PharmPK Discussion - Determination of CLint from Km and Vmax

• On 29 Jul 2012 at 11:01:59, amrita saxena (amritasaxena5.at.yahoo.com) sent the message
  

  
  Dear all,
  
  I am calculating CLint for various standard CYP substrate through metabolite
  formation approach.
  
  I am using GraphPad Prism software for the calculation of Km and Vmax through
  the initial velocity vs substrate conc. plot (Michaelis menten)
  
  My queries are:
  
  (1)  Is there any particular weighing method (or change in other settings)  that
  i have to select while analyzing data through non linear regression in software
  to calculate Km and Vmax
  
  (2)   the formula to calculate CLint is Vmax / Km. The unit of Vmax is(uM/min)
  and Km is (uM) then how come In literature the unit of CLint is uL/min x mg in
  case of microsomes and uL/min x pmol in case of rec CYPs
  
  (3)   If there is any normalizing factor in terms of protein used in incubation
  / vol of incubation medium. If any please let me know how to implement it in
  case of microsomes and rec CYPs separately and at which stage.
  
  Waiting for your valuable suggestions. Thanks in advance.
  
  Thanks and Regards
  Amrita Saxena
  
  

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• On 30 Jul 2012 at 22:23:14, Ravi Talluri (ravitalluri.at.gmail.com) sent the message
  

  
  Hi,
  
  Vmax is amount of product formed per min or per hour..so it should be umol/min
  not the concentration uM/min. You can normalize it per mg of protein..with this
  as you may already know you can scale your CLint to CLhep.
  
  Thanks
  Ravi
  
  GlenMark Pharmacueitcals
  India
  

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