NCA analysis with a specific study design (bolus + 1 h infusion + 6 h infusion)

Phoenix Certara Forums Phoenix WNL basics
1

Hi,

I have to perform NCA analysis after intravenous administration:

  • bolus followed by a 1 h infusion followed by a 6 h infusion

I use Phoenix 6.3 and I have the concentration at the end of the first infusion, 2 concentrations during the 6 h infusion and 3 concentrations after the second infusion.

I have no sample at time 0.

  • Using Phoenix, without any information in the dosing sheet, Phoenix uses a concentration at 0 at time = 0

  • Using Phoenix, with all the information in the dosing sheet (short infusion for the bolus, 1h infusion and 6 h infusion), Phoenix doesn’t uses a concentration at time = 0 and the AUClast calculated corresponds to the AUC1-last.

What is the best thing to do ?

Thanks

Nathalie

2

Hi Nathalie, I guess the question is what do you want to achieve, NCA is really only for single dose events when you come to calculate things like Clearance etc.

You could get an approximation my making it one 7 hour infusion for NCA and requesting partial areas, but overall I’d probably model this data. Perhaps you can give more specific questions on what you want to report and why?

Simon.

3

Hi Simon,

I just want to report PK parameters: AUCt, AUC, t1/2, z, CL…

Nathalie

4

That is your problem, calculations of Clearance are dose dependent, and for NCA the state is assumed to be first dose or at steady-state. So anything you do with your data is going to be an assumption. If you post a PHXPROJ, or just the CSV with an example profile we can show an example but the results would have the above caveats.

Simon