Anti-Tb Drugs

Question 1

What is the average range of treatment for Tb?

Answer 1

6mos-2yrs

Question 2

Why is combination therapy used in the treatment of Tb?

Answer 2

Prevent resistance

Question 3

What are the first line TB meds?

Answer 3

RIPE
Rifampin 
Isoniazid (INH)
Pyrazinamide
Ethambutol 
(Streptomycin can also be used)

(~2months into treatment can drop pyrazinamide and ethambutol)

Question 4

Second-line TB agents include:

Answer 4

Aminoglycosides(amikacin, kanamycin)
Moxifloxacin, levofloxacin (fluroquinolones)
Capreomycin
Cycloserine
p-aminosalicylic acid
Ethionamide

Question 5

Isoniazid’s MOA:

Answer 5

Inhibits cell wall synthesis by inhibiting synthesis of mycolic acid an important component of mycobacteria cell wall

Question 6

AEs of isoniazid:

Answer 6

Hepatotoxicity(esp in slow acetylators)

Neurotoxicity

Question 7

How can the neurotoxicity associated with isoniazid by prevented?

Answer 7

Vit B-6

Question 8

Two main indications for isoniazid:

Answer 8

Active TB (with other first line agents)
Latent TB infection (given alone with vit B 6)

Question 9

What is Rifampin’s MOA?

Answer 9

Inhibit DNA-dependent RNA polymerase

not specific to mycobacteria, also treats S.Aureus, MRSA w/ other agents

Question 10

What should patients be counseled about when prescribed rifampin related to body secretions?

Answer 10

All secretions will impart a red-orange color

Question 11

AE associated with rifampin:

Answer 11

Hepatotoxicity

Question 12

DIs of rifampin:

Answer 12

Significantly induces CYP450 and glucorinidation enzymes= decr. efficacy of other drugs

(In pts with HIV that are taking a protease inhibitor the drug levels will plummet, need to switch to another HIV drug or change rifampin to rifabutin)

Question 13

What is an advantage of using rifabutin?

Answer 13

Still a rifamycin but has less drug interactions than rifampin.
Is metabolized by CYP3A4

Question 14

AE associated with rifabutin include:

Answer 14

Neutropenia, uveitis

Question 15

What is ethambutol’s MOA?

Answer 15

Inhibits cell wall synthesis, by inhibiting incorporation of mycolic acids into the mycobacterial cell wall

Question 16

Patients taking ethambutol need regular ______ exams d/t the risk for _______ .

Answer 16

eye

optic neuritis

Question 17

Ethambutol is the only first line TB agent that is ______ eliminated.

Answer 17

renally

Question 18

The MOA of pyrazinamide is unclear but it is bacterio______.

Answer 18

cidal

Question 19

Why should pyrazinamide never be used alone?

Answer 19

Resistance to the drug develops rapidly

Question 20

Which type of patients should you use caution with when prescribing pyrazinamide?

Answer 20

Patients with gout, pyrazinamide’s metabolite causes hyperuricemia

Question 21

AE of pyrazinamide:

Answer 21

Hepatotoxicity

Question 22

What deems TB, MDR-TB?

Answer 22

Resistance to INH and rifampin

Question 23

What deems TB, XDR-TB?

Answer 23

Resistance to INH, rifampin, and any fluroquinolone and one second line injectable (ex-amikacin)

Question 24

How does resistance to TB drugs occur?

Answer 24

Transmitted resistant TB
Non-adherence
Inappropriate or incomplete treatment

Question 25

Bedaquiline(Sirturo) was recently approved for treatment of MDR TB in patients with no other options. What is its MOA and Black box warning?

Answer 25

MOA: Inhibits enzyme essential to produce energy (ATP)

Black Box: QT prolongation