PharmPK Discussion - Protein precipitation

• On 11 Oct 2009 at 17:17:53, Hariprabu N (n.hariprabhu.at.gmail.com) sent the message
  

  
  The following message was posted to: PharmPK
  
  Dear friends
             Whether any other solvent is there to precipitate a plasma
  protein other than acetonitrile and methanol in bioanalysis
  
  with regards
  hari
  
  

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• On 12 Oct 2009 at 20:19:52, veeravalli vijay bhaskar (veeravalli.bhaskar.-a-.gmail.com) sent the message
  

  
  Dear Hari,
  
                   you can use acids such as TCA for precipitating the
  protein. most of the concentrated acids has the potential to
  precipitate the protein as acids provide pH below the isoelectric
  point of the proteins.
  
  with regards,
  
  veeravalli vijaya bhaskar
  
  

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• On 12 Oct 2009 at 20:24:05, veeravalli vijay bhaskar (veeravalli.bhaskar.at.gmail.com) sent the message
  

  
  dear all,
  
                 if free and bound forms both get extracted in case of
  protein precipitation, then why is protein precipitation prefered for
  highly protein bound compounds. kindly answer my query. thanks in
  advance.
  
  with regards,
  
  veeravalli vijaya bhaskar
  
  

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• On 12 Oct 2009 at 14:22:50, sunil battu (sunilkumarbattu.aaa.gmail.com) sent the message
  

  
  Ice cold glacial acetic acid (10% v/v) can be used for protein
  precipitation.
  
  Regards,
  
  Sunil
  
  

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• On 13 Oct 2009 at 15:14:49, pnnce.-a-.lupinpharma.com sent the message
  

  
  The following message was posted to: PharmPK
  Dear Bhaskar,
  
  In bioanalysis, we always quantify the total drug i.e bound and
  unbound. All the methods used for extraction of biological samples
  (Plasma, serum, microsomes, S9,cell extracts) like Protein
  precipitation (by Acetonitrile, Methanol, etc), Liqiud - Liqud
  extraction ( by Ethyl acetate, TBME, Diethyl ether)  and Solid phase
  extraction (by using HLB Cartridges) would extract the total drug
  present in that sample. Methods in general primarily selected on the
  basis of recovery of analyte by individual methods. Some times because
  of interferences, you have to select method with lowest interferences
  with analyte retation.
  ( In general, all the methods of extraction will always give you total
  drug present in the matrix)
  
  The experiments, where you have to quantify the free fraction, then
  there is need to use suitable devices ( Ultrafiltration devices like
  Nanosep, etc) which seperates bound and unbound drugs. you can use
  protein free fraction to find unbound and bound form of drug.
  
  I hope , this will help you.
  
  Thanks
  
  Vinod and Sadanand Mallurwar
  
  Novel Drug Discovery & Development
  Lupin Ltd. (Research Park)
  46A/47A, Village-Nande,
  Taluka- Mulshi
  Pune-411 042, India.
  
  

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• On 13 Oct 2009 at 10:56:19, "Bioconsul09" (Bioconsul09.aaa.cox.net) sent the message
  

  
  The following message was posted to: PharmPK
  
  No!  100% recovery is more rare than reported in the previous
  discussion. Protein precipitation with organics or acid alone may not
  liberate all of the drug.   Often some additional agent may need to be
  added.  And we need to be careful of clarifying relative and absolute
  recovery.  Acetic acid is a weak protein precipitating agent-chilled
  or not.  Perchloric acid or TCA are better, but then you also need to
  think about what happens downstream, e.g., MS in negative mode.
  Additional steps may be needed to neutralize or remove the acid.  In
  addition, the drug may be partitioned between cellular and plasma
  components.
  
  

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