Antituberculotics Flashcards
what are the first line antiTB drugs?
isoniazid rifampin pyrazinamide ethambutol streptomycin rifabutin
What is the first line combination treatment for active TB?
INH, Rif, EMB, PZA
What is the course of treatment for latent TB?
either…
INH + RPT q once weekly for 3 months
OR
RIF q daily for 4 months
OR
INH q daily or twice weekly for 6-9 months
what does INH inhibit?
mycolic acid synthesis
when INH is given alone, is it static or cidal?
static
combination with what drug makes INH cidal?
rifampin
When considering prophylactic therapy, INH associated hepatitis should be considered especially in patients above what age?
> 35
Describe the metabolism of INH
metabolism in the liver via acetylation
What are five major toxicities of INH?
hepatitis, peripheral neuritis, hemolysis, lupus like syndrome, CNS stimulation
who should you consider for INH induced hepatitis?
older persons, fast acetylators
who should you consider for peripheral neuritis when administering INH?
slow acetylators
who should you consider for risk of hemolysis when adminstering INH?
G6PD deficiency
what is the mechanism of action for rifampin?
inhibition of DNA dependent RNA polymerase
what confers resistance to rifampin?
rpoB mutation
which tuberculo-static drug comes closest to the activity of INH?
rifampin
Why is rifampin not recommended for HIV treated individuals?
CYP450 induction can cause drug interactions w/ HAART
A patient takes oral contraceptives and rifampin. what should you caution them on?
rifampin decreases birth control effectiveness via CYP450 induction
how does ethambutol work?
inhibition of arabinosyl transferases
is ethambutol cidal or static?
static
is ethambutol given for prophylaxis of TB?
no
Where is ethambutol well absorbed?
most tissues, and into the CNS
do you need to adjust the dose of ethambutol in renal failure?
yes
Describe the major adverse effect of ethambutol…
decreased visual acuity, loss of red/green perception
reversible upon discontinuation
is ethambutol recommended for children under 13?
no due to adverse effect on vision. This is NOT a contraindication. monitor closely
at what pH is pyrazinamide active?
acidic pH
do you change dosage if your patient is showing signs of fast or slow acetylation of INH?
No
what do you give in addition to INH to prevent peripheral neuritis?
Pyridoxine
does rifampin cause hepatotoxicity?
no
does pyrazinamide reach the meninges?
yes!
If a patient w/ active TB is experiencing hepatic dysfunction, which drug do you take them off of first? INH or PZA?
PZA and replace with a second line drug
When is streptomycin used for TB?
as a second line in MDR, XDR
What differentiates rifabutin from rifampin?
less potent induction of P450s
when do you use rifabutin instead of rifampin?
in HIV-TB co-infected individuals
when do you use rifapentine?
preferred regimine + INH for latent TB
describe the drug interactions with rifapentine…
moderate P450 induction
what 2 bacteria make up the mycobacterium avium complex?
m. avium and m. intracellulare
how is MAC treated and for how long?
12 months,
clarithromycin/azithro + ethambutol + rifabutin/rifampin/cipro
why does m. leprae require multidrug therapy?
monotherapy will always result in resistance to that drug
what constitutes PB leprosy?
1-5 patches
how do you treat PB leprosy?
rifampin + dapsone for 6 mo
what constitutes MB leprosy?
> 5 patches
how do you treat MB leprosy?
rifampin + dapsone for 6-12 months
what is the mechanism of dapsone?
PABA antagonist, similar to sulfa
describe the rate of excretion of dapsone…
slow
what is the most serious side effect of dapsone?
serious nasal obstruction interfering with patient compliance
Dapsone? DatNoseDoe!
why is thalidominde used in treatment of leprosy?
it is the DOC for moderate to severe erythema nodosum leprosum
