PharmPK Discussion - Dose proportionality

• On 17 Feb 2011 at 07:03:47, "Dr. Prasad Tata" (drprasadtata.-a-.yahoo.com) sent the message
  

  
  Hi:
   In dose escalation studies we routinely include placebos for capturing  safety info some groups analyze samples for concentrations (and they  usally turn out to be zeros), during the dose proportionality evaluation  do we include placebo as part of building models for evaluating dose  proportionliy or we exclude them?  Any advise is greatly appreciated.
   Prasad NV Tata, Ph.D., FCP
  2133 Seven Pines Drive
  St. Louis, MO 63134
  
  

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• On 17 Feb 2011 at 12:30:49, Leonid Gibiansky (LGibiansky.-a-.quantpharm.com) sent the message
  

  
  The following message was posted to: PharmPK
  
  The simple answer is no: placebo subjects should NOT be included into  the evaluation of the dose proportionality. However, I've recently seen  the case when you want to include these data. The drug was an endogenous  substance, and placebo subjects provided the baseline level. Only the  level above the endogenous level was dose proportional. If we would use  only those on the drug, analysis would show nonlinear kinetics.
  
  Leonid Gibiansky
  
  www.quantpharm.com
  
  

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• On 17 Feb 2011 at 13:45:26, deanknuth (deanknuth.aaa.jasperclinic.biz) sent the message
  

  
  The following message was posted to: PharmPK
  
  Leonid point can also apply when PD or biomarker measures are part of  the protocol.
  
  --dean
  DeanKnuth.-a-.jasperclinic.biz
  
  

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• On 18 Feb 2011 at 13:59:48, (Soujanya.Neni.-at-.sunovion.com) sent the message
  

  
  The following message was posted to: PharmPK
  
  Hi Prasad,
  As far as my knowledge, we do not include placebos in dose  proportionality analysis, as we normally do not include them in PK  parameters calculations.
  Thanks,
  Soujanya
  
  

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• On 11 Aug 2011 at 15:39:23, Brian Davies (brian.davies.aaa.THEMEDCO.com) sent the message
  

  
  Could anyone please supply me with the SAS code to analyse a parallel design, dose
  proportionality study using the power model?
  
  Thanks
  
  brian
  

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• On 12 Aug 2011 at 08:21:51, Peter Bonate (peter.bonate.-a-.gmail.com) sent the message
  

  
  Brian
  
  For a parallel design with no repeated measurements just use linear
  regression with Ln(AUC) as the dependent variable and Ln(dose) as the
  independent variable.
  
  proc reg;
     model lnauc = lndose;
  run; quit;
  
  that should do it.
  
  pete bonate
  
  

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• On 12 Aug 2011 at 13:38:26, (Soujanya.Sunkaraneni.-at-.sunovion.com) sent the message
  

  
  The following message was posted to: PharmPK
  
  Hi Brian,
  
  So you mean code for BE analysis or for regular PK dose proportionality analysis? Let me
  know.
  
  Thanks,
  Soujanya
  

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• On 12 Aug 2011 at 11:29:21, Brian Davies (brian.davies.-at-.THEMEDCO.com) sent the message
  

  
  The following message was posted to: PharmPK
  
  Peter
  
  Thanks for this. I was hoping to go one stage further and calculate the
  CIs. I have not kept up with the literature on the method but I believe
  that there have been a few publications since the original two
  
  Thanks
  
  brian
  
  

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• On 12 Aug 2011 at 12:03:33, Peter Bonate (peter.bonate.-a-.gmail.com) sent the message
  

  
  Change the code to this:
  
  proc
  
  reg; model y = x / clb alpha=0.10; run; quit;pete
  
  

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