Antimicrobial use in lung infection and antiviral drugs

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Anonymous
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297007
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Antimicrobial use in lung infection and antiviral drugs
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2015-02-27 07:23:03
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Antimicrobial Antiviral Pharmacology
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Vet Med - Module 9
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  1. List the three major classes of antimicrobials used for treating lung infections
    Tetracyclines, macrolides, fluoroquinolones
  2. How do tetracylines get into bacteria and have their action?
    They diffuse across the outer cell membrane and use an active carrier mediated process to cross the inner cell membrane.  They bind reversibly to the bacterial ribosome to inhibit bacterial protein synthesis.
  3. Are tetracyclines bacteriostatic or bactericidal?
    Bacteriostatic
  4. Describe where the tetracyclines bind on the bacterial ribosome
    They bind on the 30s subunit and block it.  The tRNA cannot dock so the amino acid cannot be added to the protein chain and this stops protein synthesis.
  5. How are the tetracyclines usually administered? Why?
    They are usually administered IV or IM as their oral absorption is low
  6. What would further decrease oral absorption of tetracyclines?
    Food, and metal ions e.g. calcium and magnesium as they chelate these
  7. Do tetracyclines get into the brain?
    Generally not
  8. True or false: tetracyclines can cross the placenta and be secreted in milk?
    True
  9. Why are tetracyclines also good for treating urinary infections?
    As they undergo minimal metabolism and are excreted unchanged in the urine and (to a lesser extent) bile
  10. What is the half life of the tetracyclines?
    6-10hrs
  11. Why will impaired renal function increase the half life?
    As glomerular filtration is a mechanism of urinary excretion
  12. Why may horses have problems with tetracyclines?
    As they are excreted into the bile and so will constantly drip into the GI tract affecting normal microflora
  13. Give two examples of semi synthetic derivatives of tetracycline
    Minocycline and doxycycline
  14. Are minocycline and doxycycline more/less lipid soluble than tetracycline?
    More lipid soluble
  15. Do minocycline and doxycycline have good or bad oral absorption?
    Good
  16. What are tetracyclines particularly useful for?
    Mixed bacterial infections
  17. Give an example of a macrolide
    Erythromycin, tilmicosin, tylosin, spiramycin, tulathromycin
  18. Are macrocodes bactericidal or bacteriostatic?
    Bacteriostatic
  19. What is the mechanism of action of the macrolides?
    The macrolides act on the 50s subunit.  They do not allow movement of tRNA from the A to P site.  The P site is blocked which inhibits protein synthesis.
  20. Do the macrolides have a high or low intracellular concentration?
    High
  21. Can macrolides cross the bbb?
    No
  22. What type of cell can macrolides enter and accumulate in?
    Phagocytes
  23. Do macrocodes increase/decrease mucus production?
    Decrease
  24. True or false: macrolides have anti-inflammatory actions?
    True - they inhibit pro-inflammatory cytokines
  25. Is erythromycin a weak acid or weak base?
    Weak base
  26. What type of fluids will erythromycin become trapped in?
    Weak acid e.g. milk, urine
  27. Does erythromycin have a high/low lipid solubility?
    High
  28. Is erythromycin well absorbed orally?  What lowers oral absorption?
    Yes, food lowers oral absorption
  29. How is erythromycin excreted?
    It is partially inactivated by hepatic metabolism and is excreted in bile (so lost in faeces).  Urinary excretion is low.
  30. Which macrolide has a better action against mycoplasmas than erythromycin?
    Tylosin
  31. What are the advantages of using an advanced generation macrolide antibiotic?
    • Have high bioavailability following oral administration
    • Broader spectrum of activity
    • Longer half lives
    • Higher tissue concentrations allowing daily dosage
  32. Give an example of a fluroquinolone
    Enrofloxacin, danofloxacin, marbofloxacin, dirofloxacin, orbifloxacin, ibafloxacin
  33. Are the fluoroquinolones bactericidal or bacteriostatic?
    Bactericidal
  34. How do the fluoroquinolones enter bacteria?
    Through porins
  35. Reduction in the permeability of porins to quinolines may confer ...?
    resistance
  36. What is the mechanism of action of the fluoroquinolones?
    They bind to topomerase IV and DNA gyrase inhibiting bacterial DNA replication
  37. Do fluoroquinolones have a narrow or broad spectrum of activity?
    Broad
  38. Are fluoroquinolones highly or lowly orally bioavailable?
    Highly
  39. What type of cell do fluoroquinolones enter?
    Phagocytes
  40. Do fluoroquinolones have high or low protein binding?
    Low
  41. What interferes with the absorption of the fluoroquinolones?
    Aluminium and magnesium antacids
  42. Do fluoroquinolones cross the bbb?
    Most do not (except enrofloxacin)
  43. What organ partially metabolises the fluroquinolones?
    The liver
  44. How are the fluoroquinolones excreted?
    In urine and bile
  45. What are some of the toxic effects associated with fluoroquinolones?
    • Erosion of weight bearing cartilage
    • Clearance of other drugs metabolised in the liver may be reduced
    • Some CNS problems may occur and may be associated with CNS pathology
    • Ocular problems in cats
  46. What is the trade name for enrofloxacin?
    Batril
  47. List the different antiviral drugs
    Amatadine and rimatadine, AZT, Aciclovir, Tamiflu
  48. What is the mechanism of action of Amatadine and rimatadine?  What virus do they treat?
    • Ion channel blockers
    • Influenza A
  49. What is the mechanism of action of AZT?  What virus does it treat?
    • Reverse transcriptase inhibitor
    • Retrovirus
  50. What is the mechanism of action of Aciclovir?  What virus does it treat?
    • DNA polymerase inhibitor
    • Herpes simplex
  51. What is the mechanism of action of Tamiflu?  What virus does it treat?
    • Neuraminidase inhibitor
    • Influenza A and B

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