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PCM Exam 3 > Antimycobacterial Drugs > Flashcards

Antimycobacterial Drugs Flashcards

1
Q

a patient taking a drug for tb compulsion fo ↓ visibility and slight color blindness. what is the most likely drug and its MOA?

A

drug: ethambutol
MOA: ↓ carbohydrate polymerization of the cell wall by inhibiting arabinosyl transferase

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2
Q

what is used in the initial phase in the empiric treatment of tb?

A

isoniazid, rifampin, pyrazinamide, ethambutol for 8 weeks

“4 for 2, 2 for 4”

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3
Q

rifampin is a strong CYP 450 ______

A

inducer

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4
Q

_______ is a drug that is a analog of vitamin B6 (pyridoxine) and is given as a active/prodrug

A

isoniazid; given as a prodrug

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5
Q

if the patient has more severe leprosy ( more than 5 skin lesions), what is the recommended treatment?

A
  • treatment for mild leprosy + clofazimine
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6
Q

what are some second line drugs for tuberculosis

A
  • streptomycin
  • ethionamide
  • levofloxacin
  • amikacin
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7
Q

what are the first line drugs for tuberculosis?

A
  • isoniazid
  • rifampin
  • rifabutin (1st line in HIV positive patients)
  • ethambutol
  • pyrazinamide

RIPE

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8
Q

dapsone is structurally related to _____ and thus its MOA is : ________. it is bacterio______

A

sulfonamides → inhibits folate synthesis by inhibiting dihydropteroate synthetase and patients can present with hemolysis

bacteriostatic

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9
Q

dapsone is a CYP 450_____

A

inhibitor (like sulfonamides)

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10
Q

harmless orange/red colored bodily fluids is an AE of ______

A

rifampin

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11
Q

if the patient has mild leprosy (1-5 skin lesion) what is the recommended treatment?

A
  • rifampin + dapsone
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12
Q

other than leprosy, what can dapsone be used for?

A

treating P. jirovecii infection in HIV patients

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13
Q

hyperuricemia that can precipitate gout is an AE of ______

A

pyrazinamide

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14
Q

ethionamide is similar in structure to ______. what are some adverse effects of ethionamide?

A

isoniazid but not cross resistance

AE’s: endocrine effects such as gynecomastia, hypothyroidism, hypogonadism

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15
Q

what are some mechanisms that confers resistance to pyrazinamide

A
  • lacks the enzyme pyrazinamidase which is what converts the pro drug form to the active form
  • ↑ efflux of the drug
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16
Q

_____ is the preferred drug for use in HIV patients with tuberculosis. Why?

A

Rifabutin because it has less induction of CYP 450

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17
Q

when would you administer clofazimine?

A

it is added to the recommended to the treatment for severe leprosy (mild treatment (dapsone + rifampin) + clofazimine) )

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18
Q

________ is used for prophylaxis for kids with type B H influenza infection

19
Q

isoniazid is used as mono therapy for ______

A

latent tb; for active tb, give isoniazid as part of combination therapy to prevent resistance

20
Q

this first line antimycobacterial drug works by inhibiting the arbinosyltransferase leading to ↓ carbohydrate polymerization of the cell wall. What is a common AE of this drug?

A

drug: ethambutol
- dose dependent visual disturbances such as red/green color blindness

optic neuropathy
“EYE-thambutol”

21
Q

_______ is bactericidal for both intracellular and extracellular mycobacteria:

A

rifampin; can be used to treat m. tuberculosis and M. kansasii

22
Q

the teratogenic effect of _____ (drug) is that it can cause arthropathy (disease of a joint)

A

levofloxacin (inhibits DNA gyrase enzyme)

23
Q

what drugs are used in the continuation phase for empiric treatment of tb?

A

isoniazid and rifampin for 18 weeks

“4 for 2, 2 for 4”

24
Q

non gouty polyarthralgia is an AE of what drug?

A

pyrazinamide

25
mycobacterium tb is aerobic/non aerobic and motile/nonmotile
aerobic non motile bacillus
26
the ____ line drugs for mycobacterial infection are all teratogenic
2nd line drugs: streptomycin, amikacin, levofloxacin, ethionamide
27
what 1st line agents of mycobacterium tb are given as prodrugs?
- isoniazid | - pyrazinamide
28
leprosy is caused by __________ and most of the cases are seen in ______
mycobacterium lepra and Mycobacterium lepromatis 70% seen in India
29
streptomycin's MOA
it is an aminocglycoside so it irreversibly inhibits the 30S ribosome AE: ototoxicity, nephrotoxicity
30
the most hepatotoxic first line drug used to treat mycobacterial infections is ______
isoniazid
31
what is the MOA of rifampin?
- inhibits RNA synthesis by blocking transcription by binding to β subunit of bacterial DNA dependent RNA polymerase
32
a patient with leprosy is taking dapsone. They come back to you complaining of painful nodules on their skin (erythema nodosum leprosum). What would you do?
don't stop dapsone because the nodules are immunological in origin. So give immunosuppressant such as corticosteroids or thalidomide
33
drugs given for latent tb:
- isoniazid | - rifampin
34
what are some AE's of pyrazinamide?
- non gouty polyarthralgia - acute gouty arthritis - hyperuricemia - hepatotoxicity, myalgia, Gi irritation, rash, photosensitivity
35
a patient is infected with M. leprae. What drug is bactericidal to M. leprae and what are some unique AE's of it?
Clofazimine; red brown discoloration of the skin anti inflammatory property of the drug → NO erythema nodosum
36
your patient is found to have point mutations in rpm gene which codes for ________; this causes resistance to what drug?
codes for the β subunit of RNA polymerase → ↓ affinity of bacterial DNA dependent RNA polymerase for the drug → resistance to RIFAMPIN
37
what are some common AE's of isoniazid
- peripheral neuropathy: due to isononized antagonizing B6 which s required to create neurotransmitters; correct with B6 supplementation - hepatotoxicity - CYP 450 INHIBITOR - lupus like syndrome INH: Injures Neurons and Hepatocytes
38
what chromosomal mutations are associated with resistance to isoniazid?
- mutation/deletion of KatG - mutations of acyl carrier proteins - over expression of inhA
39
can rifampin be used in pregnant patients?
yes
40
MOA of isoniazid
it is given as a pro drug that is activated by a mycobacterial catalase peroxidase (KatG) targets enzymes involved in mycolic acid synthesis: - enoyl acyl carrier protein reductase (InhA gene) - β ketoacyl ACP synthase (KasA gene)
41
what is the most bactericidal drug for leprosy?
rifampin
42
can you give isoniazid to pregnant patents?
yes, but give B6 prophylaxis to ↓ risk of hepatitis
43
what are 3 recommended drugs for leprosy?
- dapsone - clofazimine - rifampin (most bactericidal drug for leprosy)
44
what are some clinical applications of rifampin?
- active (isoniazid intolerant patients) and latent TB infections - leprosy - prophylaxis for individuals with meningitis - prophylaxis in kids with H influenza type B

PCM Exam 3 (32 decks)

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