The gives information about for Chemotherapy, their classification,therapeutic and drug interactions.

1. CHEMOTHERAPYCHEMOTHERAPY
By- Punyatoya
Mohanty
Biology Faculty

2. CHEMOTHERAPYCHEMOTHERAPY
 ANTIBIOTICSANTIBIOTICS
Chemical substances produced byChemical substances produced by
microorganisms and havemicroorganisms and have the capacitythe capacity toto
inhibit or destroy other organisms .inhibit or destroy other organisms .
 CHEMOTHERAPEUTIC AGENTCHEMOTHERAPEUTIC AGENT
 Synthetic chemical substances used toSynthetic chemical substances used to
inhibit or destroy microorganismsinhibit or destroy microorganisms..

3. CLASSIFICATION OF ANTIBIOTICSCLASSIFICATION OF ANTIBIOTICS
ACCORDING TO MECHANISM OF ACTIONACCORDING TO MECHANISM OF ACTION
 !INHIBITION OF CELL WALL!INHIBITION OF CELL WALL
SYNTHESIS.SYNTHESIS.
 INHIBITION OFINHIBITION OF PROTEINPROTEIN
SYNTHESISSYNTHESIS ..
 INHIBITION OF NUCLEIC ACIDINHIBITION OF NUCLEIC ACID
SYNTHESISSYNTHESIS ..
 INHIBITION OF CELL MEMBRANEINHIBITION OF CELL MEMBRANE
FUNCTIONS .FUNCTIONS .

4. According to spectrumAccording to spectrum
 1- Narrow spectrum as penicillins1- Narrow spectrum as penicillins
,aminoglycosides,aminoglycosides
 2- Broad spectrum as tetracyclines ,2- Broad spectrum as tetracyclines ,
chloramphenicolchloramphenicol

5. REASONS FOR FAILUREREASONS FOR FAILURE OFOF
CHEMOTHERAPYCHEMOTHERAPY ..
 1-WRONG DIAGNOSIS1-WRONG DIAGNOSIS
2-WRONG CHOICE Of DRUG2-WRONG CHOICE Of DRUG
3-WRONG DOSE3-WRONG DOSE
4-DEVELOPMENT OF RESISTANCE4-DEVELOPMENT OF RESISTANCE
5-INFECTIONS WITH5-INFECTIONS WITH MORE THANMORE THAN
ONE ORGANISMONE ORGANISM
6-PRESENCE OF PUS ,BLOOD6-PRESENCE OF PUS ,BLOOD
,,NECROTIC TISSUESNECROTIC TISSUES ..

6. Host factors in selection ofHost factors in selection of
antimicrobial therapyantimicrobial therapy
 1-Allergy or history of adverse reactions.1-Allergy or history of adverse reactions.
 2-Age of patient2-Age of patient
 3-Pregnancy3-Pregnancy
 4-Genetic or metabolic abnormalities4-Genetic or metabolic abnormalities
5-Renal & hepatic functions5-Renal & hepatic functions
6-Site of infections6-Site of infections
7-Concomitant drug therapy7-Concomitant drug therapy
 8-Underlying disease state(s)8-Underlying disease state(s)

7. Failure of AntimicrobialFailure of Antimicrobial
therapytherapy
 1-Failure caused by drug selection:1-Failure caused by drug selection:
 Inappropriate drug selection or dosage or route ofInappropriate drug selection or dosage or route of
administration . For example:administration . For example:
 Selection of a bacteriostatic drug for endocarditis.Selection of a bacteriostatic drug for endocarditis.
 administration of a drug by I.M. to a patient with a weakadministration of a drug by I.M. to a patient with a weak
peripheral circulationperipheral circulation
( shock). May result inadequate therapy.( shock). May result inadequate therapy.
 Malabsorption of a drug product because of GIT disease or a drugMalabsorption of a drug product because of GIT disease or a drug
interaction ( combination of tetracyclines with milk products ).interaction ( combination of tetracyclines with milk products ).
 Accelerated drug elimination as in patient with cystic fibrosis orAccelerated drug elimination as in patient with cystic fibrosis or
during pregnancy may result in rapid clearance or large volumeduring pregnancy may result in rapid clearance or large volume
of distribution resulting in low serum concentrations as withof distribution resulting in low serum concentrations as with
aminoglycosides.aminoglycosides.
 Inactivation of antimicrobial agents by another drug.Inactivation of antimicrobial agents by another drug.
 Poor penetration into the site of infection ( c.n.s., eye, prostate).Poor penetration into the site of infection ( c.n.s., eye, prostate).

8. Failure caused byFailure caused by
microorganisms(BACTERIALmicroorganisms(BACTERIAL
RESISTANCE )RESISTANCE )
 1-Inactivation of antibiotics by enzymes1-Inactivation of antibiotics by enzymes..
 2-2- Modification of target by mutationModification of target by mutation..
3-Impaired penetration of drug to target3-Impaired penetration of drug to target
,,occurs only in gram-negative species.occurs only in gram-negative species.
4-The presence of an efflux pump4-The presence of an efflux pump produced byproduced by
gram-negative organisms which consists ofgram-negative organisms which consists of
cytoplasmic and periplasmic proteincytoplasmic and periplasmic protein
components that transport antibiotics from thecomponents that transport antibiotics from the
periplasm back across the outer membrane.periplasm back across the outer membrane.

9. ANTIMICROBIALANTIMICROBIAL
COMBINATIONCOMBINATION
 SYNERGISMSYNERGISM
!-SEQUENTIAL SYNERGISM!-SEQUENTIAL SYNERGISM
2-INHIBITION2-INHIBITION OF ENZYMATICOF ENZYMATIC
ACTIVITYACTIVITY
 3-ENHANCEMENT OF3-ENHANCEMENT OF
ANTIMICROBIALANTIMICROBIAL UP TAKEUP TAKE
 ANTAGONISMANTAGONISM

10. Aim of chemotherapeuticAim of chemotherapeutic
combinationcombination
 1-1-Broaden the spectrum of antibacterial activity e.g:Broaden the spectrum of antibacterial activity e.g:
clindamycin+ gentamycinclindamycin+ gentamycin
 2- Reduce the doses2- Reduce the doses
 3- Reduce the side effects3- Reduce the side effects
 4- Overcome drug resistance(delay the rate of drug4- Overcome drug resistance(delay the rate of drug
resistance) as in treatment of TB or pseudomonalresistance) as in treatment of TB or pseudomonal
infections.infections.
 5- Produce a more potent compound5- Produce a more potent compound
 (produce a synergistic effect) as in co-trimoxazole(produce a synergistic effect) as in co-trimoxazole
combination or as in penicillin with gentamycin incombination or as in penicillin with gentamycin in
treatment of bacterial endocarditis.treatment of bacterial endocarditis.
 6-Treatment of severe infections of unknownetiology as in6-Treatment of severe infections of unknownetiology as in
septicaemia.septicaemia.

11. Drug interactions with antibioticsDrug interactions with antibiotics
 1- Aminoglycosides1- Aminoglycosides
 A- Increase the effects of curareA- Increase the effects of curare
 B- Increase the nephrotoxicity & ototoxicity ofB- Increase the nephrotoxicity & ototoxicity of
loop diureticsloop diuretics
 2- Enzyme inhibitors as chloramphenicol &2- Enzyme inhibitors as chloramphenicol &
erythromycin increase the action & toxicity oferythromycin increase the action & toxicity of
other drugs as digitalisother drugs as digitalis
 3- Enzyme inducers as rifampicin decrease the3- Enzyme inducers as rifampicin decrease the
action of other drugs as oral anticoagulants or oralaction of other drugs as oral anticoagulants or oral
contraceptives.contraceptives.

12. Drug interactionsDrug interactions
 4- Sulphamethoxazole + trimethoprim result4- Sulphamethoxazole + trimethoprim result
in bactericidal effect.in bactericidal effect.
 Sulphonamides displace oral hypoglycemicSulphonamides displace oral hypoglycemic
from their plasma protein binding causingfrom their plasma protein binding causing
hypoglycemiahypoglycemia