Antimycobacterial drugs Flashcards
M. tuberculosis (Prophy/Tx)
P: Isoniazid
T: RIPES - rifampin, isoniazid, pyrazinamide, ethambutol, streptomycin
M. avium-intracellulare (Prophy/Tx)
P: Azithromycin
T: Azythromycin, rifampin, ethambutol, streptomycin
M. leprae (Prophy/Tx)
P: none
T: Long-term Tx = dapsone & rifampin (tuberculoid form)
Add clofazimine for lepromatous form
Isoniazid MECH
decreased synth of mycolic acid. Bacterial catalase-peroxidase (KatG) needed to convert INH to active metabolite. (INH - injures neurons & hepatocytes)
Isoniazid USE
Mycobacterium tuberculosis. The only agent used as solo prophy against TB.
Different INH half-lives in fast v. slow acetylators
Isoniazid TOX
Neurotox, hepatotox. Give pyridoxine (B6) to prevent neurotox & lupus
Rifampin MECH
Inhibits DNA-dependent RNA pol.
Rifampin USE
Mycobacterium tb; delays resistance to dapsone when used for leprosy. Meningococcal prophy & chemoprophy in contacts of children w/H. flu type B
Rifampin TOX
Minor hepatotox & drug interactions (increase P450), orange body fluids
Rifampin R’s
RNA polymerase inhibitor
Revs up microsomal P450
Red/orange body fluid
Rapid resistance if used alone
Pyrazinamide MECH
Mechanism uncertain. Thought to acidify intracellular environment via conversion to pyrazinoic acid. Effective in acidic pH of phagolysosomes, where TB engulfed by mac.phages is found.
Pyrazinamide USE
Mycobacterial tb
Pyrazinamide TOX
Hyperuricemia, hepatotox
Ethambutol MECH
decreased carb polymerization of mycobacterium cell wall by blocking arabinosyltransferase.
Ethambutol USE
Mycobacterium tb
