PK Module 16: In-Class Activity

Front

Identify the vancomycin dosing weight to be used in the following scenario: LM, a 55-year-old man, 5' 10'' tall, weighing 70 kg (IBW = 73 kg). Options: Ideal Body Weight, Actual or Total Body Weight, Adjusted Body Weight.

Back

Actual or Total Body Weight

Answer explanation

Vancomycin is dosed using TBW

Tags

Pharmacokinetics

Front

Calculate the AUC₂₄ /MIC for a patient receiving a 1500 mg vancomycin daily dose with a Cl_vanc = 4.0 L/hr and determine if the dosing is adequate. (MIC to vancomycin = 1 mg/L).

Back

Dosing is not adequate. Dose needs to be increased.

Answer explanation

AUC_0-24 = Vancomycin Daily Dose/Vancomycin Clearance = 1500 mg / 4 L/hr = 375 mg*hr/L

This is < 400 mg*hr/L, so therapy is inadequate.

Front

What is the half-life of vancomycin (in hr) in this patient?

Back

5.8

Answer explanation

Ke = ln (C1/C2)/t2-t1

K = ln (44mg/L/16mg/L) / (12 - 3.5 hr) = 0.119 hr-1

t1/2 = 0.693/K = 0.693/0.119 = 5.8 hr

Front

Compute a new vancomycin dose in mg that would provide an AUC₂₄/MIC = 500 for a 56-year-old, 76-kg male with MRSA pneumonia and a current serum creatinine of 1.5 mg/dL. Current dose is 1000 mg every 24 hours with a steady-state trough concentration of 7 μg/mL and AUC₂₄/MIC = 265.

Back

1887

Answer explanation

Dose_new/AUC₂₄/MIC_new = Dose_old/AUC₂₄/MIC_old 

Dose_new = (1000/265) x 500 = 1887 mg/day