Pharm - TB Flashcards
MOA isoniazid
Inhibits mycolic acid synthesis
AE isoniazid
- Hepatitis
- Inhibit CYP450
- Peripheral neuropathy
Interactions INH
- Aluminum antacids decrease absorption
- Inhibits cortisol metabolism
- GC’s decrease INH blood levels
What supplementation should to be given to pt on INH?
B6/pyridoxine = competes with pyridoxal phosphate, causing peripheral neuropathy
MOA rifampin
Inhibits DNA-dep RNA polymerase by binding Beta-subunit
AE rifampin
- Rust colored bodily fluids
2. CYP450 induction
Interactions rifampin
Probenecid increases rifampin levels; important since EMB and PZA can cause hyperuricemia so TB pt likely to need gout meds
MOA ethambutol
Inhibits arabinosyl transferase = inhibits cell wall synthesis
AE EMB
- Optic neuritis
2. Hyperuricemia
Interactions EMB
Aluminum antacids decrease EMB absorption
MOA pyrazinamide
Converted to pyrazinoic acid, decreasing pH below what is favorable for growth of TB
AE pyrazinamide
- Hepatitis
- Hyperuricemia
- Myaglia
MOA cycloserine
Analog of D-ala; inhibits L-ala racemase and D-ala synthetase
AE cycloserine
- Suicidal ideations
- Seizures
- Depression
CI cycloserine
Epilepsy
MOA ethionamide
Analog of INH; inhibits protein synthesis
AE ethionamide
- GI
- Neuro
- Hepatotoxicity
What supplementation should be given with ethionamide?
B6 - remember it’s an INH analog
MOA capreomycin
Unknown
AE capreomycin
- Nephrotoxicity
2. Ototoxicity
Which TB drug can be used alone?
Ethionamide
Which TB drugs require concomitant B6?
INH and ethionamide
Which TB drugs cross CSF and placenta?
INH, EMB, PZA, cycloserine
Which TB drugs should you avoid with antacids?
INH, EMB
Which TB drugs are both bacteriocidal and bacteriostatic?
INH
PZA
Cycloserine
Ethionamide
Only bacteriocidal?
RIF
Only bacteriostatic?
EMB
Capreomycin
Rifampin vs. rifapentine
Rifapentine has longer T1/2 = once weekly dosing
Also less induction of CYP450
Rifampin v. rifabutin
Rifabutin has least induction of CYP of the rafamycins
Which TB drug is N-acetylated?
INH
Resistance to RIF develops because of:
Change in beta-subunit of DNA-dep RNA polymerase
Which TB drug necessitates back up birth control?
RIF (remember it INDUCES CYP450 = lower OC blood levels)
Active TB must be treated for a minimum of:
24 weeks
Latent vs. active TB tx
Latent = 3 months of INH + rifapentine Active = 24 weeks of RIPE or RIPS
What is CI for tx of LTBI?
RIF + PZA due to liver toxicity