PharmPK Discussion - Creatinine Clearance

• On 6 Feb 1996 at 12:55:47, SUTTLE Ben (suttleab.-a-.usrd3.zen.com) sent the message
  

  
  PharmPK subscribers,
  
  I am trying to determine the effects of age and renal function on the
  clearance of a drug.  The Jellife and Cockcroft and Gault methods to
  determine creatinine clearance from serum creatinine concentrations include
  the patients age in the calculations.  The inclusion of age in the
  creatinine clearance calculation may be confounding the determination of the
  effects of age and renal function on drug clearance.  Are there any other
  accurate methods for calculating creatinine clearance from serum creatinine
  concentrations that do not include subject age in the equations?
  
  Thanks,
  
  Ben Suttle
  Zeneca Pharmaceuticals
  
  from: SUTTLE Ben 
  
  

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• On 7 Feb 1996 at 10:04:10, "Michael Burton" (michael.burton.at.DISPATCHER.NET.uokhsc.edu) sent the message
  

  
  Because of the age related decline in renal function, I think that it will be
  difficult to separate the determination of renal function from a serum
  creatinine value in a predictive algorithm without considering age.  I would
  suggest that 8 or 24 hour urine collections be performed in an experimental
  situation to separate the effects of age from renal function.  Although the
  current gold standard is probably non-radioactive iothalamate clearance using
  a continuous infusion with three timed urine collections and mid-point serum
  concentrations over 3 hours.
  
  

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• On 8 Feb 1996 at 12:26:09, aharralson.at.vms1.cc.uop.edu sent the message
  

  
  Creatinine clearance estimates are based on the input/output principle.  The
  role of age, weight, etc. in the equations are simply estimates of the rate
  of endogenous production of creatinine which is the rate in (input).  The rate
  out (output) is the creatinine clearance, and the ratio of the two is equal to
  the serum creatinine.
  
  Creatinine porduction is know to decrease with age.  If you leave it out of
  the estimation formula, you are neglecting a known variable.  Why not measure
  drug clearance or elimination directly?  I have published a couple of papers
  in which we measured drug clearance directly using limited sampling.
  
  Art Harralson, Pharm.D., BCPS
  Professor and Vice-Chairman
  University of the Pacific
  School of Pharmacy
  AHARRALSON.aaa.UOP.edu
  
  

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