Drug Dosing in Renal Failure Flashcards
Volume of distribution
Reduction in tissue binding
Body composition altered
Protein bind (decreased binding of acidic drugs and altered basic drug binding)
Phenytoin Normal concentration
10-20 mcg/mL
90% is bound
Phenytoin + Renal insufficiency
Leads to low albumin and difference in bound to free ratio
Hypoalbuminemia + Phenytoin
PHT / ((0.2*albumin)+0.1)
Hypoalbuminemia + Phenytoin + Renal insufficiency
PHT / ((0.1*albumin)+0.1)
- Used when CrCl
Accumulation of metabolites + efficacy
Codeine, procainamide
Accumulation of metabolites + toxicity
Meperidine
Propoxyphene
Steps to adjusting dose
Obtain history and relevant demographic/clinical info Estimate CrCl Review current meds Calculate treatment regimen Monitor Revise
Intermittent + Dialysis
Maintain high drug concentration until dialysis, then drop
Continuous + Dialysis
More like normal kidney function so no adjustment
Drug characteristics that affect removal:
Molecular weight
Water solubility
Protein binding
VofD
Drugs with less clearance =
High molecular size/wt
Highly protein bound
High flux causes
clearance of more drug molecules
Increased flow rates =
increased clearance of drugs
Esp small molecules
Anticonvulsants
Phenytoin
