Tuberculosis Meds Flashcards
1
Q
Mandel-Mantoux Test
A
- TST aka PPD
- must be read within 48-72 hours
- immunosuppressed pts (HIV, transplant, prior tb)
- 5+mm = positive
- Immunocompetent pts but high risk
- 10+ mm = positive
- Anybody with no known risk
- 15+ mm = positive
2
Q
2-step TST testing
A
- if negative rxn = retest 1-3 weeks later
- if positive = rxn = boosted due to TB infx that happened a while ago, may or may not treat LTBI
- if negative = person most likely does NOT have TB infx
- if positive rxn = f/u for + TST and evaluate for LTBI tx
3
Q
IGRAs
A
interferon-gamma release assays → infected WBCs produce interferon-gamma (IFN-g)
- used to detect TB via blood test
- Quantiferon-TB Gold plus
- measure IFN-g level in blood
- T-spot
- measure of # of IFN-g producing cells (spots) – WBC
- Advantages:
- unaffected by BCG vaccine or other non-TB mycobacteria
- results <24 hours vs 3 days with TST (PPD)
- Disadvantages:
- samples need to be processed in 8-30hours when WBCs are still viable
- sensitivity may lower in immunocompromised
- limited data for kids <5 yo; recently exposed to TB; and healthcare workers
- more expensive
4
Q
Sputum Test and TB
A
AM sputum collections x 3 days
- can be induced by using aerosolized hypertonic saline
- sputum is then smeared on a slide and stained with an “acid-fast” procedure
- results available in a few hours
- postive result? → presumptive positive diagnosis of tb
5
Q
LTBI
A
Latent TB Infection
- TB is in the body but is encapsulated by immune system cells
- no s/sxs of TB
- Results:
- TST/IGRA results = +
- CXR = -
- smear and cx = -
- cannot spread to others
-
High Priority for tx:
- HIV infected pts
- fibrotic changes on CXR
- organ transplant recipients
- immunosuppressed pts
- >15mg/day of prednisone for 1+ months
- taking TNF-alpha antagonists
- etanercept (Enbrel)
- infliximab (Remicade)
- adalimumab (Humira)
- IV drug users
- immigrants <5 yrs
6
Q
Mycobacterial Cell Wall
A
Two important layers:
- mycolic acid layer more superficial
- arabinogalactan layer is deep to the other layer
7
Q
Which TB drugs inhibit cell-wall synthesis
A
IPE:
Isoniazid
Pyrazinamide
Ethambutol
and TCA1 (and inhibits cofactor biosynthesis)
8
Q
Which TB drug inhibits RNA synthesis
A
Rifampin
9
Q
Which TB drug inhibits ATP synthase
A
bedaquiline (Sirturo)
10
Q
Rifamycins
A
-
Rifampin (Rifadin)
- SEs: nausea, anorexia
- hepatotoxicity
- discoloration of body fluids
- DDI: 1A2, 2C9, 3A4 inducer
- SEs: nausea, anorexia
-
Rifabutin (Mycobutin)
- SEs:
- neutropenia, leukopenia, thrombocytopenia
- uveitis
- hepatotoxicity
- flu-like sxs
- discoloration of body fluids
- DDI: less than rifampin, weak inducer
- SEs:
-
Rifapentine (Priftin)
- SEs:
- similar to rifampin
- DDI:
- similar to rifampin
- SEs:
11
Q
Isoniazid
A
- prodrug
- SEs:
- hepatitis → elevation of LFTs (liver function tests)
- neuropathy→ Should give with Vitamin B6
- lupus-like syndrome → swollen, painful joins, fever, butterfly-shaped rashes (Milar rash)
- monitor LFTs monthly if pt has liver dz
- DDI:
- 2C19 and 3A4 inhibitor (weak) → increase levels of AED and warfarin
12
Q
Pyrazinamide
A
- MOA unclear but more active in acidic pH
- active against dormant or semi-dormant TB in cytoplasm
- prodrug→ pyrazinoic acid (POA)
- SEs:
- hepatotoxicity
- N/V
- hyperuricemia → gout attack
- rashes
- Monitoring:
- LFTs with liver disease
- uric acid levels (a good marker for compliance)→ gout problems
- DDI: allopurinol, febuxostat, probenicid (PZA antagonizes effects)
13
Q
Ethambutol
A
- SEs:
- optic neuritis → irreversible blindness
- neuropathy, headache, dizziness, confusion
- rashes, hepatotoxicity
- Monitoring:
-
baseline visual acuity and color
- espec in pts with renal insufficiency or therapy longer than 2 months
-
baseline visual acuity and color
- DDI:
-
antacids reduce absorption
- should separate by 4 hours
-
antacids reduce absorption
14
Q
Treatment Interruptions for TB Intensive Phase
A
- Initial phase:
- 2 months with 4 drugs
- <14 days: continue tx, if not totally completed in 3 months, restart from beginning
- ≥ 14 days: restart from beginning
15
Q
Treatment Interruptions for TB in Continuation Phase
A
- Continuation phase:
- ~4.5 months total of 2 drugs
-
<80% of planned doses completed
- < 3 months → continue treatment, if not completed in 6 months, start from beginning
- ≥ 3 months → restart 4-drug regimen from the beginning
- ≥ 80% → additional tx may not be necessary