PharmPK Discussion - 125I-peptides for tissue distribution studies in animals

• On 8 Jun 2011 at 15:01:56, Yulan Qi (yulan.qi.at.gmail.com) sent the message
  

  
  I am planning to conduct tissue distribution studies for a peptide  containing 40 amino acids. 125 iodination was chosen as the method for  peptide labeling. I have a couple of questions regarding how to conduct  the studies.
  
  1.      In ICH Topic S 6, it's stated that "When using radiolabeled  proteins, it is important to show that the radiolabeled test material  maintains activity and biological properties equivalent to that of the  unlabeled material". I am wondering practically, what techniques are  people frequently used to fulfill the regulatory requirement that the  125I-peptide maintains activity and biological properties equivalent to  that of the unlabeled peptide. I have searched literatures and hardly  found anyone mentioned that they had done this before using  125I-biologics in animal tissue distribution studies.
  
  2.      The intended clinical administration route for this peptide is  subcutaneous injection. However, the bioavailability of this peptide by  SC is less than 10%. I am wondering, whether I can use IV injection of  this peptide in the tissue distribution studies.
  
   Any comments or suggestions are highly appreciated. Since I cannot  receive emails from the PharmPK discussion list since this April, please  cc my email address (yulan.qi.at.gmail.com) if you reply.
  
  Thanks,
  Yulan Qi
  
  

  Back to the Top

Copyright 1995-2011 David W. A. Bourne (david@boomer.org)