Pharm 2 Flashcards
what is the goal of tb treatment
prevent tb spread
know where tb has spread
return patient to well being and normal weight
what is used for treatment of latent tb
INH for 9 mths daily (300mg)
rifampin or rifabutin for 4 mths daily
INH and rifapentine for weekly for 12 weeks DOT
What is used for active tb treatment
3-4 first line (isoniazid, ethambutol, pyrazinamide and rifampin ) for 6 mths
what is the shortest duration for active tb treatment and when
4mth in culture negative 2
how much can tb treatment last in MDR-TB
2 years
when can we use second line drugs
if patients cannot tolerate 1st line and resistant tb
when can you use monotherapy and when multiple drug therapy
monotherapy for latent tb
multiple for active ( monotherapy doesnt work)
Mycobacterium tb has small number of naturally resistant mo but when do they increase in number
inadequate treatment with monotherapy causing resistant tb
active disease require treatment with multi drug therapy
true
are patients in latent tb infectious
no not infectious
no isolate can be taken from latent tb infections so we cant perform susceptibility test so treatment based on most likely source of infection
true
what can replace rifampin
rifabutin or rifapentine
clinical improvement can occur in first weeks of treatment but you should continue
eradicate persistent organism
prevent relapse
course of tb treatment ( 2 phases)
intensive phase ( all 4 for 2 mths) continuation phase (rifampin and INH for 4 mths)
what are second line regimens for MDR TB
injectable aminoglycoside (amikacin, streptomycin, kanamycin and capreomycin) florouquinolones , one of active 1st line and cycloserine, ethionamide and p-aminosalicylic acid
treatment for XDR-TB
linezolid or clofazimine
what is XDR-TB
resistant to two imp 1st line
resist floroquinolone
resist one of injectable
DOTS plus pilot program by who and for what
WHO representative
strengthen DOT program
what is special about doses in pediatric
doses of INH an rifampin on mg /kg basis is higher than adults ( dosing is higher but not dose)
can you use it in pregnancy
yes
extended therapy for 9mth is pediatric is recommended by some protocols
true
what drugs are prodrugs
isoniazid and pyrazinamide
how is isoniazid converted to active form and what is its MOA
by mycobacterial catalase peroxidase
target enzyme for mycolic acid synthesis disrupting cell wall
what is the resistance in isoniazid and rifampin and pyrazinamide
isoniazid chromosome mutation
rifampin mutation in affinity of DNA dependent RNA pol
pyrazinamide lack pyrazinamidase enzyme
cross resistance can occur with what two drugs
isoniazid and ethionamide
what drug absorption is impaired when taken with food (high fat)
isoniazid
drug conc in CSF in INH and rifampin and ethambutol
INH have same conc in drug and plasma
rifampin has 10-20% of blood conc in CSF
ethambutol CSF conc is minimal
what happens to isoniazid in liver
N acetylation and hydrolysis giving rise to inactive product
rapid acetylator of INH and slow acetylator of INH difference
rapid has short t1/2 almost 1 hour
slow has longer t1/2 almost 3 hours
excretion of INH through what
filtration and secretion
slow acetylators excrete what
parent compound and metabolite
side effects of INH
hepatitis (increased risk in chronic alcoholics , age more than 35 and those who take also rifampin)
peripheral neuropathy
peripheral neuropathy of INH due to what and how treated
pyrodoxine def
25-50mg per day should be given
rifampin, rifabutin and rifapentine from what family
rifamycin
rifampin should never be given as single agent in active tb
true
rifampin, ethambutol and streptomycin penetrate BBB in what case
inflamed meninges
what drug induces CYP450 and autoinduction
rifampin
shortened half life over the 1st 1-2 weeks of taking rifampin
true
what should be done to solve cyp450 induction
higher the dose of co administered drugs
switch to drugs less affected by rifampin
replace rifampin with rifabutin
what are the color of fluids due rifampin
orange red
when to use rifabutin
TB patients who are also HIV positive that are recieving PI and NNRTI
Rifabutin is 40% less inducer to CYP450 compared to rifampin
true
which rifamycin has the greatest activity and longer half life
rifapentine
when is rifapentine used
in HIV negative patients with pulmonary TB
How is pyrazinamide converted to active and what is the active called
pyrazinamidase
pyrazinoic acid
pyrazinamid is taken orally
true
MOA of ethambutol
bacteriostatic
main S/E of ethambutol
optic neuritis
diminished visual acuity and loss of ability to differentiate between red and green
visual acuity and color discrimination should be tested before starting treatment and periodically after
true
S/E of pyrazinamide
hyperurecemia (gout) and hepatitis
S/E of flroquinolone
achilles tendon rupture ( tendonitis)
C/I in patients less than 8 and in pregnant
ethionate and p-aminosalicylic acid S/E
Hypothyroidism and hepatotoxicity
macrolide S/E
tinnitus
aminoglycoside S/E
ototoxic and nephrotoxic
