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32 Cards in this Set
- Front
- Back
Vancomycin trough
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5-10
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ABW
If the actual body weight is greater than 25% of the calculated IBW, calculate the adjusted body weight |
IBW + 0.4(Total body weight - IBW)
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When is it most appropriate to check drug plasma concentrations
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steady state
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How many half-lives does it take for a drug to be almost completely eliminated
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4-5.
equivalent to 6.25%-3.125% of drug remaining in the body. After 7 half lives <1% |
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What determines half-life
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clearance (Cl) and volume of distribution (Vd)
half-life = 0.693Vd / Cl |
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What determines elimination constant
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Cl and Vd
ke = Cltb / Vd |
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What SrCr values give a better estimate of renal function for elderly with low SrCr (<0.8mL/ming)?
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1mg/dL
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When is a trough taken?
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30 mins before next dose
Ideally this trough would be equal to Cpmin. If trough is drawn earlier than right before the next dose: Cpmin = observed Cp trough x e^(Ke*time) |
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When is a peak taken?
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30 mins after a 30-min infusion
Cpmax = measured Cp peak / e^(Ke*time) where time is the difference between the time of the end of infusion and the time of the measured Cp |
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Antibaterial activity of aminoglycosides: time or concentration dependent killing?
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concentration.
Optimal batericidal activity is achieved when peak concentration is about 10 times MIC Higher peak = better clinical outcome |
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PAE
- varies with organism and concentration - greater for gram neg. than gram pos. - increases with increasing aminoglycoside peak concentrations |
prominent postantibiotic effect
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gram positive
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serious infections e.g. endocarditis, sepsis
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population Vd and t1/2 for gentamycin and tobramycin
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Vd ~ 0.3L/kg (will be higher in pregnant, critically ill, ascites, CHF pts)
t1/2 ~ 2h |
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When is it beneficial to give LDEI
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less toxic, less monitoring, less costly. also easier to convert to home IV therapy
Large dose extended interval dosing allows kidneys to recover from nephrotoxic effects of AGs. Efficacy will not be compromised because of PAE. |
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Who is eligible for LDEI
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good renal function.
AVOID in pts with altered Vd, pregnant, critically ill, quadriplegics, ascites, CF, renal dysfunction CrCl <20mL/min, ESRD on hemodialysis or CAPD |
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Gentamycin/tobramycin Cp max and Cp min
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Cpmax = 15-20mcg/mL
Cp min <1mcg/mL or undetectable gentamicin MIC for pseudomonas aeruginosa is usually ~ 2mcg/mL, so desired Cmax is about 20mcg/mL. |
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Gentamycin/tobramycin drug-free period
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Optimally, 4 hours <0.5mcg/mL
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gentamicin/tobramycin empiric dosing
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gram neg: 5-7mg/kg/dose
gram pos: 3mg/kg/dose CrCl>60: Q24h >40: Q36h >20: Q48h |
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gentamicin/tobramycin monitoring
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Peak: random level 8-12 after 1st dose. 30 mins after second 30-minute infusion
Trough: 24h after 1st dose. continue regimen if <1mcg/mL |
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gentamicin/tobramycin target concentrations (with conventional dosing)
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Cpmax
synergy for gram pos: 3-4mcg/mL gram neg: 6-8mcg/mL (UTIs, bacterimia, pneumonia, sepsis) cystic fibrosis: 8-12mcg/mL Cpmin: <1-2mcg/mL |
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gentamicin/tobramycin empiric therapy
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Loading IV bolus dose: 2mg/kg i.e. desired plasma conc x Vd
Interval: (lnCpmax - lnCpmin) / ke...which is 0.0293*CrCl+0.01...+ infusion time in hr. Interval is usually ~ 3 t1/2s Maintainence: they are A-holes if they want you to calculate this without a log-function calculator. So the answer is A. |
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gentamicin/tobramycin monitoring
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WBC
temperature cultures infection s&S peaks especially if aggressive targets are used (peak of 8mcg/mL or trough of 2mcg/mL) BUN/SCr/UO ototoxicity troughs |
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gentamicin/tobramycin steady state
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4 SrCrs is about one half-life. So steady state is about 4*SrCr *4 = 16*SrCr.
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amiodarone
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blue syndrome
3A4 inhibitors check thyroid function |
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1c
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blocks Na
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3
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can use in CVdz
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sotalide
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only for maintainence
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dofetalide
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quickest onset, dose based on CrCl and QTc
blocks K+ from reentering AVOID using with HCTZ |
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1st afib <48h
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rhythm
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ibut
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IV, most stay in hosp>3d for obs
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2a
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amiodarone
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QTc prolongating drugs
(>440 msec) |
quinidine (also causes D)
procainamide (also causes lupu) |