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PT3 ID 1 (HIV) > Tuberculosis pharmacology/therapeutics > Flashcards

Tuberculosis pharmacology/therapeutics Flashcards

1
Q

how is tuberculosis spread

A

through the air in droplets

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2
Q

extrapulmonary tuberculosis

A
  • tuberculosis infection that spreads beyond the lungs

- makes up about 15% of cases

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3
Q

mycobacterium tuberculosis features

A
  • gm+
  • mycolic acids make up outer membrane
  • slow growing
  • resides in macrophages
  • rapidly develop resistance
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4
Q

what do drugs target in TB

A

cell wall/FAS

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5
Q

symptoms of active TB

A
  • productive prolonged cough
  • coughing up blood
  • chest pain
  • fever
  • night sweats
  • easily fatigued
  • unexplained weight loss
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6
Q

symptoms of latent TB

A
  • no obvious symptoms

- granulomatous lesions in lung

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7
Q

positive TST(PPD) for HIV infected/immunocompromised

A

> 5 mm

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8
Q

positive TST(PPD) for high risk or injection drug user

A

> 10 mm

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9
Q

positive TST(PPD) for person with no risk factors

A

> 15 mm

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10
Q

TB vaccine

A

BCG

lasts 10-20 years

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11
Q

drug susceptibility test

A

MODS assay using sputum samples grows faster than normal cultures

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12
Q

1st line regimen for active TB infection

A

2 months: rifampin, isoniazid, pyrazinamide, ethambutol

then 4 months of: rifampin, isoniazid

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13
Q

isoniazid moa

A

inhibits biosynthesis of mycolic acids by binding to NAD to prevent elongation

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14
Q

isoniazid ADME

A
  • rapidly absorbed
  • t1/2 depends on fast or slow acetylators (1-3 hours)
  • inhibits hepatic enzymes
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15
Q

isoniazid adverse effects

A
  • peripheral neuropathy due to interference with pyridoxine (B6) metabolism, can be averted by Vit B6 supplements
  • rarely hepatitis
  • inhibits hepatic enzymes
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16
Q

rifampin moa

A

binds to beta-subunit of bacterial DNA dependent RNA polymerase preventing synthesis

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17
Q

rifampin ADME

A
  • lipid-soluble
  • t1/2 of 2-3 hours
  • induces and inhibits 3A4
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18
Q

rifampin adverse effects

A
  • reddish coloration of urine, tears, saliva
  • flu like symptoms
  • thrombocytopenia
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19
Q

rifampin drug interactions

A
  • oral anticoagulants
  • oral contraceptives
  • methadone
  • will need dosage changes*
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20
Q

ethambutol moa

A

inhibits cell wall by preventing mycolic acids from attaching to arabinogalactan

21
Q

ethambutol ADME

A

t1/2 = 3-4

22
Q

ethambutol adverse effects

A

optic neuritis that can lead to blindness if drug isn’t stopped

23
Q

pyrazinamide moa

A

binds ribosomal protein

only in pH

24
Q

pyrazinamide ADME

A

half life of 10 hours

25
Q

pyrazinamide adverse effects

A
  • GI intolerance

- occasionally gout

26
Q

multidrug resistant TB treatment

A

at least 4 effective drugs for 18-24 months

27
Q

risk that a person will have active TB in life time

A

10%

28
Q

how does PPD test work

A

tuberculin is injected and if the body has been exposed to TB the T cells are sensitized and mount a response

29
Q

recent converter

A

based on reading 2 years ago:
for <35 PPD increases by more than 10 mm
for >35 PPD increases by >15 mm

30
Q

who is at greatest risk of converting latent TB to active

A
  • weak immune systems

- starting steroid use

31
Q

isoniazid prophylactic dose in none HIV

A

300 mg qd for 9 months

32
Q

isoniazid prophylactic dose in HIV patients

A

300 mg qd for at least 12 months

33
Q

rifampin prophylactc dose

A

600 mg qd for 4 months

34
Q

what needs to be added to regimen in isoniazid based regimens for those at risk for neuropathy

A

pyridoxine (B6) 25 mg qd

35
Q

workup for active TB

A
  • signs and symptoms
  • chest xray
  • 3 morning sputum samples
  • PPD
36
Q

stain to see mycobacteria

A

acid fast bacilli stain of sputum, not culture

37
Q

treatment regimen for active TB initial phase

A

always 4 drugs for 8 weeks with pyridoxine

38
Q

if after initial treatment phase cavitation OR AFB positive

A

begin continuation phase as isoniazid and rifampin for 4 months

39
Q

if after initial treatment phase cavitation AND culture positive

A

isoniazid and rifampin for 7 months

40
Q

overall active TB treatment timing

A

-initial phase 2 months
-continuation phase 4-7 months
total = 6-9 months

41
Q

those at highest risk for neuropathy when taking isoniazid

A 
DM
alcoholics
malnourished
HIV
pregnancy
seizures
42
Q

isoniazid INH

A
  • inhibit hepatic enzyme
  • neuropathy
  • hepatitis
43
Q

drug that can cause thrombocytopenia

A

rifampin

44
Q

what to do if hepatitis occurs

A
  • stop isoniazid, rifampin, pyrazinamide
  • regimen with ethambutol and other abx
  • restart 1st lines when AST <2x upper limit of normal
45
Q

2nd line agents

A 
kanamycin
viomycin
capreomycin
amikacin
streptomycin
levofloxacin
cycloserine
ethionamide
46
Q

former 1st line agent that is now 2nd line

A

streptomycin due to ototoxicity

47
Q

what to do if resistant bugs are resistant to a drug

A

replace with at least 2 drugs it is susceptible to

48
Q

how to deal with GI distress

A
  • take with food or change dosing hour

- DO NOT split dosing (cutting tablets)

PT3 ID 1 (HIV) (5 decks)

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