Pharmacokinetics.ppt

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1、PharmacokineticsChapter4Copyright(c)2004ElsevierInc.Allrightsreserved.PharmacokineticsFourbasicpharmacokineticprocessesareAbsorptionDistributionMetabolismExcretionCopyright(c)2004ElsevierInc.Allrightsreserved.FactorsAffectingDrugAbsorptionRateofdissolutionSurfaceareaBloodflowLipidsolubilitypHpar

2、titioningCopyright(c)2004ElsevierInc.Allrightsreserved.RoutesofAdministrationTwomajorgroupsEnteralViagastrointestinaltractParenteralOutsidethegastrointestinaltractUsuallyreferredtoas“byinjection”Commonroutes—intravenous,subcutaneous,intramuscularCopyright(c)2004ElsevierInc.Allrightsreserved.Drug

3、DistributionFactorsinfluencingdistributionareBloodflowtotissue–Exitingthevascularsystem–Theblood-brainbarrier–PlacentaldrugtransferCopyright(c)2004ElsevierInc.Allrightsreserved.DrugMetabolismBiotransformationEnzymaticalterationofdrugstructureLiver—primarysiteofdrugmetabolismP450system(cytochrome

4、P450)Copyright(c)2004ElsevierInc.Allrightsreserved.DrugMetabolism—ImplicationsTherapeuticconsequencesareAccelerateddrugexcretionDruginactivationIncreasedtherapeuticactionActivationofprodrugsToxicityvariationsCopyright(c)2004ElsevierInc.Allrightsreserved.SpecialConsiderationsinDrugMetabolismAgeIn

5、ductionofdrug-metabolizingenzymesFirst-passeffectNutritionalstatusCompetitionbetweendrugsCopyright(c)2004ElsevierInc.Allrightsreserved.DrugExcretionRemovalofdrugfromthebodyKidney—viathreeprocessesGlomerularfiltrationPassivetubularreabsorptionActivetubularsecretionCopyright(c)2004ElsevierInc.Allr

6、ightsreserved.TimeCourseofDrugResponsesPlasmadruglevelsMinimumeffectiveconcentration(MEC)ToxicconcentrationTherapeuticrangeDrughalf-lifeLoadingdoseMaintenancedoseCopyright(c)2004ElsevierInc.Allrightsreserved.DrugHalf-lifeThetimefortheamountofdruginthebodytodecreaseby50%Copyright(c)2004ElsevierIn

7、c.Allrightsreserved.