ID: Sulfonamides

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Author:
mwill222
ID:
128751
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ID: Sulfonamides
Updated:
2012-01-19 10:49:19
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pharmacy infectious disease
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Description:
Spring 2012 PT Module IV- Sulfonamides
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  1. Sulfonamides are considered Bacterio________.
    Which means?
    Static: They DO NOT KILL the bacteria, they stop the bacteria from proliferating
  2. What are sulfonamides structually similar to?
    PABA
  3. Sulfonamides are often used _____________________ with other drugs.
    synergistically
  4. What are the pros of synergism?
    • lower concentration of drug used
    • broader spectrum
    • reduces drug resistance
  5. What infection are sulfonamides most commonly used in treating?
    UTI's
  6. How were sulfonamides fisrt discovered?
    • Gerhard Domagk and bright red dye (Prontosil) in mice
    • azo functional group was reduced in vivo
  7. Why are there only about a dozen sulfonamides used worldwide instead of thousands?
    • sulfonamide toxicity in some patients
    • resistant bacterial strains because of early indiscriminant use
  8. What are the risks of using an unprotected sulfonamide with a high pKa value?
    • Form into sodium salt
    • Becomes supersaturated n urine
    • crystals begin to form (crystalluria)
  9. How do you avoid chemically avoid crystalluria with sulfonamides?
    • Attach heterocyclic rings to lower pKa (ionized-water soluble)
    • Use more than one type of sulfonamide (amount of each does not reach threshold amt to form crystals)
  10. What did earliest sulfonamides lead to crystallization and kidney damage?
    • poor water solubility
    • molecules were unionzed at urine pH
  11. Sulfonamides are partially deactivated by __________________ & ___________________.
    • acetylation
    • glucuronidation
    • (metabolized because of increased levels of enzyme---polarized and cleared quickly)
  12. Because sulfonamides are similar to PABA they are considered a ____________________.
    Antimetabolite
  13. What is the mechanism of sulfonamides?
    • competitive inhibitors of PABA
    • prevent synthesis of Dihydrofolic acid
    • inhibits mechanism of DNA synthesis
  14. What is the mechanism of Folate Reductase Inhibitors (Trimethoprim)?
    • Folate reductase inhibitor
    • prevents synthesis of Tetrahydrofolic acid
  15. Why may Trimethoprim cause side effects?
    there is some affinity for human folate reductase
  16. Why does the inhibtion of folate synthesis stop infection?
    Microbes CANNOT use dietary folic acid
  17. The blocking of two points in the folate pathway is called _______________________.
    sequential blockade
  18. When is trimethoprim used clinically as a single agent?
    oral treatment of uncomplicated UTIs
  19. What is the fixed ratio of sulfamethoxazole to trimethoprim?
    5 to 1
  20. What are the 2 main reasons to use the combination of TMP-SMZ?
    • synergistic in vitro
    • less likely to induce bacterial resistance than either used alone
  21. What enzyme does does sulfamethoxazole block?
    dihydropteroate synthase
  22. What enzyme does trimethoprim block?
    dihydrofolate reductase
  23. What are the 3 major indications for SMZ-TMP?
    • UTIs
    • Pneumocystic carinii pneumonia
    • otitis media
  24. In what patients should use caution with SMZ-TMP?
    renal/ hepatic failure
  25. What drugs action can increased due to the increased inhibition of hepatic metabolism by SMZ-TMP?
    phenytoin
  26. What substrates synthesis is inhibited by SMZ-TMP thus preventing DNA synthesis?
    deoxythymidine
  27. _________ are essential intermediates for synthesis of DNA bases.
    Folates
  28. Most susceptible bacteria to SMZ-TMP synthesize their own ____________.
    folic acid
  29. What is the standard spectrum activity of SMZ-TMP?
    • bacteriostatic
    • gram (-)
    • H. influenza is becoming resistant (40-50%)
    • some staph and strep coverage

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