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PHX8: Half Value Duration (HVD) and Plateau Time (T75%)

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#1 Helmut Schütz

Helmut Schütz

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Posted 30 October 2017 - 02:46 PM

Dear all,

in previous releases of PHX/WNL the intersection of the profile with a fixed value was always performed by linear interpolation (increasing concentrations) and by log/linear interpolation (decreasing concentration) – which IMHO, is the method of choice.
This lead to confusion in the past since this method was independent from the selected AUC calculation. Since v8.0 the method observes the chosen AUC-rule.
Calculating the Occupancy Time (time interval where concentrations are at least some limiting value, e.g., the MIC) is trivial. However, the Half Value Duration (HVD, interval where C ≥ 50% Cmax) or the Plateau Time (t75%, interval where C ≥ 75% Cmax) needs two steps.

  1. Get the subject’s Cmax and calculate the required fraction(s).
  2. In the final NCA > Therapeutic Response > map the calculated fraction to Lower and Cmax to Upper.

It is not possible to calculate HVD and t75% simultaneously. If you need both, run two NCAs and join their results.
Attached File  Half Value Duration and Plateau Time.phxproj   1.18MB   296 downloads

 Best regards,


#2 Simon Davis

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Posted 02 November 2017 - 04:21 PM

Thanks for your feedback as always Helmut.  Your comments have been added to an existing issue QC16467.



#3 Angus McLean

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Posted 06 November 2017 - 05:59 PM

Attached File  PD metrics for Ciprofloxacin.pdf   63.35KB   347 downloadsHelmut thank you for this stimulating  post:  when I look at this work I think in the direction anti-infective metrics for efficacy like for example Cmax/MIC etc. that can be applied to drugs like ciprofloxacin.  I attach a paper on Cipro.





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