Chemotherapeutic Agents

• Chemotherapy 


  -Use of drugs that destroys specific agents of disease (bacteria, fungi, virus, parasites)

  -use of drug in treatment of neoplastic disease
• Chemotherapeutic Agents


  -drugs used in chemotherapy

  • antibiotics
  • antifungal
  • antiprotozoal
  • antiviral
  • antineoplastic
• Paul Ehrlich


  -father of chemotherapy

  -created arsphenamine (Salvarsan) *cure syphilis

  -popularized the magic bullet concept
• Antibiotics 


  -chemical subusence

  • Penicillin
  • streptomycin
• Antimicrobial Agent


  -natural, (semi) synthetic

  • sulfonamide
• selectivpity (selective toxicpity)


  -kill invading microbes w/o harming the host cell
• potency


  -antimicrobial agents per mg
• Chemotherapeutic Index


  -ratio of maximum tolerated dose
• therapeutic index 


  -ratio of dose toxic to the host
• Minimum inhibitory concentration 


  -lowest concentration of antimicrobial agent
• MIC90


  -mic inhibit 90% of microorganisms tested
• minimum bacterial concentration (mbc)

  -lowest concentration

  -kills 99.9% of og bacteria
• minimum antibiotic concentration (mac)

  -reduces growth of microbes x10

  $MAC=$$1 of MIC/ 10TH$
• CATEGORIES OF ANTIBIOTICS


  • bactericidal
  • bacteriostatic
• Bactericidal


  -drugs kill target bacteria

  -defense mechanism is weakened

  -used for weak animals

  • aminoglycosides
  • fluoroquinolones
  • beta lactams
• Bacteriostatic


  -drugs inhibit growth of bacteria

  -duration therapy must be sufficient

  • sulphionamides
  • chloramphenicol
• Post antibiotic effect


  -growth inhibition that continues for a varying period of time
• Selection of Antimicrobial Agents

  1. organism related factor
  2. drug related factor
  3. host factor
• Organism related factor 


  • Target organism
• drug related factor


  • type of activity
  • pharmacokinetic profile
  • drug interaction
  • route of administration
  • relative toxicity
  • cost of therapy
  • spectrum of activity
• Host factors 


  • host defense mechanism
  • pathological condition
  • pregnancy
  • genetic factors
  • age
  • local factors
  • phs
• Effect of combination therapy 


  1. synergism
  2. additivity
  3. antagonism
• Synergism


  -interaction bet two or more drugs

  • aspirin
  • caffeine
• Additivity


  -Effect if two drugs in combination

  • aspirin
  • acetaminophen
• Antagonism


  -two or more chemicals combine to produce

  • insulin
  • glucagon