PharmPK Discussion - Conversion of lambdas to rates

• On 9 Jul 2013 at 23:14:45, Batul Parta (batulparta.-at-.yahoo.com) sent the message
  

  
  Dear all,
  
  I am reading an article where the authors report modeling results of data after iv infusion. A two
  compartment model fitted the data and they present lambda1, lambda2, CL, Vdc and Vdss. Could someone
  please provide a reference on how to convert lambda1 and lambda2 to k12 and k21? I want to simulate
  different doses using this model and am not sure how to use the lambdas for simulations.
  
  Thank you in advance,
  
  BP
  Batul Parta 
  
  

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• On 10 Jul 2013 at 08:45:26, Mukul Minocha mukul.minocha.-at-.gmail.com sent the message
  

  
  Hi Batul,
  
  The relationship is as follows:
  
  α + β = kel + k12 + k21
  α * β = kel * k21
  
  k12 = (rate constant from Central to Peripheral cmt)
  k21 = (rate constant from Peripheral to Central cmt)
  kel = CL/Vc
  
  usually, α and β are calculated, given rate constants as:
  
  [(α + β)+/- (sqrt(α + β)^2 - 4*α * β)]/2
  
  More information could be found with an example at
  http://www.boomer.org/c/p4/c19/c19.pdf
  
  Best
  
  Mukul Minocha
  CTM
  University of Maryland Baltimore
  mukul.minocha.-a-.gmail.com
  
  [I'm not sure if the alpha and beta symbols will get through on the new system. We'll  give it a
  try. Also, other links that might be useful is http://www.boomer.org/c/p4/c19/c1902.html
  and http://www.boomer.org/c/p4/c19/c1903.html
  - db]
  
  

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• On 10 Jul 2013 at 08:47:53, Ankur Sharma ankur-sharma.-a-.ouhsc.edu sent the message
  

  
  Dear Batul,
  
  Kindly see the following article and the reference by Wagner, 1975 cited in
  the article to calculate the micro rate constants (K12, K21) from the
  hybrid or macro rate constants (lambda1, lambda2). This article helped me
  in calculating the macro rate constants.
  
  "Calculating the hybrid (macro) rate constants of a three-compartment
  mamillary pharmacokinetic model from known micro-rate constants" in, Journal
  of Pharmacological and Toxicological Methods 49 (2004) 65–68.
  
  Hopefully it works for you.
  
  All the best !!
  
  Thank you and best regards,
  
  -Ankur
  
  Ankur Sharma
  Graduate Research Assistant, College of Pharmacy
  University of Oklahoma Health Sciences Center
  1110 N Stonewall Avenue
  Oklahoma City, OKC, OK 73117
  Email: ankur-sharma.at.ouhsc.edu
  
  

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