Antimycobacterial drugs

Question 1

two main species of mycobacteria that have cell envelopes

Answer 1

myobacterium tuberculosis

myobacterium leprae

Question 2

two targets or antimycobacterial treatment regimens

Answer 2

early reactions of mycolic acid synthesis

synthesis of NAG-arabinogalactan

Question 3

why are mycobacterial are so well protected from antimycobacterial agents

Answer 3

cell envelope is thick, asymmetric, and highly imperable to both hydrophilic and hydrophobic substances
cell wall resists entry to many antibiotics and the organism grows very slowly

Question 4

five first-line agents used to treat TB

Answer 4

ethambutol
pyrazinamide
isoniazid
rifampin
streptomycin

Question 5

what is a patient started on a four drug regimen?

Answer 5

patients with active TB and w/o hx of prior therapy

local prevalance of isoniazid resistance is > 4%

Question 6

when is a patient started on a three drug regimen?

Answer 6

if isoniazid resistance is rare (three-drug regimen doesn’t include ethambutol)

Question 7

what is the MOA of ethambutol?

Answer 7

bacteriostatic
decreases arabinogalactan synthesis by inhibiting the arabinosyl transferase that adds arabinose units to the growing arabinogalactan chain

Question 8

target of isoniazid action

Answer 8

FAS2 complex

Question 9

why isoniazid has drug interactions and three drugs affected by this

Answer 9

inhibits or induces cytochrome P450 enzymes

interacts with rifampin, anti-seizure medications: carbamazepine and phenytoin, azoletype antifungals, and alcohol