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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

A

rifampin

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
Q

mycobacterium tb is aerobic/non aerobic and motile/nonmotile

A

aerobic non motile bacillus

26
Q

the ____ line drugs for mycobacterial infection are all teratogenic

A

2nd line drugs: streptomycin, amikacin, levofloxacin, ethionamide

27
Q

what 1st line agents of mycobacterium tb are given as prodrugs?

A
  • isoniazid

- pyrazinamide

28
Q

leprosy is caused by __________ and most of the cases are seen in ______

A

mycobacterium lepra and Mycobacterium lepromatis

70% seen in India

29
Q

streptomycin’s MOA

A

it is an aminocglycoside so it irreversibly inhibits the 30S ribosome
AE: ototoxicity, nephrotoxicity

30
Q

the most hepatotoxic first line drug used to treat mycobacterial infections is ______

A

isoniazid

31
Q

what is the MOA of rifampin?

A
  • inhibits RNA synthesis by blocking transcription by binding to β subunit of bacterial DNA dependent RNA polymerase
32
Q

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?

A

don’t stop dapsone because the nodules are immunological in origin. So give immunosuppressant such as corticosteroids or thalidomide

33
Q

drugs given for latent tb:

A
  • isoniazid

- rifampin

34
Q

what are some AE’s of pyrazinamide?

A
  • non gouty polyarthralgia
  • acute gouty arthritis
  • hyperuricemia
  • hepatotoxicity, myalgia, Gi irritation, rash, photosensitivity
35
Q

a patient is infected with M. leprae. What drug is bactericidal to M. leprae and what are some unique AE’s of it?

A

Clofazimine; red brown discoloration of the skin

anti inflammatory property of the drug → NO erythema nodosum

36
Q

your patient is found to have point mutations in rpm gene which codes for ________; this causes resistance to what drug?

A

codes for the β subunit of RNA polymerase → ↓ affinity of bacterial DNA dependent RNA polymerase for the drug → resistance to RIFAMPIN

37
Q

what are some common AE’s of isoniazid

A
  • 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
Q

what chromosomal mutations are associated with resistance to isoniazid?

A
  • mutation/deletion of KatG
  • mutations of acyl carrier proteins
  • over expression of inhA
39
Q

can rifampin be used in pregnant patients?

A

yes

40
Q

MOA of isoniazid

A

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
Q

what is the most bactericidal drug for leprosy?

A

rifampin

42
Q

can you give isoniazid to pregnant patents?

A

yes, but give B6 prophylaxis to ↓ risk of hepatitis

43
Q

what are 3 recommended drugs for leprosy?

A
  • dapsone
  • clofazimine
  • rifampin (most bactericidal drug for leprosy)
44
Q

what are some clinical applications of rifampin?

A
  • 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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