Chapter 112: Medication Dosing During Renal Replacement Therapy

INTRODUCTION

The aim of drug dosing is to maintain pharmacokinetics (a similar peak, trough, or average steady-state drug concentration) to achieve a desired pharmacodynamic response without adverse side effects.¹ In critically ill patients receiving renal replacement therapy (RRT), however, determining appropriate drug dosing is challenging because pharmacodynamic target attainment is determined by a complex interplay between drug dosing, pharmacokinetic changes within the critically ill patient, and the type of RRT selected (Table 112–1).² A stepwise approach for patients with chronic kidney disease and acute kidney injury has been proposed (Table 112–2).³ For assessment of kidney function, estimation by equation is generally more accurate than measured creatinine clearance, given errors in urine collection.⁴ Therefore, the National Kidney Disease Education Program in the United States recommends estimation of the glomerular filtration rate from the Cockcroft and Gault equation for adults: urinary creatinine clearance = (140 – age [years]) × weight (kg) × 0.85 (for female)/serum creatinine (mg/dL) × 72 or the Schwartz equation for children.^5,6