TB meds-Table 1 Flashcards Preview

Pharm3- fixed > TB meds-Table 1 > Flashcards

Flashcards in TB meds-Table 1 Deck (30):
1

What is mycobacterium?

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

2

What does mycolic acid do?

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

3

Where can mycobateria reside?

Inside non activated macrophages

4

What is the importance of living in the macrophages?

Creates another permeability barrier

5

What is the defining pathologic feature of TB?

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

6

What is the MOA of isoniazid (INH)?

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

7

Is INH cidal or static?

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

8

What metabolizes INH?

N-acetylation and hydrolysis

9

Is there cross-resistance in INH?

No cross resistance to other TB drugs

10

What are the ADRs of INH?

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

11

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

Hepatitis/ hepatotoxicity- rifampin and EtOH

12

What is the Black Box warning associated with INH?

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

13

What are the rifamycins?

Rifampin, rifabutin, rifapentin

14

What is the mechanism of rifampin?

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

15

Is INH or rifampin have a greater antimicrobial spectrum?

Rifampin

16

Is rifampin static or cidal?

Cidal against gram + and –

17

When is rifampin used prophylactically?

Individuals exposed to meningitis

18

What is rifabutin?

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

19

What is rifapentin?

Newer, induces 3A4

20

How are the rifamycins administered?

Orally to get to all body fluids and organs

21

What doe the rifamycins induce?

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

22

How are the rifamycins eliminated?

Feces and urine- may give orange red color

23

What should you warn contact lens wearers about?

Tears may permanently stain soft lenses orange red

24

What are the ADRs of rifamycins?

Minor- N/V

25

What is the MOA of pyrazinamide?

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

26

What are the ADRs of Pyrazinamide?

Liver injury with jaundice- rarely fatal

27

What should you do if tx with pyra?

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

28

What is the MOA of ethambutol?

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

29

What is the role of ethambutol?

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

30

What are the ADRs of Ethambutol?

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