Antimycobacterial

Question 1

Combination drug therapy

Answer 1

First 2 months: rifampin + isoniazid + pyrazinamide

Next 4 months: rifampin + isoniazid

Question 2

MOA of isoniazid (INH)

Answer 2

Bactericidal
Site of action: intra & extracellular bacilli
Inhibits mycolic acid synthesis

Question 3

INH dose adjusted in the PH

Answer 3

10 mg/kg

Question 4

INH needs adjustment for renal failure?

Answer 4

No

Question 5

Duration of latent Tb

Answer 5

9 months

Question 6

Why is pyridoxine given with INH and how does it produce neuropathy

Answer 6

INH increases urinary excretion of Vit B6 -> lowers plasma concentration -> peripheral neuropathy

Question 7

Most common major toxic effect of INH

Answer 7

Hepatitis

Question 8

Drug interaction of INH

Answer 8

Inhibits cyp450 -> decrease metab of other drugs |> inc toxicity

Question 9

Rifampin MOA

Answer 9

Bactericidal
Same site of action with InH
Binds to B-subunit of bacterial dna-dep rna pol -> no rna synthesis

Question 10

Rifampin excretion

Answer 10

Thru liver, bile, feces

Question 11

Uses of rifampin

Answer 11

Eliminate meningococcal carriage

Prophylaxis for contacts of children with Hib

Question 12

AE of rifampin

Answer 12

Harmless red-orange of all body secretions

Question 13

Drug interaction of rifampin

Answer 13

Inducer of cyp450

Question 14

Ethambutol MOA

Answer 14

Bacteriostatic (only bacteriostatic across all anti TB meds)

Inhibits arabinosyl transferase (for cell wall synthesis)

Question 15

Dose adjustment needed in ethambutol?

Answer 15

Yes

Question 16

AE of ethambutol

Answer 16

Reversible retrobulbar (optic) neuritis -> loss of VA and red green colorblindness

Question 17

MOA of pyrazinamide

Answer 17

Site of action: intracell bacilli only

Acting on mycobac fatty acid synthase 1 gene (for mycolic acid synthesis)

Question 18

Active form of pyrazinamide

Answer 18

Pyrazinoic acid

Question 19

AE of pyrazinamide

Answer 19

Hepatotoxicity

Question 20

MOA of streptomycin

Answer 20

Bactericidal
Inhibits protein synthesis by binding to bacterial 30s
Site of action: extracell bacilli only

Question 21

No longer used as 1st line agent

Answer 21

Streptomycin

Question 22

MOA of Ethionamide

Answer 22

Blocks synthesis of mycolic acid

Used for patients who became okay after 3 months and then get sick again after a year

Question 23

2nd line therapy from Streptomyces capreolus

Answer 23

Capreomycin

Question 24

Tx of drug-resistant TB

Answer 24

Capreomycin

Question 25

Most serious side effect of cycloserine

Answer 25

Depression and psychotic reaction

CI: epileptic px

Question 26

Alternative to streptomycin, used in MDR TB

Answer 26

Amikacin

Question 27

Fluoroquinolones that is most active against M. Tuberculosis

Answer 27

Moxifloxacin

Question 28

Fluoroquinolones more active than ciprofloxacin against M. Tuberculosis

Answer 28

levofloxacin

Question 29

Fluoroquinolones more active against ATYPICAL TB

Answer 29

Ciproloxacin

Question 30

Given to HIV px receiving ART witj protease inhibitors and NNRTs

Answer 30

Rifabutin (less potent inducer than rifampin)

-butin -> bitin -> less potent

Question 31

MOA of aminosalicylic acid

Answer 31

Bacteriostatic

Folate synthesis inhibitor

Question 32

AEs of aminosalicylic acid

Answer 32

CRANKS

Crystalluria, Rashes, Anemia, Nausea, Kernicterus, SJS-TEN (same with Sulfonamides)

Question 33

MOA of Bedaquiline

Answer 33

Bactericidal (BedaKILLine)

Inhibits ATP synthase

Question 34

AE of Bedaquiline

Answer 34

Cardiotoxicity - prolonged QT interval (bedaQuiline)

Question 35

Drug for leprosy that inhibits folate synthesis

Answer 35

Dapsone

Question 36

Initial treatment for lepromatous leprosy

Answer 36

Rifampin + dapsone + clofazimine