Pharmacology - Macrolides 1

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Pharmacology - Macrolides 1
2014-01-29 20:51:39
Pharmacology Macrolides
Pharmacology - Macrolides 1
Pharmacology - Macrolides 1
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  1. What type of bacteria are macrolides mainly active against?
    G+ aerobes (some G-)
  2. What are macrolides mainly used to treat?
    Upper and lower GI infections (Chlamydia/traveler’s diarrhea)
  3. Are macrolides bacteriostatic or bactericidal?
  4. What is the MOA for macrolides?
    Protein synthesis inhibitor (50S ribosome) by inhibition of the translocation step of the peptidyl tRNA to the peptidyl donor site
  5. Why is erythromycin best absorbed in alkaline media?
    Neutral at alkaline pH: It has an amine group that carries a positive charge in acidic media, limiting absorption
  6. Why should you not use chloramphenicol, macrolides or clindamycin together?
    They are antagonistic because they all bind at the same site
  7. What organisms are sensitive to Erythromycin?
    Legionella pneumophilla, Chlamidiae, Mycoplasma pneumonia, some G+ and G- cocci, Bordatella pertussis
  8. Why has there been a resurgence of whooping cough?
    The old vaccine caused rashes/reactions, so it went out of use and the new vaccine isn’t as effective
  9. Are macrolides considered broad or narrow spectrum?
    Pretty broad
  10. Are Macrolides any good against Staph infections?
  11. Are Macrolides useful against Streptococcus pneumoniae?
    Yes, but a lot of resistance has emerged
  12. Why can’t penicillins treat all the same bacteria as Macrolides?
    Because the bacteria macrolides treat often do not have a cell wall
  13. Azithromycin is better at treating G- or G+ bacteria?
  14. Erythromycin is better at treating G+ or G- bacteria?
  15. What is Bordatella pertussis?
    Whooping cough
  16. Why is erythromycin administered in a protected tablet or capsule?
    Because it is destroyed by stomach acid
  17. What form of erythromycin have better absorption?
    Ester forms (stearate and ethylsuccinate, lactobionate), because they protect it from stomach acid
  18. What is the half-life for erythromycin?
    1.5 hours
  19. Erythromycin penetrates which tissues?
    Most tissues, except brain and CSF (too big to enter)
  20. How is erythromycin metabolized?
    By CYP450, mainly 3A4
  21. What are the main adverse reactions to erythromycin?
    Fever, eosinophilia, skin lesions, allergic reactions, GI issues, Thrombophlebitis (IV), transient auditory impairment (large doses), cholestatic jaundice (estolate form), Acute cardiac arrhythmias, prolonged QT interval
  22. What is eosinophilia?
    Aggregation of eosinophils (WBCs)
  23. What DDIs does erythromycin have?
    Interferes with metabolism of carbamazepine, corticosteroids, warfarin and theophylline and drugs normally metabolized by CYP3A4
  24. What change in pharmacokinetics would you likely observe in a patient who is taking erythromycin with other CYP3A4 metabolized drugs?
    Higher drug concentrations
  25. What are the indications for Erythromycin?
    Legionnaire’s disease, Pneumonia caused by Strep, Chlamydia, mycoplasma, other Strep infections, prophylaxis for reheumatic fever or strep infection with damaged heart valve
  26. If a patient is allergic to penicillins, would you use erythromycin instead?
    Maybe, usually CPNs first, but could use erythromycin
  27. Which drugs make up the Macrolides?
    Erythromycin, Azithromycin and Clarithromycin
  28. Which macrolides are used most frequently: Erythromycin, Azithromycin or Clarithromycin and why?
    Azithromycin and Clarithromycin due to fewer complications than erythromycin
  29. How does Clarithromycin differ from Erythromycin?
    Addition of a Methyl group
  30. Which drug is considered slightly better Azithromycin or Clarithromycin?
    Azithromycin, though they have similar characteristics
  31. What percent of Clarithromycin is absorbed in the GI tract?
  32. What is the half like of Clarithromycin?
    6 hours
  33. Does Clarithromycin need to have an enteric coating for oral administration?
    No, not acid labile
  34. How is Clarithromycin metabolized?
  35. In what tissues would you expect to get high concentrations of clarithromycin?
    Most tissues, including the inner ear and lung