TB Agents

Question 1

What are the first line TB agents

Answer 1

Isoniazid, Rifampin, Pyrazinamide, ethambutol

Question 2

When using a multidrug regimen using the first line TB agents which one can be dropped earliest

Answer 2

Ethambutol

Question 3

What is the MOA to isoniazid

Answer 3

inhibit mycolic acid (fatty acid in cell membrane) by forming NAD-adducts, the NAD-adducts blocks the Inh-A coenzyme binding site

Question 4

How does resistance occur to isoniazid, what changes

Answer 4

katG, enzyme to active isoniazid is no longer functioning/ inhA, mutations in NADH binding site

Question 5

What is the toxicity associated with isoniazid

Answer 5

peripheral nephritis if not given with vitamin B6 (pyridoxine), hepatoxicty

Question 6

What is the MOA of rifampin

Answer 6

inhibits RNA polymerase by binding to the beta subunit therefore inhibiting initiation of transcription

Question 7

T/F: The use of rifampin will lead to inhibiton of liver enzymes

Answer 7

False: The use of rifampin will lead to induction of liver enzymes

Question 8

What is a rifampin derivative used in TB coinfection with what disease, when is it used

Answer 8

Rifabutin/ patients with a TB/HIV co-infection when using a protease inhibitor, M. avium-intracellulare infection

Question 9

Which rifampin derivative has a longer half life and is dosed once weekly in the continuation phase

Answer 9

Rifapentine

Question 10

What is the enzyme that converts pyrizinamide into its active form, what is the active form

Answer 10

Pyrazinamidase (pncA), pyrazinoic acid

Question 11

What is the toxicity associated with pyrazinomide

Answer 11

Heptatoxicty

Question 12

What is the MOA of ethambutol

Answer 12

inhibits arabinsoyl transferase affecting synthesis of arabinoglactan and liproarabinomannan in cell wall

Question 13

What are the toxicities associated with ethambutol

Answer 13

Optic neuritis

Question 14

T/F: None of the first line TB drugs are prodrugs that need to be coverted by TB

Answer 14

False: Pyrazinomide and Isoniazid both need to be converted to their active forms by TB in order to work

Question 15

What are the second line TB agents

Answer 15

Fluroquinolones, oxazolidinones, diarylquinolones

Question 16

What are the fluroquinolones used against TB

Answer 16

Levofloxacin, moxifloxacin, gatifloxacin

Question 17

What is the oxazolidinones used against TB, diarylquinolones

Answer 17

Linezolid, Bedaquiline

Question 18

What is the MOA of fluroquinolones

Answer 18

inhibit DNA gyrase therefore not allowing uncoiling

Question 19

What is a serious side effect of fluroquinolones

Answer 19

aortic rupture

Question 20

What are the reasons to bring in new drugs to fight TB

Answer 20

Reduce treatment duration, Succesful treatment against drug resistant TB , cure latent TB infection

Question 21

T/F: Linezolid inhibits protein synthesis

Answer 21

True

Question 22

What are the side effects associated with linezolid use

Answer 22

various neuropathies and myelosuppresion

Question 23

T/F: Nitroaromatics are prodrugs and could be brought to first line over time

Answer 23

True

Question 24

T/F: Bedaquiline is active against ATP synthase and works well against persistent TB

Answer 24

True

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Question 25

What are the side effects of bedaquiline

Answer 25

Q-T interval prolongation, hepatotoxicity

Question 26

What are the third line agents of TB

Answer 26

Imipenem, Clofazimine, Clarithromycin, Thioridazine

Question 27

If someone has latent TB what are the treatment options and how long are they

Answer 27

Isoniazid alone 9 months, Rapamacin alone 4 months, isoniazid and rifapentene weekly for 3 months

Question 28

What should be done if there is a single drug resistance to a first line drug in active TB, what is the active TB is resistant to rifampicin

Answer 28

Replace with fluroquinolone, extend to 12 months

Question 29

T/F: If a patient has a HIV/TB co-infection they should recieve the standard regimen

Answer 29

False: If the patient is receiving anti-retroviral therapy than the standard regimen should be used, if the patient is not receiving anti-retroviral therapy than the continuation phase should be extended by 3 months

Question 30

What rapamycin derivative should be used if the patient has HIV as well, why

Answer 30

Rifabutin to reduce CYP 450 induction

Question 31

What sickness can occur when treating TB in patients with HIV due to their immune system being restored, what drugs will treat IRIS

Answer 31

Immune Reconstitution Inflammatory Syndrome (IRIS)/ mild-ibuprofen, severe- corticosteroids

Question 32

What are the two main organisms that cause tuberculosis besides M. tuberculosis

Answer 32

M. avium and M. abscessus

Question 33

What is a way to have resistance against pyrazinamide

Answer 33

PncA mutation

Question 34

What are resistance mechanisms against ethambutol

Answer 34

Overexpression of embA, embB, or embC/ mutations in embB

Question 35

T/F: Mutations in gyrA can lead to fluroquinolone resistance

Answer 35

True