Vanco PK Flashcards
what is the MoA of vanco?
binds to peptidoglycan on bacterial cell membrane and interferes with cell wall building/repair
what does vanco treat?
MRSA, MSSA, and coagulase-negative staph
Vanco should be discontinued after 72 hours if?
MRSA not found
what is the minimum inhibitory concentration for vanco?
1 mg/L or less
what’s the bioavailability of vanco when given IV/IM?
F=1
what’s the bioavailability of vanco given intraperitoneally?
F= 0.5-0.6
what’s the dose for vanco given intrathecal/intraventricular?
5-20mg q24h
does vanco cross placenta?
does it get into breast milk?
yes and yes
when do we draw a vanco peak concentration after administration? what about post-distribution?
after 4-5 alpha half-lives
draw 1 hour after a 1 hour infusion
what is vancos half-life?
time to steady-state?
8 hours
48 hours
what are our monitoring parameters for efficacy and toxicity for vanco?
efficacy:
vitals (temp)
WBCs
repeat culture and sensitivty (C&S)
toxicity:
kidney function
SCr
Urine I/O
hearing & balance
vanco trough
what is the target vanco AUC for MIC =1 mg/L?
400-600 mg/L*h
why do we prolong infusion time w/ vanco doses over 1000mg?
prevent vanco flushing syndrome
some morbidly obese pts require every __ hour dosing
8
which of the following is true regarding vancomycin and obesity?
A. VD is moderately increased
B. T1/2 decreases to about 6 hours
C. Clearance increases
D. The Dosing interval remains the same
C
for burn patients, may need every ______ hour vanco dosing
6-8
a central line vanco concentration should NOT be _________
> 10 mg/mL
a peripheral line vanco concentration should NOT be __________
> 5 mg/mL
when do we consider using a loading dose for vanco?
seriously ill pts:
Severe sepsis
meningitis
bacteremia
infective endocarditis
pneumonia
osteomyelitis
what is vanco loading dose?
25-30 mg/kg based on actual body weight (max 3g)
what is the cockcroft-gault equation?
CLCR= [(140-age) x IBW / 72 X SCr] x 0.85 (for females)
how do we calculate IBW?
Men: 50 kg + 2.3 * (inches over 5 ft)
Women: 45.4 kg + 2.3 * (inches over 5 ft)
how do we determine what weight to use to calculate creatinine clearance?
use total body weight if its less than IBW. if IBW is 120% or more over TBW, use ABW
how do we calculate ABW?
IBW + [0.4 (TBW-IBW)]
when do we use a minimum Scr =1?
for age 65 or more or malnourished pts with Scr less than 1
how do we initially dose vanco based on creatinine clearance?
> 80: 15 mg/kg q8-12h
50-80: 15 mg/kg q12h
30-50: 15 mg/kg q24h
<15: 15 mg/kg as one time dose
** not to exceed 2g
q8h recommended only in patients under 40 and CLCR over 80
all vanco troughs should be drawn __________ to next dose (within ______ minutes of next dose)
immediately prior, 30
vanco troughs should be obtained at steady-state before ___________ dose in patient with stable kidney function or before _________ dose in patients requiring >24 hour dosing such as CKD patients
4th or 5th
2nd or 3rd
volume of distribution for vanco is determined using the equation:
when do you use ABW?
0.7 or 0.8 L/kg * weight
if >120% IBW
mcg/ml = mg/L
what does t’ mean?
infusion time: t’=2 if vanco was infused over 2 hours
what does tau mean?
the dosing interval: q12h, q24h…
if you want to change the Cmax, you should?
if you want to change the Cmin, you should?
change the dose
change the dosing interval
is vanco concentration-dependent or time-dependent killing?
time-dependent
AUC divided by the MIC is the primary predictive pharmacodynamic parameter for _____
efficacy
T/F AUC is the measure of cumulative drug exposure
true
T/F AUC is the serum concentration-time curve over a dosing interval
true
vanco trough range should be?
10-20 mg/L
for calculating extrapolated Cmax, Tmax is the time between __ and the _______
T1, end of infusion
Ct = concentration at the start of infusion which is the same as?
trough (Cmin) at steady-state
back extrapolating to the end of the infusion will
a. overpredict AUC
b. underpredict AUC
c. predict AUC exactly
b
what is the AUC associated w/ AKI?
600-800 mg/L*h
what is the AUC associated w/ nephrotoxicity?
700-1300 mg/L*h
smaller volume of distribution = what to k and half-life?
faster elimination and shorter half-life
prior to systemic circulation, oral drugs metabolized by cyp are located in the:
a. small intestine
b. liver
c. small intestine and liver
d. small intestine, liver, kidney, and other minor organs
d
which dosage form(s) have a high first-pass effect?
a. IV/IM
b. SL
c. capsule/tablet
d. transmucosal
e. transdermal
f. suppository
g. inhalation
c
in general, if a drug has a high first-pass effect, then switching from IV to oral dose requires:
a. a smaller oral dose
b. a larger oral dose
c. the same dose
b
if a drug has a high first-pass effect, then switching from an oral dose to IV requires:
a. a smaller IV dose
b. a larger IV dose
c. the same dose
a
