title: Drug therapy management in patients with renal impairment: how to use creatinine-based formulas in clinical practice.
abstract: OBJECTIVE
  The use of estimated glomerular filtration rate (eGFR) in daily clinical practice.
  
  
  METHODS
  eGFR is a key component in drug therapy management (DTM) in patients with renal impairment. eGFR is routinely reported by laboratories whenever a serum creatinine testing is ordered. In this paper, we will discuss how to use eGFR knowing the limitations of serum creatinine-based formulas.
  
  
  RESULTS
  Before starting a renally excreted drug, an equally effective drug which can be used more safely in patients with renal impairment should be considered. If a renally excreted drug is needed, the reliability of the eGFR should be assessed and when needed, a 24-h urine creatinine clearance collection should be performed. After achieving the best approximation of the true GFR, we suggest a gradual drug dose adaptation according to the renal function. A different approach for drugs with a narrow therapeutic window (NTW) is recommended compared to drugs with a broad therapeutic window. For practical purposes, a therapeutic window of 5 or less was defined as a NTW and a list of NTW drugs is presented. Considerations about the drug dose may be different at the start of the therapy or during the therapy and depending on the indication. Monitoring effectiveness and adverse drug reactions are important, especially for NTW drugs. Dose adjustment should be based on an ongoing assessment of clinical status and risk versus the benefit of the used regimen.
  
  
  CONCLUSIONS
  When determining the most appropriate dosing regimen serum creatinine-based formulas should never be used naively but always in combination with clinical and pharmacological assessment of the individual patient.
authors: Radboud Institute for Health Sciences, IQ healthcare, Radboud University Medical Center, Nijmegen, The Netherlands. Willemijn.Eppenga@radboudumc.nl.
authors: Willemijn L
authors: WL
authors: Eppenga
authors: Departments of General Internal Medicine and Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, The Netherlands.|Department of Clinical Pharmacy, Canisius Wilhelmina Hospital, Nijmegen, The Netherlands.
authors: Cornelis
authors: C
authors: Kramers
authors: Hospital Pharmacy 'ZANOB', 's-Hertogenbosch, The Netherlands.|Division of Pharmacoepidemiology and Pharmacotherapy, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Utrecht, The Netherlands.
authors: Hieronymus J
authors: HJ
authors: Derijks
authors: Radboud Institute for Health Sciences, IQ healthcare, Radboud University Medical Center, Nijmegen, The Netherlands.
authors: Michel
authors: M
authors: Wensing
authors: Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors: Jack F M
authors: JF
authors: Wetzels
authors: Radboud Institute for Health Sciences, IQ healthcare, Radboud University Medical Center, Nijmegen, The Netherlands.|Department of Pharmacy, Radboud University Medical Center, Nijmegen, The Netherlands.
authors: Peter A G M
authors: PA
authors: De Smet
mesh_terms: D003404:Creatinine / Q000097:blood*; D005919:Glomerular Filtration Rate; D006801:Humans; D054539:Medication Therapy Management; D051437:Renal Insufficiency / Q000097:blood / Q000378:metabolism / Q000503:physiopathology*
chemical_list: D003404:Creatinine
keywords: Adverse drug reaction; Drug dose; Glomerular filtration rate; Renal function; Therapeutic window