TB meds-Table 1

Question 1

What is mycobacterium?

Answer 1

Slow-growing, slender rod shaped aerobic with a lipid rich cell wall
Can remain dormant in the host for long periods of time

Question 2

What does mycolic acid do?

Answer 2

Makes up60% of the cell wall of mycobacterium and makes it relatively impermeable to many abx

Question 3

Where can mycobateria reside?

Answer 3

Inside non activated macrophages

Question 4

What is the importance of living in the macrophages?

Answer 4

Creates another permeability barrier

Question 5

What is the defining pathologic feature of TB?

Answer 5

Granuloma mass enclosed by mono, lympho, and neutrophils recruited by an inflammatory response around the foamy macrophages within a fibrous cuff

Question 6

What is the MOA of isoniazid (INH)?

Answer 6

Inhibition of cell wall synthesis by inhibiting mycolic acid synthesis through the formation of reactive oxygen radicals and isonicotinic acid

Question 7

Is INH cidal or static?

Answer 7

Static in the stationary phase and cidal in the rapid dividing phase

Question 8

What metabolizes INH?

Answer 8

N-acetylation and hydrolysis

Question 9

Is there cross-resistance in INH?

Answer 9

No cross resistance to other TB drugs

Question 10

What are the ADRs of INH?

Answer 10

Peripheral neuritis ( B6 def, make sure you supplement)
Hepatitis/hepatotoxic
Inhibits phenytoin met and may produce convulsions in pts prone to seizures

Question 11

What is the most severe side effect of INH? What increase this effect?

Answer 11

Hepatitis/ hepatotoxicity- rifampin and EtOH

Question 12

What is the Black Box warning associated with INH?

Answer 12

Severe and sometimes fatal hepatitis associated with isoniazid therapy may occur and may develop even after many months of tx

Question 13

What are the rifamycins?

Answer 13

Rifampin, rifabutin, rifapentin

Question 14

What is the mechanism of rifampin?

Answer 14

Blocks transcription by interacting with the Bsub unit of bacterial DNA-dependent RNA polymerase

Question 15

Is INH or rifampin have a greater antimicrobial spectrum?

Answer 15

Rifampin

Question 16

Is rifampin static or cidal?

Answer 16

Cidal against gram + and –

Question 17

When is rifampin used prophylactically?

Answer 17

Individuals exposed to meningitis

Question 18

What is rifabutin?

Answer 18

Analog of rifampin active against mycobacterium avium complex but less active against TB

Question 19

What is rifapentin?

Answer 19

Newer, induces 3A4

Question 20

How are the rifamycins administered?

Answer 20

Orally to get to all body fluids and organs

Question 21

What doe the rifamycins induce?

Answer 21

Hepatic mixed function that oxidases increasing its own metabolism as well as other drugs like OCPs

Question 22

How are the rifamycins eliminated?

Answer 22

Feces and urine- may give orange red color

Question 23

What should you warn contact lens wearers about?

Answer 23

Tears may permanently stain soft lenses orange red

Question 24

What are the ADRs of rifamycins?

Answer 24

Minor- N/V

Question 25

What is the MOA of pyrazinamide?

Answer 25

Bactericidal. 1) Enters Mtub by passive diffusion, converted to POA by nicotinamidase/pyrazinamidas (PZase) 2) Inhibits fatty acid synthase I- stops mycolic acid biosynthesis 3) Accumulates w/in acidic environment of macrophages and monocytes and kills tubercle bacilli – help prolong therapy

Question 26

What are the ADRs of Pyrazinamide?

Answer 26

Liver injury with jaundice- rarely fatal

Question 27

What should you do if tx with pyra?

Answer 27

Get liver fxn tests! Shouldn’t tx if they have preexisting liver dysfxn

Question 28

What is the MOA of ethambutol?

Answer 28

Static | Inhibits cell wall synthesis by inhibiting synthesis of polysaccharides and transfer of mycolic acids to the cell wall

Question 29

What is the role of ethambutol?

Answer 29

Helps to prevent the emergence of RIF resistant organisms when primary resistance to INH may be present

Question 30

What are the ADRs of Ethambutol?

Answer 30

Optic neuritis – most imp Diminished visual acuity and loss of green red discrimination – do visual exams Decreases urate excretion – careful if gout