Medicine & USMLE


Antibiotics / Antiparasitics
  1. Penicillin Overview
  2. Penicillinase-Sensitive vs. Penicillinase-Resistant Penicillins
  3. Anti-Pseudomonal Penicillins
  4. Cephalosporins Overview
  5. 1st Generation Cephalosporins
  6. 2nd Generation Cephalosporins
  7. 3rd Generation Cephalosporins
  8. 4th Generation Cephalosporins
  9. 5th Generation Cephalosporins
  10. Carbapenems
  11. Monobactams (Aztreonam)
  12. Vancomycin
  13. Aminoglycosides
  14. Tetracyclines
  15. Tigecycline
  16. Chloramphenicol
  17. Clindamycin
  18. Linezolid
  19. Macrolides
  20. Polymyxins
  21. Sulfonamides
  22. Dapsone
  23. Trimethoprim
  24. Fluoroquinolones
  25. Daptomycin
  26. Metronidazole
  27. Rifamycins (Rifampin, Rifabutin)
  28. Isoniazid
  29. Pyrazinamide
  30. Ethambutol
  31. Chloroquine


Pyrazinamide is an antibiotic used to treat active tuberculosis. Its exact mechanism is unknown, but it is thought to be active in macrophagic phagolysosomes, which play an important role in the pathogenesis of tuberculosis.  Adverse effects of pyrazinamide use include hepatotoxicity, which can manifest with jaundice, liver tenderness, and elevated liver enzymes. Hyperuricemia and gout are also side effects seen with the drug.

Key Points

  • Pyrazinamide (PZA)
    • Mechanism
      • Exact mechanism is unknown
        • Activated by conversion to pyrazinoic acid by the mycobacterial enzyme pyrazinamidase
        • Thought to be more active at acidic pH (e.g. in macrophage phagolysosomes)
    • Clinical Use
      • Mycobacterium tuberculosis
        • Part of RIPE regimen of rifamycin, isoniazid, pyrazinamide, and ethambutol
    • Adverse Effects
      • Hepatotoxicity
        • Dose-dependent hepatotoxicity that is synergistic with rifampin’s hepatotoxic effect (also in RIPE treatment for TB)
        • Manifests as increased AST/ALT, jaundice, and liver tenderness
      • Hyperuricemia/Gout
        • Pyrazinamide competes with uric acid for secretion by the kidneys, resulting in increased uric acid levels
      • Arthralgias