Antimycobacterial drugs

Question 1

Leading infectious killer of people living with HIV/AIDS

Answer 1

TB

*also the leading infectious killer of youth and adults

Question 2

Do we have to report TB to the CDC?

Answer 2

Yep. all cases to State health department (CDC)

Question 3

Environments that TB grows

Answer 3

1. Lungs, skin, other tissues
2. Inside macrophages
3. In cavitary lesions (fastest growth)
4. Closed lesions

Question 4

Is TB treatment safe during pregnancy?

Answer 4

yes

• but all (Isoniazid + rifampin + ethambutol + pyrazinamide) are pregnancy category C: benefits may > risk

Question 5

MOA of INH

Answer 5

Decrease synthesis of mycolic acid

Bacterial catalase peroxidase (encoded by KatG) converts INH to active metabolite.
- resistance is underexpression of KatG and alter inhA

Question 6

Toxicity of INH

Answer 6

Injuries to Nerves and Hepatocytes

• INH gets metabolized by liver E, acetyl transferase, into toxic liver substrates
• Slow acetylators have protective effect?

Question 7

Rifampin MOA

Answer 7

Enters macrophages and inhibits RNA polymerase in TB

Question 8

MOA of ethambutol

Answer 8

Decrease carbohydrate polymerization

By blocking arabinosyltransferase

Question 9

Toxicity of ethambutol

Answer 9

Optic neuropathy: red-green color blindness

“eyethambutol”

Question 10

Toxicity of pyrazinamide

Answer 10

1. Hyperuricemia: gout

2. Hepatotoxicity: liver necrosis

Question 11

Which if the RIPE drugs have good intracellular activity?

Answer 11

Isoniazid

Rifampin

Question 12

Drug tx for leprosy

Answer 12

1. Dapsone + Rifampin
2. Clofazimine if bad

*amithizone can be used in place of dapsone

Question 13

Tx for mycobacterium avium complex (MAC)

Answer 13

Macrolides: clarithromycin + ethambutol +/- rifabutin