Antimycobacterials

Question 1

Mycobacteral infections

Answer 1

Difficulte to treat
Hide in macrophages, cavitary lesions, many drug resistance (high prob that resistant to one drug so have to use multiple at the same time)

Question 2

First line TB Tx

Answer 2

Isoniazid + Rifampin for 6-9 months

Pyrazinamide & Ethambutol/Streptomysin for first 2 months

Question 3

Rifampin

Answer 3

Inhibits RNA polymerase initiation
Use: TB & many other bacteria
Bactericidal
Oral & bile excretion
Synergistic w/ING & streptomycin

Question 4

Isoniazid

Answer 4

Related to nicotine
Inhibits mycolic acid synthesis (binds adenine nucleotide 
Bacteriocidal if growing 
Oral & Renal excretion
Resistance from INH2 mut

Question 5

Isoniazid SE

Answer 5

Peripheral & optic neuritis,
Hepatoxicity (more risk in Asians because fast acetylators = more acetylhydrazine)
Rash, fever
Pregnancy C but benefits may outweigh

Question 6

Rifampin SE

Answer 6

Turns body fluids red (tears, etc)
Rash, fever, n/v
DDIs w/p450 (HIV, steroids, OC)
Preg C

Question 7

Ethambutol

Answer 7

Tuberculostatic/cidal
Inhibits cell wall synth through arabinosyltransferase inhib embB
Oral & renal excret

Question 8

Ethambutol SE

Answer 8

GI
Optic neuritis (color/peripheral) irrev
Preg C

Question 9

Pyrazinamide

Answer 9

Hydrolyzed to pyrazinoic acid
Bactericidal
Unknown mech
Active at low pH

Question 10

Pyrazinamide SE

Answer 10

Hepatic
Gout
GI
Arthralgias
Preg C

Question 11

Leprosy Tx

Answer 11

Dapsone
+Rifampin
+Clofazimine
Sometimes years of therapy

Question 12

Mycobacterium avium complex Tx

Answer 12

Macrolides
+Ethambutol
+/-Rifabutin

Question 13

INH resistance

Answer 13

katG mutation