PharmPK Discussion - Estimating bioavailability of a drug that must be hydrolyzed prior to being active

• On 24 Nov 1998 at 14:17:22, "Lakritz, Jeffrey" (LakritzJ.aaa.missouri.edu) sent the message
  

  
  I have a question regarding the calculation of bioavailability of
  erythromycin after giving erythromycin estolate.  Using HPLC to determine
  both the erythromycin A and the ester simultaneously, we are now presented
  with how to determine the bioavailability of the drug (active drug and the
  ester in plasma).  We have given the drug intravenously to compare the oral
  with IV dosing, but when we compare AUCoral/AUCiv we come up with a
  bioavailability of >100% (when you include the AUC of both compounds
  monitored simultaneously).  Is there a relationship (fudge factor) that is
  necessary to get a more believable number?
  Any help is appreciated.
  
  Jeff Lakritz
  Dept VMS
  University of Missouri-Columbia
  Columbia, MO. 65211
  573-882-3235
  LakritzJ.at.missouri.edu
  
  

  Back to the Top

• On 25 Nov 1998 at 11:28:15, Fritz Sorgel (ibmp.-a-.osn.de) sent the message
  

  
  Dear Jeff,
  what did you actually measure ? Parent erythromycin propionate or erythromycin
  free base? The appropiate determination of parent and active base may be
  extremely difficult. We analyze E.- propionate in the presence of erythromycin
  with LC-MS/MS.Call me if you have questions.
  
  Fritz Sorgel; Nurnberg, Germany
  Phone: 011 49 911 518 280
  Fax: 011 49 911 518 2820
  
  

  Back to the Top

• On 30 Nov 1998 at 12:56:18, Leslie Carstensen Floren (leslief.-a-.itsa.ucsf.edu) sent the message
  

  
  Dear All,
  as far as I know, erythromycin given intrsvenously is actively secreted
  into the gut.  I'm sorry I don't have the references that describe this
  phenomenon, but this could be a reason that your calculation of F is off.
  LEslie C. FLoren, Pharm.D.
  
  

  Back to the Top

PharmPK Discussion List Archive Index page

Copyright 1995-2010 David W. A. Bourne (david@boomer.org)