Antimycobacterials Flashcards
M tuberculosis
Prophylaxis: isoniazid
tx: Rifampin, Isoniazid, Pyrazinamide, Ethambutol (RIPE)
M avium-intracellulare
Prophylaxis: Azmycin, rifabutin
Tx: Azmycin + ethambutol
M leprae
tx: dapsone and rifampin for tuberculoid form
add clofazimine for lepromatous form
Rifampin MOA
inhibit DNA-dependent RNA polymerase
Rifampin use
M. tuberculosis; delays resistance to dapsone when used for leprosy.
used for meningococcal prophylaxis and chemoprophylaxis in contacts of children with H. influenzae B
4Rs of Rifampin
RNA polymerase inhibitor
Ramps up microsomal P450
Red/orange body fluids
Rapid resistance if used alone
Rifampin ADR
minor hepatotoxicity and drug interactions, orange body fluids
rifamycin in HIV use
rifabutin favored over rifampin due to less cyp450 stimulation
rifampin mech of resistance
mutations reduce drug binding to RNA polymerase. monotherapy rapidly leads to resistance
Isoniazid MOA
dec synthesis of mycolic acids.
Bacterial catalase-peroxidase (encoded by KatG) needed to convert INH to active metabolite
Isoniazid use
TB only agent used as solo prophylaxis tx
isoniazid ADR
hepatoxicity, p-450 inhibition, drug-induced SLE, vit b6 deficiency (peripheral neuropathy, sideroblastic anemia).
Admin w/ vit b6
isoniazid mech. of resistance
mutations leading to underexpression of KatG
pyrazinamide MOA
mechanism uncertain
prodrug converted to pyrazinoic acid.
works best at acidic pH
pyrazinamide use
TB
