Lecture 2/3 - Vancomycin & AG Dosing

Question 1

Vancomycin MOA

Answer 1

Inhibits peptidoglycan synthesis by binding to D-ala-D-ala terminus of pentapeptide, statically interfering in elongation of cell wall polymer

Question 2

PK/PD of Vanco

Answer 2

bactericidal
In vitro killing is time dependent
outcomes best predicted by AUC/MIC

Question 3

Vanco metabolism

Answer 3

mostly renal

Question 4

Major toxicity of vanco

Answer 4

renal toxicity = elevated troughts + concurrent use of other nephrotoxic drugs

vancomycin infusion reactions = pruritus, rash to face/neck/upper torso, associated w/ rapid IV infusion

Question 5

Vanco coverage

Answer 5

MRSA
MSSA

Step pyogenes, S. pneu, Enterococcus Faecalis

Question 6

2020 guidelines AUC/MIC ratio target

Answer 6

400 to 600

typical dose needed to achieve this is 15-20mg/kg

Question 7

What is Efficacy perimeter for vanco

Answer 7

AUC/MIC > 400

Question 8

Vanco AKI defined as…..

Answer 8

SCr > 0.5mg/dL or 50% inc from baselines in consecutive daily readings

Dec in calc creatine clearance of 50% from baseline on 2 consecutive days in absence of alternative explanation

Question 9

Incidence of Vanco AKI risk factors

Answer 9

most episodes w/ longer treatment course ( > 4+ days)
Troughs > 15-20mcg/ml inc risk
AUC > 600mg*h/L inc risk

Question 10

Stepwise approach to vanco dosing

Answer 10

Loading Dose
Maintenance Dose
Monitoring levels
Consider special populations

Question 11

Who gets Vanco loading dose

Answer 11

recommended for critically ill pts = have to meet all 3

1. In ICU
2. Meets 2 SIRS criteria ( HR > 90, RR > 20, Temp > 96.8, WBC > 12/>4)
3. proven or suspected severe MRSA infection (sepsis, meningitis, bacteremia, endocarditis, pneumonia)

Question 12

Loading dose dosage Vanco

Answer 12

Max dose of 3000mg

Dose is 25-30mg/kg X Actual body weight

** consider lower doses in pts with AKI = 20mg/kg***

Question 13

When to use ABW vs IBW for Creatine Clearance Calculation

Answer 13

ABW used if less than IBW

Question 14

When to use adjusted dosing weight for creatine clearance calc?

Answer 14

when ABW > 130% of IBW

Question 15

CM to IN conversion

Answer 15

CM / 2.54

Question 16

Max CrCl if < 60yr

Answer 16

130ml/min

Question 17

Max CrCl if 60-69

Answer 17

90 ml/min

Question 18

Max CrCl if 70-79

Answer 18

70ml/min

Question 19

Max CrCl if > 80

Answer 19

50 ml/min

Question 20

Volume of Distribution Coefficients

Answer 20

Normal = 0.65L/kg
Obese = 0.55 L/kg
Septic Shock/ICU/Trauma = 0.75L/kg

** if more than 1 category, average them **
always use Total body weight

Question 21

Infusion time for 250mg dosing interval

Answer 21

1g/hr

Question 22

Aminoglycoside MOA

Answer 22

actively transported across cytoplasmic membrane into interior of bacterial cell

binds to 30S/50S subunit leading to misreading of genetic code and inhibit protein synthesis

Question 23

Aminoglycoside PK/PD

Answer 23

Bactericidal
Conc dependent (Peak:MIC)

Question 24

Aminoglycoside Metabolism/Excretion

Answer 24

Renal Elim, adjust req