Antimycobacterial agents

Question 1

non-tuberculous mycpbacteria

Answer 1

M. avium

M. intracellulare

Question 2

primary drugs used in TB

Answer 2

Isoniazid
Rifampicin
Pyrazinamide
Ethambutol

Question 3

most active TB drugs

Answer 3

Isoniazid and rifampicin

Question 4

Isoniazid and rifampicin

Initial intensive phase of tx is recommended for the first __ months

Answer 4

2

Question 5

how many active agents should be used to treat active TB to prevent emergence of resistance during therapy

Answer 5

at least 2

Question 6

primary tx tb

Answer 6

2 months of HRZE and

4 months of HR

Question 7

maximum dose of H

Answer 7

300mg/day

Question 8

Max dose of rifampicin

Answer 8

600mg/day

Question 9

category 1

for pulmonary and extrapulmonary meninges, bones or joints

Answer 9

2 HRZE

4 HR

Question 10

Category 1a

for extrapulmonary TB of meninges, bones, and joints

Answer 10

2 HRZE
10 HR

max 1 yr

Question 11

Category 2

for retx of confirmed rifampicin-sensitive pulmonary and extra-PTB except meninges, bones or joints

Answer 11

2HRZES
1HRE
5HRE

Question 12

for retreatment of confirmed rifampicin-sensitive extra-PTB of meninges, bones, or joints

Answer 12

2HRZES
1HRE
9HRE

Question 13

most active drug for the tx of TB caused by susceptible strains

Answer 13

isoniazid

sim struc: pyridoxine

Question 14

isoniazid inhibits most tubercle bacilli at a concentration of __

Answer 14

0.2 mcg/mL

Question 15

isoniazid MOA

Answer 15

inh synth of mycolic acids

bactericidal

Question 16

Isoniazid resistance

Answer 16

overexpression of inhA
mutation or deletion of the katG gene
overexpression of ahpC
mutations in kasA

Question 17

isoniazid is readily absorbed from GIT optimally on an _____

Answer 17

empty stomach

Question 18

rapid acetylators (inh)

Answer 18

<1-hour half life

Question 19

slow acetylators (INH)

Answer 19

around 3 hours

Question 20

sleeping tb

Answer 20

latent tb

diagnosis: PPD or interferon gamma release assay or positive IgA test for TB.

Question 21

dosage for latent TB

Answer 21

INH 300mg/day or 900mg twice weekly (9 months; ph: 6 months)

Question 22

isoniazid immunologic rxn

Answer 22

fever and skin rashes

SLE

Question 23

Direct toxicity

Answer 23

hepatitis (most common major toxic effect)

Question 24

10-20% of patients given doses are greater than 5mg/kg/d, but it is frequently seen with the standard 300mg adult dose (INH)

Answer 24

peripheral neuropathy

Question 25

neuropathy is reversed by

Answer 25

pyridoxine b6 10mg/d (25-50mg/day)

Question 26

antibiotic produced by Amycolaptosis rifamycinica

Answer 26

Rifampin (S. mediterranei)

Question 27

rifampicin is active in vitro against

Answer 27

gram + some gram - (neisseria and haemophilus) mycobacteria Chlamydiae

Question 28

Rifampin MOA

Answer 28

binds to the B subunit of bacterial DNA-dependent RNA polymerase and thereby inhibits RNA synthesis

Question 29

Rifampin resistance

Answer 29

mutations in rpoB

Question 30

rifampin is excreted mainly through the____

Answer 30

liver and bile

Question 31

Latent tb | -single agent alternative to isoniazid dosage is ______

Answer 31

600mg/day for 4 months

Question 32

dosage meningococcal carriage elimination

Answer 32

600mg BID x 2 days

Question 33

H. influenzae type b disease prophylaxis

Answer 33

600mg OD x 4 days

Question 34

AE of rifampin

Answer 34

harmless orange color urine, sweat and tears Rashes, thrombocytopenia, and nephritis cholestatic jaundice and occasionally hepatitis

Question 35

synthetic water-soluble, heat-stable compound

Answer 35

Ethambutol

Question 36

the dextro isomer of the structure is dispensed as

Answer 36

dihydrochloride salt

Question 37

ethambutol MOA

Answer 37

inh mycobacterial arabinosyl transferases, which are encoded by the embCAB operon

Question 38

ethambutol resistance

Answer 38

Due to the mutations resulting in overexpression of emb gene products or within the embB structural gene

Question 39

accumulates in renal failure, the dose should be reduced to 3x weekly if creatinine clearance is less than 30mL/min

Answer 39

Ethambutol

Question 40

most common serious AE of ethambutol

Answer 40

retrobulbar neuritis (x visual acuity and red-green color blindness)

Question 41

relative of nicotinamide, and it is only used for treatment of tuberculosis

Answer 41

Pyrazinamide

Question 42

active form of pyrazinamide

Answer 42

Pyrazinoic acid

Question 43

pyrazinamide resistance

Answer 43

due to impaired uptake of pyrazinamide or mutations in pncA that impair conversion of PZA to its active form

Question 44

important front-line drug used in conjunction with isoniazid and rifampin in short-course regimens as a "sterilizing agent" active against residual intracellular organisms that may cause relapse

Answer 44

Pyrazinamide

Question 45

AE pyrazinamide

Answer 45

``` Hepatotoxicity Hyperuricemia Nausea Vomiting Drug fever Photosensitivity ```

Question 46

2nd line TB

Answer 46

streptomycin

Question 47

streptomycin resistance

Answer 47

point mutation rpsL (s12) gene or rrs gene (16s)

Question 48

streptomycin AE

Answer 48

Ototoxic | Nephrotoxicity

Question 49

MAC

Answer 49

M avium | M intracellulare

Question 50

recommended for initial therapy of lepromatous leprosy

Answer 50

dapsone

Question 51

dapsone may also be used to prevent and treat ______ in aids patients

Answer 51

Pneumocystis jirovecii pneumonia

Question 52

AE dapsone

Answer 52

Hemolysis Methemoglobinemia Erythema nodosum leprosum

Question 53

highly effective drug in leprosy

Answer 53

rifampin 600mg daily

Question 54

phenazine dye used in the tx of multibacillary leprosy

Answer 54

clofazimine

Question 55

common dosage of clofamizine

Answer 55

100-200mg/day orally

Question 56

most prominent adverse effect of clofamizine is

Answer 56

discoloration of the skin and conjunctivae