PharmPK Discussion - Radioactivity in feces following iv dose

• On 28 Sep 2001 at 18:18:42, JYOTI PALIWAL (JYOTIP.-at-.Ranbaxy.co.in) sent the message
  

  
  Dear Group,
  
  I am working on a NCE belonging to high permeability class, expected to be
  absorbed almost 100%. It undergoes significant first pass effect with
  absolute bioavailability less than 5%. During excretion balance study of
  this NCE using 14 C labeled compound, we observed that % dose excreted in
  feces following an intravenous dose was almost twice as much after an equal
  oral dose.  The compound is excreted in Urine as well and the total recovery
  in 3 days is > 90%. How can it be explained ? Thanks all in anticipation of
  valuable response.
  
  Jyoti Paliwal, Ph.D.
  
  

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• On 29 Sep 2001 at 22:27:25, Spiresgate.aaa.aol.com sent the message
  

  
  Your statement that recovery is > 90% suggests you are speaking of
  total radioactivity.  If the amount in faeces is also total
  radioactivity then you are looking at mixtures of possibly a whole
  range of different compounds with different solubilities, transport
  properties etc.  For example, first-pass metabolism may convert most
  of the material to water-soluble metabolites readily excreted in
  urine.  The question of why you get twice as much total C14 in faeces
  after intravenous dosing therefore does not arise.
  
  Joe Chamberlain
  
  

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