CLINICAL-USE-OF-ANTIBIOTICS课件.ppt

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1、CLINICAL USE OF ANTIBIOTICSBroad-spectrum:Justifiable in life-threatening disease,with unidentified organismIn general more expensive more likely to resistanceMore adverse effects than narrow spectrum(inc.superinfection)Narrow spectrum:Preferable if possibleDangerous choice in life-threatening disea

2、se unless organism(and sensitivities)knownPrinciples for prescribing antibioticsMake a diagnosis of bacterial infection and consider likely organisms/sensitivitiesTake appropriate specimens for culture/sensitivityAre AB needed at all?Need for urgent therapy before culture data available?Seriously il

3、l patients empirical ABThis may prevent confirmation of diagnosis or the ID of the organismMajor antibioticsPenicillinsCephalosporinsAminoglycosidesMacrolidesQuinolonesAntifolatesMetronidazoleMode of action in briefSpectrum in briefClinical pharmacokinetics:just the important bitsIndications and mod

4、es of useContraindicationsAdverse effectsDrug interactionsMonitor:clinically,microbiologically,PKCombinations are occasionally used:Mixed infections,e.g.in peritonitisTo achieve synergismOrganism unknown and serious illnessTo prevent the development of resistanceMode of actionacts on the cell wallSp

5、ectrum in briefmainly Gram+Benzyl penicillin:narrow spectrum,Pneumococcus,MeningococcusAmoxycillin:broader spectrum,including HaemophilusFlucloxacillin:Staphylococcus aureusClinical pharmacokineticsBenzyl pen:acid labileOthers:many routesCross BBB poorly except when inflamedRenal eliminationIndicati

6、ons and modes of useNo need for TDMContraindicationsHypersensitivityGIT upset(renal impairment)Adverse effectsGastrointestinal upsets(common)Drug interactionsOnly good onesPenicillinsMode of actionProtein synthesisSpectrum in briefGram+Atypical organisms(Chlamydia,Legionella)Clinical pharmacokinetic

7、sErythromycinAcid labile(overcome by formulation)absorption can be erraticPoor BBBMetabolised in liverIndications and modes of usePenicillin allergyOral and IVContraindicationsHypersensAdverse effectsGastrointestinal upsets(common)Rarely hypersensitivity,or cholestatic jaundiceInteractionsEnzyme inh

8、ibitor MacrolidesMode of actionDHFRDHPSSpectrum in briefGram+and Pneumocystitis cariniiClinical pharmacokineticsBoth trimethoprim and sulphonamides eliminated renallyIndications and modes of useUTIURTIPCPContraindicationsSulphonamide allergyAdverse effectsAllergyMegaloblastic anaemiaDrug interaction

9、sCotrimoxazole:enzyme inhibitionAntifolates Mode of actionDNA gyraseSpectrum in briefMainly Gram Clinical pharmacokineticsWell absorbedCiprofloxacinRenal and hepatic eliminationIndications and modes of useUTILife threatening bacteraemias(IV)ContraindicationsBone damage in childrenEpilepsyAdverse effectsGastrointestinal upsetsGABA:confusion in the elderly and lower the fitting thresholdDrug interactionsEnzyme inhibitorQuinolones