PharmPK Discussion - Bioavailability study report for exam

• On 15 May 2010 at 00:00:01, Guillaume Marchais (guillaumemarchais17.at.gmail.com) sent the message
  

  
  Dear all,
  
  I'm a french student in pharmacy and for my exams I have to write a little expose about a bioavailability study.
  It's a randomised and cross-over assay.
  The molecule is injected (5mg) or swallowed (20mg) with a wash-out period of 14 days
  12 volunteers were involved in this study.
  The bioanalysis of volunteers's blood gave the concentration of the molecule at different times and for every volunteers.
  
  We used Winnonlin to do a non-compartmental analysis of the data (12 people, Concentration at different time)
  
  we have to calculate the bioavailability (and IC95%) of the oral pill, and do a PowerPoint presentation of the rundown of the study as if we were working in a real Pharmaceutic Lab.
  
  My questions are :
  - I've calculated the average of the Cmax and Tmax => I have to talk about them, haven't I?
  - Is it really necessary to talk about the half-life, Clearance, Distribution volume and elimination speed constant and say that the half-life = x, the clearance = y , distribution volume = z ..?
  if yes, winnonlin calculated them for each volunteer so do I have :
      - to calculate an average of them based on the winnonlin data results     - to calculate them using formulas like Cl=D/AUC ; Vd=Cl/ke ; HL=(ln2)*(Vd/Cl)
  - in winnonlin what's the difference between Vz and Vss?
  
  By advance, thanks a lot for your answers,
  Guillaume.
  
  

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• On 14 May 2010 at 18:56:22, Lye Weng Kit (kitlye.aaa.yahoo.com) sent the message
  

  
  Hi Guillaume,
  
  It is necessary to present the Cmax which is reflect the rate of absorption in bioavailability study.Vss is refer to volume of distribution in steady state after multiple doses. Based on your study design, it is sufficient to report the Vz.
   Lye
  
  

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• On 15 May 2010 at 01:48:02, Dimiter Terziivanov (terziiv.-at-.yahoo.com) sent the message
  

  
  Dear Guillaume,
  
  The answers to your well formulated questions depend on what you really want to do:
  
  1. a scientifically sound presentation, or
  2. a regulatory authorities oriented presentation as you deal with a BE study.
  To issue #1: Yes, I think you have to perform all steps as mentioned in your email.
  To issue #2: In this particular case you have to look at recently published EMEA Guidance on presenation of BE results for getting approval in EU. If the second hypothesis is going on you have to justify the sample size of 12 volunteers as well. There are well documented rules, from scientifically view point, how to cope wiht this issue.
  
  Crossing fingers and Good luck,
  Dimiter T.
  
  PS. As to your question regarding the difference between Vz and Vss you have already got the answer.   --
  Dimiter Terziivanov, MD,PhD,DSc, Professor
  Pharmacology and Clinical Pharmacology
  SOFIA UNIVERSITY "ST. KLIMENT OHRIDSKI"
  FACULTY OF MEDICINE
  1 Koziak str.
  1407 Sofia, BULGARIA
  
  

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