PharmPK Discussion - Affinity constant

• On 14 Mar 1996 at 11:00:39, "N. Van Brandt" (vanbrandt.-at-.fatc.ucl.ac.be) sent the message
  

  
  
  I have completed a study about unbound fraction of midazolam and sufentanil
  in ICU.
  
  I have studied 50 patients divided in 5 groups (control, cardiac, hepatic,
  renal and pateint under ECMO).
  For all patients I have a minimum of 20 oberservations of free fraction and
  protein concentration.
  
  I have determined free fraction by equilibrium dialysis for both drugs,
  I have also determined albumin and AAG in serum.
  
  May I calculate nKA by the formula fu = 1/ (1+nKa.Pt) ? Will nKa (or K')
  parameter
  reflect the affinity of drugs for proteins because if Ka increase and the
  number of
  binding sites decrease. Finallly, nKa won't change.
  
  Because I think that with the parameter I have, I cannot determine n and Ka
  separetly.
  
  Any help ?
  ----------------
  Nicolas VAN BRANDT (tel: 32.2.764.11.11 bip:7353)
  Pharmacist
  Lab. of Pharmacokinetics (Prof R.K. Verbeeck)
  UNIVERSITY OF LOUVAIN
  Av. E. MOUNIER, 73-55
  1200 Brussels, Belgium, EUROPE
  Belgium,
  Europe.
  vanbrandt.-a-.fatc.ucl.ac.be
  
  from: "N. Van Brandt" 
  
  

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