Tuberculosis Meds

Question 1

Differentiate active TB from latent TB

Answer 1

Latent: consolidated bacteria in the lungs is encapsulated by macrophages
Active: coughing up active bacteria that escaped the macrophages’ capsule

Question 2

What patients are at highest risk for developing active TB

Answer 2

Immunosuppressed patients (HIV)

Question 3

What are the signs and symptoms of active TB?

Answer 3

Hemoptysis, malaise, fatigue, weight loss, night sweats, fever

Question 4

T/F: Patients with latent TB can transmit TB to others.

Answer 4

False

Question 5

What is the lifetime risk of developing active TB for both healthy individuals and in HIV patients that have latent TB?

Answer 5

10% lifetime risk in healthy people

10% per year in HIV patients

Question 6

Define and describe MDR TB.

Answer 6

Multiple Drug Resistant TB: resistance to the two main drugs - isoniazid and rifampin

Question 7

Name and describe the pathogen responsible for TB.

Answer 7

Mycobacterium TB - acid fast bacillus that is slow growing (long time to culture) and settles primarily in the apical portion of the lungs

Question 8

Describe the findings of the Purified Protein Derivative (PPD) Skin Test

Answer 8

• 15+ mm induration: patient has latent TB
• 10 - 15 mm induration: high risk patient considered to have latent TB
• 5 - 10 mm induration: immunocompromised or known contact with active TB considered to have latent TB

Question 9

Aside from the PPD skin test, what is another form of screening for TB?

Answer 9

IGRA blood test used to diagnose latent TB

Question 10

What is the disadvantage of using the IGRA blood test in screening TB?

Answer 10

Cost –> more expensive than PPD skin test

Question 11

What diagnostic tests are used in the identification of TB?

Answer 11

chest X-ray, MTB PCR, and AFB smear

Question 12

How is a pregnant patient treated for TB?

Answer 12

No different other than avoiding streptomycin

Question 13

How is meningeal TB treated differently than pulmonary TB?

Answer 13

Add dexamethasone (crosses BBB well) to other common TB meds

Question 14

What are the key principles of treating TB?

Answer 14

• Kill large volume of bacteria
• Treat persisters –> TB stays in the body for a long time
• Prevent resistance
• Ensure highest level of adherence (DOT = directly observed therapy)

Question 15

What are the two phases of drug therapy in TB?

Answer 15

Intensive: 3-4 drugs for 4 months
Continuation: 2 drugs for 2 months

Question 16

List the drugs in the 4-drug regimen for treatment of TB.

Answer 16

R - Rifampin
I - Isoniazid
P - Pyrazinamide
E - Ethambutol

Question 17

Which drug is used most commonly in the treatment of TB?

Answer 17

Isoniazid

Question 18

Which TB treatment drug is known as the original antidepressant?

Answer 18

Isoniazid

Question 19

Describe the mechanism of action of isoniazid relative to the treatment of TB.

Answer 19

Reduces formation of mycolic acid found in the cell wall of mycobacterium

Question 20

State whether isoniazid is hydrophilic or lipophilic and how is it clinically relevant.

Answer 20

It is highly lipophilic meaning it has a high volume of distribution –> crosses BBB.

Question 21

What are the significant AEs associated with isoniazid?

Answer 21

Hepatotoxic –> monitor LFTs and patient cannot drink alcohol
Increases excretion of vitamin B6 (pyridoxine) –> low B6 leads to peripheral neuropathy

Question 22

What other drug is always given in combination with isoniazid?

Answer 22

Pyridoxine to supplement B6

Question 23

Why is rifampin not used by itself to treat TB?

Answer 23

It quickly develops resistance

Question 24

T/F: Rifampin has a lot of drug-drug interactions.

Answer 24

True: It is a potent CP-450 inducer –> it will cause other drugs to be metabolized faster

Question 25

Describe the advantages and disadvantages of rifabutin in the treatment of TB.

Answer 25

Advantage: Less potent inducer of CP-450 –> fewer drug interactions
Disadvantage: Expensive

Question 26

How is rifampin used to treat other diseases?

Answer 26

As adjunctive or prophylactic therapy for leprosy, staph aureus endocarditis, and neisseria meningitis

Question 27

What are two significant AEs of rifampin?

Answer 27

Causes minor increase in LFTs –> caution when used in combination with Isoniazid
Orange discoloration of sweat, tears, sputum

Question 28

Describe the mechanism of action of pyrazinamide.

Answer 28

Creates an acidic intracellular environment destructive to bacterium

Question 29

What is the significant AE associated with pyrazinamide?

Answer 29

Arthralgias and increased uric acid –> caution in gout

Question 30

T/F: Pyrazinamide can be used effectively to treat meningeal TB.

Answer 30

True: It is absorbed well into the CNS

Question 31

T/F: Ethambutol is hepatotoxic.

Answer 31

False: It is renally eliminated

Question 32

What is the significant AE associated with ethambutol?

Answer 32

Optic neuritis –> ophthalmology consult before starting drug

Question 33

What is the first clinical indication that a patient is being affected by ethambutol’s significant AE?

Answer 33

Red/green color blindness

Question 34

Which aminoglycoside can be used in the treatment of TB?

Answer 34

Streptomycin

Question 35

What significant AEs are associated with streptomycin?

Answer 35

Nephrotoxicity and Ototoxicity

Question 36

When is streptomycin used in the treatment of TB?

Answer 36

Rare –> mostly used in cases of resistance to first line (RIPE) agents

Question 37

What drugs can be used to treat latent TB?

Answer 37

Isoniazid: qd for 6 - 9 months
Rifampin: qd x 4 months