Drug card 2: anti TB

Question 1

M tuberculosis

Answer 1

Prophylaxis: INH

Treatment: rifampin, INH, pyrazinamide, ethambutol (RIPE; for treatment)

Question 2

M avium-intracellulare

Answer 2

Prophylaxis: azithro

Treatment: azitro, rifampin, ethambutol, streptomycin

Question 3

M leprae

Answer 3

Prophylaxis: N/A

Treatment: long term treatment with dapsone and rifampin for tuberculoid form. Add clofazimine for lepromatous form

Question 4

INH

Answer 4

MOA: decreases synthesis of mycolic acid. Bacterial catalase-peroxidase (KatG) needed to converted INH to active metabolite

Clinical: TB, solo prophylaxis against TB

Toxicity: Neuro, Hepato, + lupus
Vitamin B6 can prevent neurotoxicity
“INH injuires neuron and hepatocytes”

Different INH half lives in fast vs slow acetylators

I=lupus, N=neuro, H=hepato

Question 5

Rifampin

Answer 5

MOA: inhibit DNA dependent RNA pol
Clinical: mycobacterium tuberculosis: delays resistance to dapsone when used for leprosy. Usedfor meningococcal prophylaxis and chemoprophylaxis in contacts with children with H influenza type B.

Toxicity: minor hepatotoxicity, and drug interactions (increase P450); orange body fluid.

Rifampin 4R: 
RNA polymerase inhibitors, 
Revs up microsomal p450, 
Red body fluid, 
Rapid resistance if used alone

Question 6

Pyrazinamide

Answer 6

Mechanism uncertain. Effective in acidic pH phagolysosome where TB gets engulfed by MP

Clinical: TB
Toxicity: hyperuricemia, hepatotoxicity

Question 7

Ethambutol

Answer 7

MOA: decrease carb polymerization of mycobacterial cell wall by blocking arabinosyltransferase.
Clinical: TB
Toxicity: optic neuropathy (red-green color blindness)

Ethambutol for EYES