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Error in NCA Steady-state dosing interval

winnonlin nca steady-state

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#1 sylviachen

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Posted 10 April 2019 - 01:50 PM

Hi all, 

 

I'm fairly new to WNL and have been using Phoenix 8.1 just recently. I've mostly worked with single-dosing using NCA.

 

I have tried to combine single-dosing (0-24hours) and repeated dosing data (steady-state timepoints) in one full analysis but I keep encountering this error msg "ERROR: 14061: No data in steady state dosing interval; program terminating." Although I am able to execute, I am prompted to see text output for details as final parameters could not be generated.

 

I have indicated tau to be 24 hours, since drug was administered once per day; continuously for 14 days. 

Attached File  PK Winnonlin input-Steady state.xlsx   11.39KB   223 downloads

Time points for first 24 hours are 0, 15min, 30min, 1h, 2h, 4h, 6h, 8h, 8h, 24h. Steady-state is expected after day 5. Subsequent sampling were taken at day 6, day 13 and day 20. 

 

Can someone tell me what I'm doing wrong here?

 

Thanks in advance!



#2 Helmut Schütz

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Posted 10 April 2019 - 05:44 PM

Hi,

 

please upload your project (and not just the data). We have no crystal ball. ;-)


 Best regards,
Helmut

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#3 sylviachen

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Posted 11 April 2019 - 05:37 AM

Oops, sorry about that!

here it is! Attached File  Drug PO-steadystate.phxproj   406.27KB   506 downloads

 



#4 Helmut Schütz

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Posted 11 April 2019 - 03:48 PM

Hi Syvia,

 

Oops, sorry about that!

here it is! attachicon.gifDrug PO-steadystate.phxproj

 

THX! I see that you mastered one of the secrets: Always give the dose in the same mass-unit as the concentration. :) 

You sorted both for SN and Subject_ID. That’s not necessary because they are unique. Any one of them is enough.

Now for the problem – which is impossible to solve with NCA and your data. In the last interval you have just one concentration >LOQ. Hence, the Error message is correct.

You could only try modeling. BTW, the concentrations of the first subject decreased. Maybe you have to deal with saturation.

For the future: If possible, sample the entire steady state profile. Try to get at least the last three pre-dose samples (in your example days 18, 19, 20).

 

Hope that helps.


 Best regards,
Helmut

http://forum.bebac.at/


#5 sylviachen

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Posted 12 April 2019 - 01:51 AM

Hi Helmut, 

 

Thanks so much for your input. We have chosen the following time points on the basis that steady-state will be reached by Day 5. (ie. Day6, Day 13, Day 20).

 

Could you advise how I could do modeling to make use of the data after 24hours? I've only done NCA and have not wandered into the realm of modeling yet.

 

Thanks again.

Best,
Sylvia

 

Hi Syvia,

 

 

THX! I see that you mastered one of the secrets: Always give the dose in the same mass-unit as the concentration. :)

You sorted both for SN and Subject_ID. That’s not necessary because they are unique. Any one of them is enough.

Now for the problem – which is impossible to solve with NCA and your data. In the last interval you have just one concentration >LOQ. Hence, the Error message is correct.

You could only try modeling. BTW, the concentrations of the first subject decreased. Maybe you have to deal with saturation.

For the future: If possible, sample the entire steady state profile. Try to get at least the last three pre-dose samples (in your example days 18, 19, 20).

 

Hope that helps.







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