Objectifs : Définir les paramètres pharmacocinétiques du pantoprazole intraveineux en soins intensifs pédiatriques et déterminer l’influence qu’exercent sur ceux-ci les facteurs démographiques, le syndrome de réponse inflammatoire systémique (SRIS), la dysfonction hépatique et l’administration d’un inhibiteur du cytochrome (CYP) 2C19. Méthode : Cent cinquante-six concentrations plasmatiques de pantoprazole provenant d’une population de 20 patients (âgés de 10 jours à 16.4 ans) à risque ou atteints d’une hémorragie gastroduodénale de stress, ayant reçu des doses quotidiennes de pantoprazole de 19.9 à 140.6 mg/1.73m2, ont été analysées selon les méthodes non compartimentale et de modélisation non linéaire à effets mixtes. Résultats : Une clairance médiane (CL) de 0.14 L/h/kg, un volume apparent de distribution de 0.20 L/kg et une demi-vie d’élimination de 1.7 h ont été déterminés via l’approche non compartimentale. Le modèle populationnel à deux compartiments avec une infusion d’ordre zéro et une élimination d’ordre un représentait fidèlement la cinétique du pantoprazole. Le poids, le SRIS, la dysfonction hépatique et l’administration d’un inhibiteur du CYP2C19 constituaient les covariables significatives rendant compte de 75 % de la variabilité interindividuelle observée pour la CL. Seul le poids influençait significativement le volume central de distribution (Vc). Selon les estimations du modèle final, un enfant de cinq ans pesant 20 kg avait une CL de 5.28 L/h et un Vc de 2.22 L. La CL du pantoprazole augmentait selon l’âge et le poids tandis qu’elle diminuait respectivement de 62.3%, 65.8% et 50.5% en présence d’un SRIS, d’un inhibiteur du CYP2C19 ou d’une dysfonction hépatique. Conclusion : Ces résultats permettront de guider les cliniciens dans le choix d’une dose de charge et dans l’ajustement des posologies du pantoprazole en soins intensifs pédiatriques dépendamment de facteurs fréquemment rencontrés dans cette population. / Aims : To characterize the pharmacokinetics of intravenous pantoprazole in a paediatric intensive care population and to determine the influence of demographic factors, systemic inflammatory response syndrome (SIRS), hepatic dysfunction and concomitantly used cytochrome (CYP) 2C19 inhibitors on the drug’s pharmacokinetics. Methods : A total of 156 pantoprazole concentrations from 20 patients (aged from 10 days to 16.4 years) at risk for or with upper gastrointestinal bleeding, who received pantoprazole doses ranging from 19.9 to 140.6 mg/1.73m2/day, were analyzed using non compartmental and non linear mixed effects modelling (NONMEM) approaches. Results : The non compartmental results showed that median clearance (CL), apparent volume of distribution and elimination half-life were 0.14 L/h/kg, 0.20 L/kg and 1.7 h, respectively. The best structural model for pantoprazole was a two-compartment model with zero order infusion and first order elimination. Body weight, SIRS, age, hepatic dysfunction and presence of CYP2C19 inhibitors were the significant covariates affecting CL, accounting for 75% of interindividual variability. Only body weight significantly influenced central volume of distribution (Vc). In the final population model, the estimated CL and Vc were 5.28 L/h and 2.22 L, respectively, for a typical five year old child weighing 20 kg. Pantoprazole CL increased with weight and age whereas the presence of SIRS, CYP2C19 inhibitors and hepatic dysfunction, when present separately, significantly decreased pantoprazole CL by 62.3%, 65.8% and 50.5%, respectively. Conclusion : These results provide important information to physicians regarding selection of a starting dose and dosing regimen of pantoprazole for paediatric intensive care patients based on various factors frequently encountered in this population.

Die Beurteilung der Wirkung von Cariporide auf dieEreignis-Wahrscheinlichkeit eines Herzinfarktes oder des Todes imRahmen einer Bypass-Operation ist Gegenstand der Arbeit. DasNHE-Austauschersystem in der Herzmuskelzelle induziert den unterIschämie durch den intrazellulären Protonenüberschusshervorgerufenen Na(+)- und Ca(2+)-Einstrom. Cariporide ist einNHE-Inhibitor, der den unter Ischämie durch die Ca(2+)-Überladunginduzierten Herzmuskelzelltod verzögern soll. In einer kombinierten Phase-II/III-Studie (GUARDIAN, n=11590) war derEinfluss verschiedener intravenöser Dosen von Cariporide auf dieHäufigkeit von Herzinfarkt oder Tod in ACS/NQMI, PTCA undCABG-Patientenkollektiven untersucht worden. Nur die höchstdosierteCABG-Gruppe zeigte eine signifikante Reduktion der Ereignisrate um24,7% (p=0,027) gegenüber Placebo. Diese schwacheDosis-Wirkungs-Beziehung konnte durch eine pharmakokinetische undpharmakodynamische Populationsanalyse in eineKonzentrations-Wirkungs-Beziehung überführt werden. Zur Entwicklungdes Populationsmodells waren verschiedene Submodelle notwendig: 1. Modell für den Zeitverlauf der Ereignisrate: Durch Kombination zweier Weibull-Verteilungen ist es möglich, die beobachteten Daten als Überlebenszeitfunktion nach CABG zu beschreiben. Ein akutes, unmittelbar auf die CABG-Operation zurückzuführendes Risiko wird hier von einem chronischen Risiko unterschieden. 2. Pharmakokinetisches Modell: Ein multiexponentielles populationspharmakokinetisches Modell ist notwendig zur Beschreibung der PK nach iv-Applikation von Cariporide bei Probanden und Patienten. 3. Pharmakodynamisches Modell: Über ein empirisches logistisches Modell wird die Reduktion des akuten Risikos mit der mittleren Cariporide Plasmakonzentration unter der Bypass-Operation verknüpft. In einer Substudie der GUARDIAN-Hauptstudie konnte daspopulationspharmakokinetische Modell aus der früherenPhase-I-Entwicklung mit Probanden für die Patienten validiert werden.Die mit Hilfe der individüllen Dosierung, der demographischen Datenund dem Populationsmodell für die Periode mit dem höchsten Risikowährend der CABG-Operation vorhergesagten mittlerenPlasmakonzentrationen flossen in die Analyse derKonzentrations-Zeit-Abhängigkeit der Ereignis-Wahrscheinlichkeit ein. Eine untere Schwellenkonzentration (0,5mg/l), unterhalb der mitkeinem Effekt zu rechnen ist, wurde bestimmt. Die Daten erlaubten dieSchätzung des maximalen Effekts nur unzureichend. Die maximaleRisikoreduktion von 60% wurde mit einem Konfidenzintervall von29% bis 100% geschätzt. Unter Einsatz einer linearen Näherungdes Hill-Modells wurde eine obere Schwellenkonzentration bei 0,9mg/lbestimmt. Nur 37% aller Patienten der 80mg-Dosisgruppe erreichtenmittlere Konzentrationen oberhalb der unteren Schwellenkonzentration,in der 120mg-Dosisgruppe waren es immerhin schon 75% allerPatienten. Die Infusion von 120mg Cariporide über eine Stunde gefolgt voneiner Erhaltungsdosis von 20mg/h für weitere 47 Stunden sollte bei95% der Patienten während der CABG-Operation zu mittlerenKonzentrationen über der minimal effektiven Konzentration von0,5mg/l führen. Eine auf diese Weise mittels Simulationenoptimierte Dosierungsregel sollte während der CABG-Operation zu einemerhöhten Schutz der Patienten gegen die Folgen ischämischerEreignisse führen. Eine weitere Erhöhung der Erhaltungsdosis aufbis zu 40mg/h mit einer entsprechenden Anpassung der Initialdosissollte 95% der Patienten sogar über die bisher nur unsicher zubestimmende obere Grenzkonzentration von 0,9mg/l bringen. Solltenkeine dosislimitierenden Nebenwirkungen auftreten, kann dieseErhöhung sowohl der Initialdosis als auch der Erhaltungsdosis zueiner weiteren Verbesserung während der Risikoperiode führen undeinen weiteren potentiellen klinischen Vorteil für Cariporideerbringen. / Subject of this analysis is the assessment of the effect of cariporideon the event probability of a myocardial infarction (MI) or death inthe scope of a coronary artery bypass graft. Thesodium-hydrogen-exchange system (NHE) in the myocardial cell inducesthe sodium and calcium influx caused by an ischaemia induced hydrogenoverload. Cariporide is a NHE-inhibitor which is seen to be delayingthe necrosis of myocardial cells caused by the ischaemia inducedcalcium influx. The influence of different intravenous doses of cariporide on thefrequency of MI and death in ACS/NQMI, PTCA, and CABG patients hadbeen investigated in a combined phase II/III trial (GUARDIAN,n=11590). Only the highest dosed CABG-subgroup showed a significantreduction of the event-rate compared to placebo of 24.7% (p=0.027).This weak dose-effect-relationship could be translated into aconcentration-effect relationship by using a populationpharmacokinetic/pharmacodynamic (PK/PD) analysis. To develop thispopulation model a series of sub-models were established: 1) Model for the time-to-event progression: using a combination of two Weibull-distributions, it was possible to describe the observed data following the CABG procedure by means of a survival-function. An acute risk, likely to be related to the CABG-procedure could be discriminated from a chronic risk. 2) Pharmacokinetic model: a multi-exponential population PK model was necessary to describe the PK after iv-application of cariporide in volunteers as well patients. 3) Pharmacodynamic model: using an empirical logistic model the reduction of the acute risk was linked to the cariporide plasma-concentrations. In a sub-study of the GUARDIAN-main study, the population PK model ofthe phase I development in volunteers had been be validated. Usingthe individual dosing, the individual demographic information and thepopulation PK model mean concentrations were calculated for the periodof the highest risk during the CABG procedure. Those concentrationswere then introduced into the analysis of the concentration timedependency of the event probability. A lower threshold concentration (0.5mg/l) was estimated beneath thatno effect would be expected. The data permitted the estimation of themaximum effect only insufficiently. A maximum risk reduction of 60%was estimated with a confidence interval from 29% to 100%. Using thelinear approximation of the Hill-model an upper thresholdconcentration of 0.9mg/l could be determined. Mean concentrationsunder risk were reached above the lower threshold concentration inonly 37% of all patients in the 80mg dose group, whereas in the 120mgdose-group already 75% of the patients exceeded the lower thresholdconcentration. The infusion of 120mg cariporide for an hour followed by a maintenancedose of 20mg/h for further 47 hours should maintain in 95% of thepatients during the CABG-procedure mean concentrations above theminimal effective concentration of 0.5mg/l. A dose regimen optimisedin this sense by means of simulations should lead to an increasedprotection against ischemic events during and after theCABG-operation. A further increase of the maintenance dose up to40mg/h with a corresponding adaptation of the initial dose shouldshift at least 95% of the patients above the so far impreciseestimated upper threshold concentration of 0.9mg. If no dose limitingside-effects occur, this increase of both the initial dose and themaintenance dose may lead to a further improvement during the riskperiod and may result in a further potential clinical advantage forcariporide.

O carvedilol é um anti-hipertensivo disponível na clínica como mistura racêmica, sendo o (S)-(-)-carvedilol um bloqueador ? e ?1-adrenérgico e o (R)-(+)-carvedilol apenas ?1-adrenérgico. O carvedilol é metabolizado principalmente por glicuronidação e pelo CYP2D6 a hidroxifenilcarvedilol e pelo CYP2C9 a Odesmetilcarvedilol. O presente estudo avalia a disposição cinética e o metabolismo dos enantiômeros do carvedilol, hidroxifenilcarvedilol e O-desmetilcarvedilol em voluntários sadios não comedicados (n=13) ou comedicados com dose única oral de glibenclamida (5 mg) e metformina (500 mg) (n=13) e em pacientes portadores de diabetes mellitus tipo 2 (com bom controle glicêmico e em tratamento com glibenclamida 5 mg/8h e metformina 500 mg/8h; n=14), fenotipados como metabolizadores rápidos (n=26) ou lentos (n=1). Os voluntários e pacientes receberam dose única oral de 25 mg de carvedilol racêmico e amostras seriadas de sangue foram coletadas até 24h após a administração. A frequência cardíaca foi avaliada na situação de exercício isométrico com o handgrip durante 2 min a 30% da contratilidade voluntária máxima e durante o repouso. Os enantiômeros do carvedilol e metabólitos foram analisados em plasma por LC-MS/MS empregando coluna Chirobiotic® V. O método foi linear no intervalo de 0,05 a 100; 0,05 a 10 e 0,02 a 10 ng/mL para os enantiômeros do carvedilol, hidroxifenilcarvedilol e O-desmetilcarvedilol, os desvios do estudo de precisão e exatidão foram inferiores a 15% e não foi observado efeito matriz. A farmacocinética avaliada por modelo não compartimental mostra acúmulo plasmático dos enantiômeros (R)-(+)-carvedilol, (R)-(+)-O-desmetilcarvedilol e (R)-(+)- hidroxifenilcarvedilol. A disposição cinética e o metabolismo dos enantiômeros do carvedilol não diferem entre os grupos de voluntários não comedicados e comedicados com dose única oral de glibenclamida e metformina. No entanto, os valores de AUC de ambos os enantiômeros do metabólito O-desmetilcarvedilol [(R)- (+): 6,92 vs 10,40 vs 11,91 ng.h/mL e (S)-(-): 2,36 vs 4,26 vs 3,98 ng/h/mL] são menores no grupo de pacientes portadores de diabetes mellitus tipo 2 quando comparados ao grupo de voluntários sadios não comedicados ou comedicados. Em compensação, os valores de AUC de ambos os enantiômeros do metabólito hidroxifenilcarvedilol [(R)-(+): 13,89 vs 6,60 vs 4,88 ng.h/mL e (S)-(-): 7,21 vs 1,50 vs 1,45 ng/h/mL] são maiores no grupo de pacientes portadores de diabetes mellitus tipo 2. Os parâmetros farmacocinéticos de um paciente metabolizador lento do CYP2D6, portador de diabetes mellitus tipo 2 e em tratamento com glibenclamida e metformina, permite inferir redução na formação de ambos os enantiômeros do metabólito hidroxifenilcarvedilol compensada pelo aumento na formação de ambos os enantiômeros do metabólito O-desmetilcarvedilol. Logo, a disposição cinética de ambos os enantiômeros do carvedilol sob a forma inalterada não difere entre metabolizadores rápidos e lentos do CYP2D6. O modelo não linear de efeitos mistos para a análise da disposição cinética e metabolismo populacional dos enantiômeros do carvedilol foi desenvolvido no NONMEM v.7.2 é preciso e possui capacidade preditiva adequada avaliada por métodos visuais do ajuste do modelo aos dados e ii bootstrap. Os valores de biodisponibilidade estimados pelo modelo para os enantiômeros (S)-(-) e (R)-(+)-carvedilol, respectivamente 16,43 e 25,4%, não diferem entre voluntários sadios e pacientes portadores de diabetes mellitus tipo 2 em tratamento com glibenclamida e metformina. Os valores de clearance pelo CYP2D6 estimados para o (S)-(-)-carvedilol foram de 1,65 vs 7,28 L/h, respectivamente, para os voluntários sadios e para os pacientes diabéticos, enquanto os estimados para o enantiômero (R)-(+)-carvedilol foram de 2,69 vs 13,7 L/h. Em relação ao clearance pelo CYP2C9, os valores estimados para o (S)-(-)-carvedilol foram de 16,2 vs 7,71 L/h, respectivamente, para os voluntários sadios e para os pacientes diabéticos, enquanto os estimados para o enantiômero (R)-(+)-carvedilol foram de 25,6 vs 10,5 L/h. Os valores de clearance por outras vias metabólicas são maiores para o (S)-(-)- carvedilol do que para o (R)-(+)-carvedilol (28,2 vs 4,86 L/h) e não diferem entre voluntários sadios e pacientes. Os valores de clearance total de ambos os enantiômeros do carvedilol não diferem entre os voluntários sadios e os pacientes portadores de diabetes mellitus tipo 2 [(S)-(-): 46,05 vs 43,19 L/h e (R)-(+): 33,15 vs 29,06 L/h], considerando que os menores clearances do CYP2C9 são compensados por maiores clearances do CYP2D6. A variação da frequência cardíaca induzida pelo exercício isométrico com o handgrip após a administração de dose única oral de 25 mg de carvedilol racêmico não mostra relação com as concentrações plasmáticas do (S)-(-)-carvedilol. / Carvedilol is an antihypertensive available as racemic mixture, the (S)-(-)- carvedilol is a ??and ?1 adrenergic blocker and (R)-(+)-carvedilol is only na ?1- adrenergic blocker. Carvedilol is metabolized primarily by glucuronidation and by CYP2D6 to hidroxifenilcarvedilol and CYP2C9 to O-desmetilcarvedilol. This study evaluates the disposition and metabolism of carvedilol, hidroxyphenilcarvedilol and Odesmethylcarvedilol enantiomers in health (n=13) and type II diabetes subjects treated with glibenclamide (5 mg/8h) and in a good glycemic control (n=13) and in a CYP2D6 poor metabolizer diabetes subject (n=1). The subjects received a single racemic carvedilol dose of 25 mg. blood samples wore collected until 24h. The heart rate was evaluated durig isometric handgrip exercise. Carvedilol and metabolites enantiomers wore evaluated in plasma sampels by LC-MS/MS. The pharmacokinetics was evaluate by noncompartimental model and higher levels of (R)-(+)-carvedilol, (R)-(+)-Odesmethylcarvedilol e (R)-(+)-hidroxiphenilcarvedilol levels are noticed. The carvedilol pharmacokinetics does not change between healthy and type II diabetes subjects. However the AUC values of both O-desmethylcarvedilol enantiomers are lower [(R)-(+): 6,92 vs 10,40 vs 11,91 ng.h/mL e (S)-(-): 2,36 vs 4,26 vs 3,98 ng/h/mL]in the diabetes subjects and the AUC values of both hidroxyphenilcarvedilol enantiomers are higher [(R)-(+): 13,89 vs 6,60 vs 4,88 ng.h/mL e (S)-(-): 7,21 vs 1,50 vs 1,45 ng/h/mL]. It is noticed in CYP2D6 poor metabolizer diabetes subject lower levels of hidroxyphenilcarvedilol but higher of O-desmetilcarvedilol and carvedilol disposition is not changed. A Non-linear mixed effects modelling was performed in NONMEM v.7.2 the model was validated by visual methods and bootstrap. The bioavailability of (S)-(-) and (R)-(+)-carvedilol was 16,43 e 25,4% and no covariate effect was noticed. The CYP2D6 clearance values were 1,65 vs 7,28 L/h to healthy and diabetes subjects, inasmuch (R)-(+)-carvedilol ones were 25,6 vs 10,5 L/h. The CYP2C9 clearance of (S)-(-)-carvedilol were 16,2 vs 7,71 L/h for healthy and diabetes subjects, while (R)- (+)-carvedilol ones were 25,6 vs 10,5 L/h. The (S)-(-)-carvedilol clearance by other metabolic routes are higher (28,2 vs 4,86 L/h) and does not change between healthy and diabetes subjects. Carvedilol total clearance also does not differ between healthy and diabetes subjects the because the lower CYP2C9 clearance are balanced by the higher CYP2D6 clearance. The cardiac frequency change induced by handgrip isometric exercise is not related with the (S)-(-)-carvedilol plasma levels.

Les immunosuppresseurs sont des médicaments ayant démontré leur efficacité dans la prévention du rejet de transplantation d’organe solide. Néanmoins, ces médicaments présentent une importante variabilité de la réponse pharmacologique notamment liée à une variation de leur pharmacocinétique. Cette variabilité peut être à l’origine d’un défaut d’efficacité du traitement ou de sur-expositions entrainant une toxicité. Le suivi thérapeutique pharmacologique (STP) des concentrations sanguines d’immunosuppresseur permet de limiter ces risques de sur ou de sous-exposition en facilitant l’adaptation de posologie de ces traitements. En dépit de l'utilisation intensive du STP des concentrations d'immunosuppresseurs chez le transplanté d'organe, la fréquence du rejet aigu a peu diminué au cours de ces dernières années et reste élevée. Le rejet aigu cellulaire peut, en outre, survenir chez le patient alors même que ses concentrations sanguines sont en zone thérapeutique. C'est pourquoi la recherche d'améliorations de ce suivi thérapeutique ainsi que la recherche de nouveaux moyens de monitoring sont des axes pertinents d'investigation en pharmacologie des immunosuppresseurs. L’objectif de ce travail de doctorat a été de développer de nouveaux outils pharmacologiques de monitoring de l’effet de deux immunosuppresseurs, l’évérolimus et le tacrolimus, dans le but de participer à la maitrise de la variabilité pharmacologique de l’effet immunosuppresseur. Pour la première fois, la pharmacocinétique de l'évérolimus chez le transplanté cardiaque a été modélisée par une approche de population. La modélisation pharmacologique est un des axes actuels d’amélioration du STP des immunosuppresseurs permettant d’évaluer l’impact de covariables démographiques, biologiques et/ou génétiques sur la pharmacocinétique de ces médicaments. L’élaboration de ce modèle doit permettre une individualisation des posologies conduisant à la limitation de la variabilité pharmacocinétique lors d’un traitement par cette molécule.Au cours de ce travail, deux méthodes analytiques ont également été développées par LC-MS/MS pour le dosage intracellulaire de l’évérolimus et du tacrolimus. La mesure des concentrations des immunosuppresseurs à l’intérieur même de la cellule, c’est à dire au niveau de son site d’action, apparait comme une mesure plus pertinente que la simple mesure des concentrations dans le sang. Ces méthodes ont ensuite été évaluées sur des petites cohortes de patients transplantés cardiaques. La faisabilité de tels dosages a été démontrée et a permis la réalisation de la dernière partie présentée au cours de ce travail. En effet, une étude clinique a été réalisée chez le patient transplanté hépatique de novo en vue de rapprocher les concentrations sanguines et intracellulaires de tacrolimus et l'effet sur la protéine cible, la calcineurine. Pour la première fois des pharmacocinétiques intracellulaires complètes ont pu être obtenues permettant la description de la cinétique intracellulaire du tacrolimus. Cette étude a également permis de mettre en évidence et de décrire la relation dose - concentration sanguine - concentration intracellulaire - effet sur la protéine cible du tacrolimus chez le transplanté hépatique. Ces travaux ont permis de jeter les bases nécessaires à la réalisation d'essais cliniques permettant d'évaluer la pertinence d'un suivi longitudinal des concentrations intracellulaires et/ou de l'activité de la calcineurine dans la prévention de rejet de transplantation. Les outils développés au cours de ce travail de doctorat visent, d’une part, à mieux appréhender la variabilité de la réponse pharmacologique au cours d’un traitement immunosuppresseur et, d’autre part, à être des outils de compréhension des mécanismes pharmacocinétiques et cellulaires de ces traitements. L'utilisation de ces outils doit concourir à la diminution de la fréquence du rejet de greffe et à l'amélioration globale de la prise en charge du patient transplanté d'organe. / Immunosuppressive drugs have proven efficacy in the prevention of acute rejection of solid organ transplantation. However, these drugs exhibit substantial variability in pharmacological response due to such a variation in their pharmacokinetics. This variability may be the cause of underexposure with a lack of efficacy or over-exposure causing toxicity. Therapeutic drug monitoring (TDM) of immunosuppressant blood levels can limit the risk of over or underexposure facilitating dosage adjustment of these treatments. Despite the extensive use of TDM, the incidence of acute rejection has declined somewhat in recent years and remains high (in the order of 8-15%). Acute cellular rejection can further occur in patients even though blood levels are within the therapeutic range. That is why improvements in the therapeutic monitoring and new ways of monitoring are relevant lines of investigation in pharmacology.The objective of this phD work was to develop new pharmacological tools for monitoring the effect of two immunosuppressive drugs, everolimus and tacrolimus in order to control the pharmacological variability of the immunosuppressive effect .For the first time, the pharmacokinetics of everolimus in heart transplant was modeled by a population approach. Pharmacological modeling is one of the current areas of improvement of immunosuppressants TDM which allows evaluating the impact of demographic, biological and / or genetic on the pharmacokinetics of these drugs covariates. The development of this model must allow individualization of dosages leading to limit pharmacokinetic variability during treatment with this drug.During this work, two analytical methods were also developed by LC-MS/MS for assaying intracellular tacrolimus and everolimus concentrations. Measuring intracellular concentrations of immunosuppressive drugs, i.e. at its site of action, appears as a more relevant than measuring blood concentrations. These methods were then evaluated on small cohorts of heart transplant patients. The feasibility of such assays has been demonstrated and led to the completion of the last part presented in this work.Indeed, a clinical study was performed in de novo liver transplant patients to evaluate blood and intracellular concentrations of tacrolimus and their effect on the target protein, calcineurin. For the first time complete intracellular pharmacokinetics have been obtained for the description of the profile of the intracellular kinetics of tacrolimus. This study also highlights and describes the relationship dose - blood concentration - intracellular concentration - effect on the target protein of tacrolimus in liver transplant patients. This work might help conducting clinical trials to assess the relevance of a longitudinal follow-up of intracellular concentrations and / or activity of calcineurin in the prevention of transplant rejection.The tools developed in this PhD work aimed, firstly, to better understand the variability of the pharmacological response in immunosuppressive therapy and, secondly, to be tools for understanding the drug mechanisms inside of the cell. The use of these tools should contribute to the decrease in the frequency of graft rejection and the overall improvement in the management of organ transplant patients.

Objectifs : Définir les paramètres pharmacocinétiques du pantoprazole intraveineux en soins intensifs pédiatriques et déterminer l’influence qu’exercent sur ceux-ci les facteurs démographiques, le syndrome de réponse inflammatoire systémique (SRIS), la dysfonction hépatique et l’administration d’un inhibiteur du cytochrome (CYP) 2C19. Méthode : Cent cinquante-six concentrations plasmatiques de pantoprazole provenant d’une population de 20 patients (âgés de 10 jours à 16.4 ans) à risque ou atteints d’une hémorragie gastroduodénale de stress, ayant reçu des doses quotidiennes de pantoprazole de 19.9 à 140.6 mg/1.73m2, ont été analysées selon les méthodes non compartimentale et de modélisation non linéaire à effets mixtes. Résultats : Une clairance médiane (CL) de 0.14 L/h/kg, un volume apparent de distribution de 0.20 L/kg et une demi-vie d’élimination de 1.7 h ont été déterminés via l’approche non compartimentale. Le modèle populationnel à deux compartiments avec une infusion d’ordre zéro et une élimination d’ordre un représentait fidèlement la cinétique du pantoprazole. Le poids, le SRIS, la dysfonction hépatique et l’administration d’un inhibiteur du CYP2C19 constituaient les covariables significatives rendant compte de 75 % de la variabilité interindividuelle observée pour la CL. Seul le poids influençait significativement le volume central de distribution (Vc). Selon les estimations du modèle final, un enfant de cinq ans pesant 20 kg avait une CL de 5.28 L/h et un Vc de 2.22 L. La CL du pantoprazole augmentait selon l’âge et le poids tandis qu’elle diminuait respectivement de 62.3%, 65.8% et 50.5% en présence d’un SRIS, d’un inhibiteur du CYP2C19 ou d’une dysfonction hépatique. Conclusion : Ces résultats permettront de guider les cliniciens dans le choix d’une dose de charge et dans l’ajustement des posologies du pantoprazole en soins intensifs pédiatriques dépendamment de facteurs fréquemment rencontrés dans cette population. / Aims : To characterize the pharmacokinetics of intravenous pantoprazole in a paediatric intensive care population and to determine the influence of demographic factors, systemic inflammatory response syndrome (SIRS), hepatic dysfunction and concomitantly used cytochrome (CYP) 2C19 inhibitors on the drug’s pharmacokinetics. Methods : A total of 156 pantoprazole concentrations from 20 patients (aged from 10 days to 16.4 years) at risk for or with upper gastrointestinal bleeding, who received pantoprazole doses ranging from 19.9 to 140.6 mg/1.73m2/day, were analyzed using non compartmental and non linear mixed effects modelling (NONMEM) approaches. Results : The non compartmental results showed that median clearance (CL), apparent volume of distribution and elimination half-life were 0.14 L/h/kg, 0.20 L/kg and 1.7 h, respectively. The best structural model for pantoprazole was a two-compartment model with zero order infusion and first order elimination. Body weight, SIRS, age, hepatic dysfunction and presence of CYP2C19 inhibitors were the significant covariates affecting CL, accounting for 75% of interindividual variability. Only body weight significantly influenced central volume of distribution (Vc). In the final population model, the estimated CL and Vc were 5.28 L/h and 2.22 L, respectively, for a typical five year old child weighing 20 kg. Pantoprazole CL increased with weight and age whereas the presence of SIRS, CYP2C19 inhibitors and hepatic dysfunction, when present separately, significantly decreased pantoprazole CL by 62.3%, 65.8% and 50.5%, respectively. Conclusion : These results provide important information to physicians regarding selection of a starting dose and dosing regimen of pantoprazole for paediatric intensive care patients based on various factors frequently encountered in this population.

No description available.

O carvedilol é um anti-hipertensivo disponível na clínica como mistura racêmica, sendo o (S)-(-)-carvedilol um bloqueador ? e ?1-adrenérgico e o (R)-(+)-carvedilol apenas ?1-adrenérgico. O carvedilol é metabolizado principalmente por glicuronidação e pelo CYP2D6 a hidroxifenilcarvedilol e pelo CYP2C9 a Odesmetilcarvedilol. O presente estudo avalia a disposição cinética e o metabolismo dos enantiômeros do carvedilol, hidroxifenilcarvedilol e O-desmetilcarvedilol em voluntários sadios não comedicados (n=13) ou comedicados com dose única oral de glibenclamida (5 mg) e metformina (500 mg) (n=13) e em pacientes portadores de diabetes mellitus tipo 2 (com bom controle glicêmico e em tratamento com glibenclamida 5 mg/8h e metformina 500 mg/8h; n=14), fenotipados como metabolizadores rápidos (n=26) ou lentos (n=1). Os voluntários e pacientes receberam dose única oral de 25 mg de carvedilol racêmico e amostras seriadas de sangue foram coletadas até 24h após a administração. A frequência cardíaca foi avaliada na situação de exercício isométrico com o handgrip durante 2 min a 30% da contratilidade voluntária máxima e durante o repouso. Os enantiômeros do carvedilol e metabólitos foram analisados em plasma por LC-MS/MS empregando coluna Chirobiotic® V. O método foi linear no intervalo de 0,05 a 100; 0,05 a 10 e 0,02 a 10 ng/mL para os enantiômeros do carvedilol, hidroxifenilcarvedilol e O-desmetilcarvedilol, os desvios do estudo de precisão e exatidão foram inferiores a 15% e não foi observado efeito matriz. A farmacocinética avaliada por modelo não compartimental mostra acúmulo plasmático dos enantiômeros (R)-(+)-carvedilol, (R)-(+)-O-desmetilcarvedilol e (R)-(+)- hidroxifenilcarvedilol. A disposição cinética e o metabolismo dos enantiômeros do carvedilol não diferem entre os grupos de voluntários não comedicados e comedicados com dose única oral de glibenclamida e metformina. No entanto, os valores de AUC de ambos os enantiômeros do metabólito O-desmetilcarvedilol [(R)- (+): 6,92 vs 10,40 vs 11,91 ng.h/mL e (S)-(-): 2,36 vs 4,26 vs 3,98 ng/h/mL] são menores no grupo de pacientes portadores de diabetes mellitus tipo 2 quando comparados ao grupo de voluntários sadios não comedicados ou comedicados. Em compensação, os valores de AUC de ambos os enantiômeros do metabólito hidroxifenilcarvedilol [(R)-(+): 13,89 vs 6,60 vs 4,88 ng.h/mL e (S)-(-): 7,21 vs 1,50 vs 1,45 ng/h/mL] são maiores no grupo de pacientes portadores de diabetes mellitus tipo 2. Os parâmetros farmacocinéticos de um paciente metabolizador lento do CYP2D6, portador de diabetes mellitus tipo 2 e em tratamento com glibenclamida e metformina, permite inferir redução na formação de ambos os enantiômeros do metabólito hidroxifenilcarvedilol compensada pelo aumento na formação de ambos os enantiômeros do metabólito O-desmetilcarvedilol. Logo, a disposição cinética de ambos os enantiômeros do carvedilol sob a forma inalterada não difere entre metabolizadores rápidos e lentos do CYP2D6. O modelo não linear de efeitos mistos para a análise da disposição cinética e metabolismo populacional dos enantiômeros do carvedilol foi desenvolvido no NONMEM v.7.2 é preciso e possui capacidade preditiva adequada avaliada por métodos visuais do ajuste do modelo aos dados e ii bootstrap. Os valores de biodisponibilidade estimados pelo modelo para os enantiômeros (S)-(-) e (R)-(+)-carvedilol, respectivamente 16,43 e 25,4%, não diferem entre voluntários sadios e pacientes portadores de diabetes mellitus tipo 2 em tratamento com glibenclamida e metformina. Os valores de clearance pelo CYP2D6 estimados para o (S)-(-)-carvedilol foram de 1,65 vs 7,28 L/h, respectivamente, para os voluntários sadios e para os pacientes diabéticos, enquanto os estimados para o enantiômero (R)-(+)-carvedilol foram de 2,69 vs 13,7 L/h. Em relação ao clearance pelo CYP2C9, os valores estimados para o (S)-(-)-carvedilol foram de 16,2 vs 7,71 L/h, respectivamente, para os voluntários sadios e para os pacientes diabéticos, enquanto os estimados para o enantiômero (R)-(+)-carvedilol foram de 25,6 vs 10,5 L/h. Os valores de clearance por outras vias metabólicas são maiores para o (S)-(-)- carvedilol do que para o (R)-(+)-carvedilol (28,2 vs 4,86 L/h) e não diferem entre voluntários sadios e pacientes. Os valores de clearance total de ambos os enantiômeros do carvedilol não diferem entre os voluntários sadios e os pacientes portadores de diabetes mellitus tipo 2 [(S)-(-): 46,05 vs 43,19 L/h e (R)-(+): 33,15 vs 29,06 L/h], considerando que os menores clearances do CYP2C9 são compensados por maiores clearances do CYP2D6. A variação da frequência cardíaca induzida pelo exercício isométrico com o handgrip após a administração de dose única oral de 25 mg de carvedilol racêmico não mostra relação com as concentrações plasmáticas do (S)-(-)-carvedilol. / Carvedilol is an antihypertensive available as racemic mixture, the (S)-(-)- carvedilol is a ??and ?1 adrenergic blocker and (R)-(+)-carvedilol is only na ?1- adrenergic blocker. Carvedilol is metabolized primarily by glucuronidation and by CYP2D6 to hidroxifenilcarvedilol and CYP2C9 to O-desmetilcarvedilol. This study evaluates the disposition and metabolism of carvedilol, hidroxyphenilcarvedilol and Odesmethylcarvedilol enantiomers in health (n=13) and type II diabetes subjects treated with glibenclamide (5 mg/8h) and in a good glycemic control (n=13) and in a CYP2D6 poor metabolizer diabetes subject (n=1). The subjects received a single racemic carvedilol dose of 25 mg. blood samples wore collected until 24h. The heart rate was evaluated durig isometric handgrip exercise. Carvedilol and metabolites enantiomers wore evaluated in plasma sampels by LC-MS/MS. The pharmacokinetics was evaluate by noncompartimental model and higher levels of (R)-(+)-carvedilol, (R)-(+)-Odesmethylcarvedilol e (R)-(+)-hidroxiphenilcarvedilol levels are noticed. The carvedilol pharmacokinetics does not change between healthy and type II diabetes subjects. However the AUC values of both O-desmethylcarvedilol enantiomers are lower [(R)-(+): 6,92 vs 10,40 vs 11,91 ng.h/mL e (S)-(-): 2,36 vs 4,26 vs 3,98 ng/h/mL]in the diabetes subjects and the AUC values of both hidroxyphenilcarvedilol enantiomers are higher [(R)-(+): 13,89 vs 6,60 vs 4,88 ng.h/mL e (S)-(-): 7,21 vs 1,50 vs 1,45 ng/h/mL]. It is noticed in CYP2D6 poor metabolizer diabetes subject lower levels of hidroxyphenilcarvedilol but higher of O-desmetilcarvedilol and carvedilol disposition is not changed. A Non-linear mixed effects modelling was performed in NONMEM v.7.2 the model was validated by visual methods and bootstrap. The bioavailability of (S)-(-) and (R)-(+)-carvedilol was 16,43 e 25,4% and no covariate effect was noticed. The CYP2D6 clearance values were 1,65 vs 7,28 L/h to healthy and diabetes subjects, inasmuch (R)-(+)-carvedilol ones were 25,6 vs 10,5 L/h. The CYP2C9 clearance of (S)-(-)-carvedilol were 16,2 vs 7,71 L/h for healthy and diabetes subjects, while (R)- (+)-carvedilol ones were 25,6 vs 10,5 L/h. The (S)-(-)-carvedilol clearance by other metabolic routes are higher (28,2 vs 4,86 L/h) and does not change between healthy and diabetes subjects. Carvedilol total clearance also does not differ between healthy and diabetes subjects the because the lower CYP2C9 clearance are balanced by the higher CYP2D6 clearance. The cardiac frequency change induced by handgrip isometric exercise is not related with the (S)-(-)-carvedilol plasma levels.

Tuberculosis, the leading cause of death by a single infection disease caused by bacteria, requires long treatments and the bacteria are prone to develop drug resistance. Therefore, new efficient treatment regiments needs developing, which requires new tools for drug development. A major reason for discontinuance of a drug under development is undesired pharmacokinetic properties. Therefore, it is important to have early information of this, preferably the first time the drug is tested in animals. The first in vivo pharmacokinetic experiment is often done in mice and the only information present at this stage are often in vitro values and physicochemical properties. Physiological-based pharmacokinetic modelling can be used to extrapolate from in vitro to in vivo values. From this, the first in vivo pharmacokinetic experiment can be designed, often with the goal of reducing the amount of mice. This goal is one of the three R.s and it is called Reduction. To explore the Reduction of an experiment population pharmacokinetic modelling can be utilized via exploration of the imprecision, bias and probability of an informative experiment to evaluate if a design meets the goal of Reduction. In this report a recommendation of the first in vivo pharmacokinetic experiment is presented. This is based on in vitro values and physicochemical properties that are common in anti-tuberculosis drugs. If the probability of an informative experiment is critical, a terminal sampling of 40 mice is recommended. If imprecision and bias are necessary, zipper sampling of 10 mice is recommended.

La vancomycine est l'un des antibiotiques les plus prescrits, principalement utilisé pour les infections suspectées et confirmées à Staphylococcus aureus résistant à la méthicilline (SARM). Les infections par des souches de SARM font peser une charge importante sur le système de santé, à laquelle s'ajoute l'incertitude qui demeure quant à la posologie optimale de la vancomycine. Les récentes lignes directrices révisées sur le suivi thérapeutique de la vancomycine, publiées en 2020, avalisent principalement l'estimation directe de l'aire sous la courbe de concentration en fonction du temps (AUC) par l'utilisation d'équations bayésiennes ou pharmacocinétiques (PK) de premier ordre pour le suivi thérapeutique. Pour mieux informer la posologie de la vancomycine, nous avons d'abord mis à jour une revue précédente des analyses pharmacocinétiques de population (PopPK) de la vancomycine publiées chez les adultes et les enfants. Pour ce faire, nous avons déterminé les caractéristiques des modèles pharmacocinétiques rapportés et identifié les diverses sources potentielles de variabilité observées dans différentes sous-populations particulières. Motivés par la controverse existante autour des nouvelles directives de surveillance thérapeutique de la vancomycine et par l'absence d'une étude approfondie des méthodes recommandées, nous avons recueilli des données hospitalières et construit un cadre de modélisation qui nous a permis d'évaluer les recommandations des directives sur les méthodes de surveillance, tout en considérant une variété de scénarios et d'hypothèses cliniques réalistes. Notre analyse a confirmé que la surveillance bayésienne est la méthode la plus rapide et la plus fiable, à condition qu'elle soit correctement mise en œuvre, la plus importante condition pour cela étant l'utilisation de modèles bayésiens a priori appropriés. De plus, nous avons montré que le suivi bayésien ne nécessite pas nécessairement des niveaux de concentration de types creux ou pic et peut en fait être réalisé en utilisant un niveau aléatoire. Aussi, nous avons démontré que l'utilisation correcte des équations pharmacocinétiques de premier ordre exigerait au moins deux mesures de concentration à l'état d'équilibre. L’utilisation de la méthode creux-seulement de la vancomycine à l'état d'équilibre peut être tout aussi efficace dans certaines situations que nous avons explorées ici. En considérant la larges étendue et la grande variabilité des populations traitées à la vancomycine en termes d'âge, de gravité de l'infection et de scénarios cliniques, cette thèse adopte un regard objectif pour évaluer quantitativement le gain potentiel de chaque méthode de surveillance de la vancomycine, en explorant leur adéquation en termes d'effort nécessaire, de disponibilité des ressources et de gain potentiel. Compte tenu des lignes directrices sur la vancomycine récemment publiées et de la controverse qui persiste, nous pensons que cette thèse a permis de démêler la variété et la complexité de l'utilisation de la vancomycine et a apporté un éclairage supplémentaire plus objectifvement informé vers un suivi thérapeutique optimal de la vancomycine. / Vancomycin is among the most prescribed antibiotics, mainly used for suspected and confirmed methicillin-resistant Staphylococcus aureus (MRSA) infections. Infections by MRSA strains carry a substantial burden on the health care system, supplemented by the uncertainty that remains regarding vancomycin optimal dosing. The recent revised vancomycin therapeutic monitoring guidelines published in 2020, endorsed primarily the direct estimation of area under the concentration-time curve (AUC) through the use of Bayesian or first-order pharmacokinetic (PK) equations monitoring. To better inform vancomycin dosing, we first updated a previous review of published vancomycin population pharmacokinetic (PopPK) analysis in both adults and children. This was accomplished by determining the characteristics of the reported pharmacokinetic models and identifying the potential various sources of variability observed in different special subpopulations. Motivated by the existing controversy around the new vancomycin therapeutic monitoring guidelines and the lack of a thorough investigation of the recommended methods, we collected hospital data and built a modeling framework that allowed us to assess the guideline recommendations of monitoring methods while considering a variety of realistic clinical scenarios and assumptions. Our analysis affirmed that Bayesian monitoring is the fastest and most reliable method, conditional on its proper implementation, the most important being the use of proper Bayesian priors. Moreover, we showed that Bayesian monitoring does not necessarily require trough or peak concentration levels and can in fact be performed using a random level. Proper use of first-order PK equations required at least two steady-state concentration measurements. Alternatively, simpler trough-only vancomycin monitoring near steady-state can be as effective in certain cases that we explored here. By considering the wide ranges and the high variability in populations treated with vancomycin in terms of age, the severity of infection, and clinical scenarios, this thesis takes an objective look to quantitatively assess the potential gain of each vancomycin drug monitoring method, by investigating their suitability in terms of the effort needed, the availability of resources and the resulting gain. Considering the recently released vancomycin guidelines and the ensuing controversies between well-established clinical teams, we believe that this dissertation helped untangle the variety and complexity of vancomycin use and brought additional insights towards a more objective and optimal vancomycin therapeutic monitoring.

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