TB drugs

Question 1

Should you use a multi-drug therapy for treating active Tb?

Answer 1

yes

• enhance rates of response/cure
• reduce emergence of resistance

Question 2

Can isoniazid HCl (INH) be used alone?

Answer 2

not used as a single drug to treat TB

-usually in combo with at least 2 other drugs

Question 3

What are two ways that there can be resistance against Isoniazid HCl (INH)

Answer 3

1. Mutations in katG gene
   - catalase-peroxidase–>INH activation
2. Mutation of inhA gene–>cell wall (mycolic acid) synthesis

Question 4

Can rifampin be used alone?

Answer 4

no because of rapid development of resistance

Question 5

What are the mechanisms of resistance for rifampin?

Answer 5

inhibits DNA dependent RNA polymerase, encoded by the rpoB gene
-rpoB mutations can cause rifampin resistance

Question 6

Does rifampin interact with other drugs? How?

Answer 6

yes
it induces hepatic microsomal enzymes
-accelerates the clearance and reduces effective serum concentrations
-coumadin, estrogen, anti convulsants, antiretroviral drugs

Question 7

What are two toxicities ethambutol can cause?

Answer 7

optic neuritis-blurred vision, central scotomata, red-green color vision loss, dose-related

peripheral neuropathy less common-feet, hands

Question 8

What is ethambutol?

Answer 8

first like tb helper drug

Question 9

Pyrazinamide is used for how long?

Answer 9

first line drug used for the 1st two months of therapy

Question 10

What is primary resistance?

Answer 10

infection by a source case with drug-resistant tb

acquired at infection

Question 11

What is secondary resistance?

Answer 11

from ineffective therapy
-too few drugs to prevent emergence of resistance
suboptimal drug dosing or absorption–>selection for resistnace

Question 12

The risk of evolution of resistance to two drugs is what of the risk of the development of each drug?

Answer 12

product

you add them

Question 13

What is multidrug resistant TB?

Answer 13

resistant to both INH and rifampin

• more common in HIV
• nosocomial transmission and high mortality in HIV/AIDS

Question 14

What does not being able to use rifampin do to duration of therapy?

Answer 14

eliminates short-course (6 month) TB therapy

–>requires at least 18-24 months

Question 15

What is extensively resistant TB?

not on list

Answer 15

resistant to all the following:
INH and rifampin
fluoroquinolone
one of three injectable antibiotics (amikacin, kanamycin, capreomycin)

Question 16

What is the 6 month treatment regimen of Tb treatment?

Answer 16

RIPE
R=rifampin
I=INH
P=PZA
E-Ethaambutol

Initial phase=RIPE
Constitutional phase=RI (Emb not needed if pan-sucept.)

*can’t do the six month therapy without rifampin

Question 17

Do you need DOT with intermittent therapy (2-3 times per week)?

Answer 17

yes

Question 18

What drugs are only effective for NTM?

Answer 18

clarithro and azithro

Question 19

What drugs are only effective for TB and not NTM?

Answer 19

INH and PZA

Question 20

What drugs are effective for both TB and NTM?

Answer 20

Rif, Emb, FQ, AG (aminoglycosides)

Question 21

Are the treatments the same in leprosy as in Tb?

Answer 21

no very different treatments !