un de ces deux diagnostics et âgé de moins de 67 ans, en raison d’une moindre comorbidité. Les patients souffrant d’insuffisance hépatique chronique ont été écartés de l’étude. Tous les patients devaient signer un consentement éclairé pour leur participation au projet et échantillon de sang a été pri pour les tests génétiques. La collecte des données a été effectuée à partir du dossier médical du patient de l’Institut de cardiologie de Montréal. Un formulaire de collecte de données a été conçu à cet effet et les données ont ensuite été saisies dans une base de données SQL programmée par un informaticien expert dans ce domaine. La validation des données a été effectuée en plusieurs étapes pour minimiser les erreurs. Les analyses statistiques utilisant des tests de régression ont été effectuées pour déterminer l’association des variants génétiques avec la première dose de warfarine.
Résultats : Nous avons identifié une association entre les polymorphismes des gènes CYP2C9 et VKORC1 et la dose de la warfarine. Les polymorphismes génétiques expliquent jusqu’à 42% de la variabilité de dose de la warfarine. Nous avons également démontré que certains polymorphismes génétiques expliquent la réduction de la dose de warfarine lorsque l’amiodarone est ajoutée à la warfarine.
Conclusion : Les travaux effectués dans le cadre de ce mémoire ont permis de démontrer l’implication des gènes CYP2C9 et VKORC1 dans la réponse au traitement avec la warfarine et l’amiodarone. Les résultats obtenus permettent d’établir un profil personnalisé pour réduire les risques de toxicité, en permettant un dosage plus précis de la warfarine pour assurer un meilleur suivi des patients. Dans le futur, d’autres polymorphismes génétiques dans ces gènes pourraient être évalués pour optimiser davantage la personnalisation du traitement. / Background: Although the practice of the use of warfarin has improved during the last decade, no clear recommendation based on the determination of Amiodarone has been standardized until now, which is a major obstacle for clinicians. Warfarin has a narrow therapeutic index requiring regular monitoring and an individual dose ajustement, to this determines the therapeutic dose, while avoiding the side effects that could be fatal in some cases. The interindividual variability to the Warfarin depends on several factoring age, sex, weight, food and drug interactions but they only partially explain the differences in sensitivity to Warfarin. The polymorphisms of the genes CYP2C9 and VKORC1 play an important role in the response to the Warfarine and explain 50% of the variability of doses.The use of antiarrhythmic Amiodarone can greatly enhancethe effect of Warfain and generally requires a reduction of 30-50% of the dose of Warfarin. No study to date has attempted to determine the utility of genotyping polymorphisms of CYP2C9 and VKORC1 in patients on combination therapy of Warfarin and Amiodarone.
Objectives: Our study aims to first determine if genetic factors influence the first dose stabilization of Warfarin in patients with AF after the introduction of Amiodarone. We will also attempt to confirm the previously reported between genetic association and the first dose of Warfarin stabilization in our study population.
Methods: A retrospective cohort of all patients who frequent the clinic Warfarin of Montreal Heart Institute between 01/01/2007 and 02/30/2008 for the adjustment of their INR. The total of 1615 patients were recruited. The criteria for selection were patients with atrial fibrillation or flutter, with ECG documented with one of these tow diagnostic and younger than 67 years because of reduced morbidity. Patients with chronic liver disease were excluded from the study. All patients had to sign an informed consent for their participation in the project to which they contributed 15 ml of blood for genetic testing. Data collection was conducted from the patient's medical record of the Montreal Heart Institute. A data collection form was designed for this purpose and the data were then entered into a SQL database programmed by a computer expert in this field. Data validation was performed in several steps to minimize errors. Statistical analysis using regression tests were conducted to determine the association of genetic variants with the first dose of Warfarin.
Results: We identified an association between polymorphisms of the genes CYP2C9 and VKORC1 and warfarin dose. Genetic polymorphisms to explain 42% of the variability in dose of Warfarin. We also demonstrated that genetic polymorphisms explain the reduction in the dose of Warfarin when Amiodarone is added to Warfarin.
Conclusion: Our Work in the context of this thesis have shown the involvement of CYP2C9 and VKORC1 genes in response to treatment with Warfarin and Amiodarone. The results are used to create a personalized profile to reduce the risk of toxicity, enabling a more accurate dosing of warfarin for better monitoring of patients. In the future, other genetic polymorphisms in these genes could be evaluated to optimize the value of personalised therapy.
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Contribution pulmonaire à l’élimination systémique du propofol chez le patient sous anesthésie généraleAl-Hage Ali, Nadine 10 1900 (has links)
Diverses études cliniques ont démontré l’existence d’un métabolisme extrahépatique du propofol. Le lieu exact de ce métabolisme n’est pas encore complètement élucidé chez l’homme. Des données chez l’animal suggèreraient que le poumon pourrait contribuer à la clairance totale du propofol. Le présent projet vise à investiguer la contribution pulmonaire à l’élimination systémique du propofol chez des patients sous anesthésie générale.
Quatorze patients de type ASA I ou II, âgés entre 35 et 70 ans, pour lesquels une chirurgie cardiaque de routine était prévue, ont été inclus dans la présente étude. Le protocole a été préalablement approuvé par le comité d’éthique et les patients ont tous donné par écrit leur consentement éclairé. Le recrutement des patients a eu lieu à l’hôpital Royal Victoria.
Le propofol a été administré en induction sous forme de bolus intraveineux, suivi d’une perfusion continue de 50 g/kg/min. Chez un même patient, des prélèvements sanguins pré- et post pulmonaires ont été pris simultanément de l’artère radiale et de l’artère pulmonaire, sous des conditions de ventilation contrôlée ou apnéiques, dans le but de mesurer les concentrations plasmatiques du propofol.
Le gradient artério-veineux a été évalué à l’état d’équilibre afin de déterminer la contribution du poumon à l’élimination totale de propofol. Nous n’avons pas pu démontrer l’existence d’une extraction pulmonaire du propofol chez l’humain. Ceci pourrait être dû à plusieurs facteurs méthodologiques. / Several clinical studies have demonstrated the existence of propofol extrahepatic metabolism. The exact nature and site of this metabolism is not fully elucidated in man, however, the lung may possibly contribute to propofol total clearance as suggested by animal findings.
In the present study, pulmonary contribution to total body elimination of propofol was investigated in patients during cardio-surgical anesthesia. Following informed consent and research ethic board approval, fourteen patients-ASA category I or II, between 35 and 70 years of age and scheduled for routine cardiac surgery were included in the present study. Patients were recruited at Royal-Victoria Hospital. At induction, propofol was administered as an intravenous bolus followed by a continuous infusion rate of 50 g/kg/min.
Arterial and mixed-venous blood samples were drawn simultaneously from the radial artery and pulmonary artery catheters from patients under controlled ventilation or apneic conditions, for measurement of plasma propofol concentrations. Arterio-venous gradient was assessed under steady-state conditions to evaluate a potential contribution of the lung to the overall elimination of propofol. No statistically significant differences were found between both sampling sites, either under controlled ventilation or after a short period of apnea.
We were unable to demonstrate the existence of propofol pulmonary extraction in the lungs in
humans. This might be explained by methodological factors
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Estudo in vitro do perfil metabólico do agente antitumoral piplartina frente às enzimas do citocromo P450 e predição de parâmetros farmacocinéticos / Metabolic profile of the antitumor agent piplartine by Cytochrome P450 enzymes, in vitro study and prediction of pharmacokinetic parametersMoreira, Fernanda de Lima 21 February 2017 (has links)
A piplartina (PPT) ou piperlongumine é um produto natural da classe dos alcaloides encontrada em espécies da família Pipereaceae. Devido a sua alta potência e seletividade na inibição de diversas linhagens de células tumorais, a PPT têm sido investigada como um potencial candidato à fármaco. Neste contexto, estudos relacionados à sua toxicidade e segurança devem ser realizados, incluindo a determinação do papel das enzimas do Citocromo P450 (CYP450) sobre o metabolismo da PPT. Esta família de enzimas é responsável pela biotransformação de cerca de 75% dos fármacos presentes no mercado. Os estudos pré-clínicos que visam avaliar o metabolismo podem ser realizados empregando modelos in vitro como uma ferramenta para predição de características farmacocinéticas in vivo. Assim, o presente estudo teve como objetivo a avaliação do perfil metabólico da PPT frente as enzimas do CYP450 empregando-se estudos in vitro com microssomas hepáticos humanos (HLM) e a posterior predição de parâmetros farmacocinéticos. Estes estudos incluíram a determinação de parâmetros enzimáticos, estudos de inibição da PPT sobre as principais isoformas do CYP450, elucidação estrutural de metabólitos gerados com a reação de metabolismo e, finalmente, estudos de fenotipagem enzimática. A metodologia geral de estudo de metabolismo in vitro envolveu o uso de técnicas cromatográficas acopladas a diversos detectores/analisadores, tais como arranjo de diodos, espectrometria de massa e ressonância magnética nuclear. O metabolismo foi avaliado pela medida da taxa de desaparecimento da PPT do meio microssomal. Após validação da metodologia para quantificação da PPT e determinação das condições de velocidade inicial de reação, um perfil sigmoidal foi obtido, indicando o metabolismo da PPT por enzimas contendo múltiplos sítios ativos e/ou catálise por diversas enzimas concomitantemente. Os parâmetros cinéticos calculados foram Vmax = 5,5 ± 0,5 nmol mg proteína-1 min-1, S50 = 127,70 ?mol L-1 e Coeficiente de Hill (h) = 3. O clearance intrínseco obtido foi de 22,68 ?L min -1 mg -1. A fração não ligada às proteínas plasmáticas e microssomais foi de 0,07 e 0,76, respectivamente. O clearance in vivo predito foi de 19,79 mL min -1 kg -1, o clearance hepático de 1,89 mL min -1 kg -1 e extração hepática de 0,09. Dentre quatro isoformas avaliadas, CYP3A, CYP2C9, CYP2D6 e CYP1A2, a PPT demonstrou um potencial em causar interação produto natural-medicamento apenas sobre a CYP1A2. A PPT é um inibidor competitivo dose-dependente da CYP1A2, apresentando um valor de Ki de 1,5 ?mol L-1. A razão [I]/Ki obtida de 9,1 prediz uma interação relevante in vivo. Além disso, a PPT apresentou uma inibição tempo-dependente sobre a CYP1A2 com valores de KI de 8 ?mol L-1 e kinact de 0,014 min-1. A inibição dose-, ii NADPH- e tempo-dependente confirmam uma inibição baseada no mecanismo em que o modo pelo qual a PPT liga-se à enzima é irreversível. Baseado nos dados obtidos pelas análises por espectrometria de massa e ressonância magnética nuclear, quatro metabólitos gerados após metabolismo da PPT com HLM tiveram suas estruturas propostas. Assim, foram caracterizados os metabólitos M1 (produto de uma desmetilação na posição meta do anel 3,4,5-trimetoxicinâmico), M2 (produzido por uma epoxidação entre o C3 e C4 do anel lactâmico), M3 (gerado através de uma oxidação no C5 do anel lactâmico) e, finalmente, M4 (produto de uma reação transdiidrodiol entre C3 e C4). O metabólito M4 é formado tardiamente (após 40 min de reação) e provavelmente é um metabólito secundário produzido a partir de M2 através de uma reação trans-diidrodiol. O estudo de fenotipagem demonstrou que as principais isoformas que contribuem para o metabolismo da PPT são a CYP1A2 (formação de M1) e a CYP3A4 (formação de M2 e M3). O emprego das isoformas recombinantes demonstrou a formação de M4 a partir da catálise por diversas isoformas, CYP2C19, CYP2C8, CYP2D6, CYP2B6 e CYP2E1. Portanto, o perfil metabólico do candidato a agente antitumoral PPT frente às enzimas do CYP450 foi demonstrado neste trabalho, proporcionando aspectos relacionados à segurança e eficácia desta substância. Os dados apresentados certamente servirão como guia em estudos clínicos futuros / Piplartine (PPT) or Piperlongumine is a naturally occurring alkaloid found in species of Pipereaceae family. Due its high potency and selectivity of inhibition of several cancer cell lines, PPT has been investigated as a potential drug candidate. In this context, studies related with toxicity and safety should be performed, including the role of the Cytochrome P450 (CYP450) enzymes in PPT metabolism. This family of enzymes is responsible for the biotransformation of 75% of the drugs in the market. The preclinical studies that aim to evaluate the drug metabolism can be performed by employing in vitro models as a tool for prediction of in vivo pharmacokinetic characteristics. Therefore, the aim of this work was to evaluate the metabolic profile of PPT after metabolism by CYP450 enzymes employing in vitro studies with human liver microsomes (HLM) and the ensuing prediction of pharmacokinetic parameters. These studies embraced the kinetic parameters determination, inhibition ability of PPT over the most important CYP450 isoforms, structural elucidation of the produced metabolites after metabolism reaction and, finally, the enzymatic phenotyping study. The general procedure for in vitro metabolism studies consisted of the use of chromatographic techniques coupled to different detectors/analyzers, such as diode array, mass spectrometry and nuclear magnetic resonance. The metabolism was evaluated measuring the rate of disappearance of the PPT from de microsomal medium. After method validation for PPT quantification and determination of initial velocity conditions, the enzymatic kinetics with a sigmoidal profile indicating a metabolism of PPT by enzymes with multiple active sites and/or metabolism by multiple CYP450 enzymes was observed. The following parameters were calculated: Vmax = 5.5 ± 0.5 nmol/mg protein/min, S50 = 127.7 ?mol/L, and Hill coefficient of 3.0. The intrinsic clearance was 22.68 ?L min -1 mg -1. The unbound fraction of PPT on plasmatic and microsomal proteins was 0.07 and 0.76, respectively. The predicted in vivo clearance was 19.79 mL min -1 kg -1, the hepatic clearance was 1.89 mL min -1 kg -1 and the hepatic extraction was 0.09. Among 4 isoforms evaluated, CYP3A, CYP2C9, CYP2D6 and CYP1A2, a potential natural product-drug interaction for only CYP1A2 isoenzyme by PPT was observed. PPT showed to be a competitive and dosedependent inhibitor of CYP1A2, showing a Ki value of 1.5 ?mol L-1. The ratio [I]/Ki of 9.1 predicts an important in vivo interaction. Furthermore, a time-dependent inhibition of CYP1A2 with a KI of 8 ?mol L-1 and a kinact of 0.014 min-1 by PPT was demonstrated. The dose-, time- and NADPH-dependent inhibition confirms an inhibition based on mechanism through an irreversible bond. Based on results obtained from the mass spectrometry analysis and from the nuclear magnetic resonance analysis, four metabolites were identified and characterized. The metabolites characterized were: M1 (product of a demethylation in the 3,4,5-trimethoxyphenyl portion, M2 (derived from an epoxidation between C3 and C4 on the lactone ring), M3 (product of a simple oxidation on C5 of lactone ring), and finally M4 (derived from a dihydrodiol reaction between C3 and C4). The metabolite M4 is produced later (after 40 min of reaction) and probably is a secondary metabolite produced from M2 through a dihydrodiol reaction. The phenotyping study demonstrated that the main isoforms involved in PPT metabolism are CYP1A2 (production of M1) and CYP3A4 (production of M2 and M3). The recombinant isoforms study demonstrated that several isoforms (CYP2C19, CYP2C8, CYP2D6, CYP2B6 and CYP2E1) catalyze the production of M4. In summary, a wide view about the metabolism of the promising drug candidate PPT by CYP450 enzymes was accomplished. These results, certainly, will be a useful guide for further clinical studies of PPT
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Effects of Selected Natural Health Products on Drug Metabolism: Implications for PharmacovigilanceLiu, Rui 10 March 2011 (has links)
Seventeen Cree anti-diabetic herbal medicines and eight Traditional Chinese Medicines have been examined for their potential to cause interactions with drugs, which is considered as a major reason for adverse drug effects. Specifically, the effect of these natural health products was examined on major Phase I drug metabolism enzymes including cytochrome P450, human carboxylesterase-1 and flavin-containing monooxygenases. Several of these natural health products have the potential to cause adverse drug effect through the inhibition of major drug metabolism enzymes. The results indicated that 7 Cree medicines plant extracts inhibited CYP3A4 activity, and 3 of them have been proven to cause potent mechanism-based inactivation of CYP3A4. Seven of eight Traditional Chinese Medicines have been identified as strong CYP3A4 inhibitors; the ethanol extract of Goji has identified as a potent inhibitor for CYP2C9 and 2C19. Goji juice showed universal inhibitory effects on most of the tested enzymes except flavin-containing monooxygenases 3.
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