Flashcards in TB drugs Deck (21):
Should you use a multi-drug therapy for treating active Tb?
-enhance rates of response/cure
-reduce emergence of resistance
Can isoniazid HCl (INH) be used alone?
not used as a single drug to treat TB
-usually in combo with at least 2 other drugs
What are two ways that there can be resistance against Isoniazid HCl (INH)
1. Mutations in katG gene
2. Mutation of inhA gene-->cell wall (mycolic acid) synthesis
Can rifampin be used alone?
no because of rapid development of resistance
What are the mechanisms of resistance for rifampin?
inhibits DNA dependent RNA polymerase, encoded by the rpoB gene
-rpoB mutations can cause rifampin resistance
Does rifampin interact with other drugs? How?
it induces hepatic microsomal enzymes
-accelerates the clearance and reduces effective serum concentrations
-coumadin, estrogen, anti convulsants, antiretroviral drugs
What are two toxicities ethambutol can cause?
optic neuritis-blurred vision, central scotomata, red-green color vision loss, dose-related
peripheral neuropathy less common-feet, hands
What is ethambutol?
first like tb helper drug
Pyrazinamide is used for how long?
first line drug used for the 1st two months of therapy
What is primary resistance?
infection by a source case with drug-resistant tb
(acquired at infection)
What is secondary resistance?
from ineffective therapy
-too few drugs to prevent emergence of resistance
suboptimal drug dosing or absorption-->selection for resistnace
The risk of evolution of resistance to two drugs is what of the risk of the development of each drug?
you add them
What is multidrug resistant TB?
resistant to both INH and rifampin
-more common in HIV
-nosocomial transmission and high mortality in HIV/AIDS
What does not being able to use rifampin do to duration of therapy?
eliminates short-course (6 month) TB therapy
-->requires at least 18-24 months
What is extensively resistant TB?
not on list
resistant to all the following:
INH and rifampin
one of three injectable antibiotics (amikacin, kanamycin, capreomycin)
What is the 6 month treatment regimen of Tb treatment?
Constitutional phase=RI (Emb not needed if pan-sucept.)
*can't do the six month therapy without rifampin
Do you need DOT with intermittent therapy (2-3 times per week)?
What drugs are only effective for NTM?
clarithro and azithro
What drugs are only effective for TB and not NTM?
INH and PZA
What drugs are effective for both TB and NTM?
Rif, Emb, FQ, AG (aminoglycosides)