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How to count on SS for L-Dopa


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#1 vetpharma

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Posted 22 June 2022 - 02:47 PM

Hi,

 

I am modeling the L-Dopa Cp-time profile following po administration of Sinemet. The dosing interval is q3h from morning to evening. In this study, blood samples were taken on day 14. The Cp-time profile, model and other data is in the model (attachment). Adding ADDL is working pretty well, however, in the morning there are some carryover from last day so the concentration is not 0 in the first administration on Day 14. How can I count for this non 0 concentration. Should I add SS to the dosing (It doesn´t make sense to me, since we are not at SS and most prob model will give error since it has not been on SS at that time)?

I would appreciate it if you kindly help me with this issue.

 

 

 

 

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#2 bwendt@certara.com

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Posted 23 June 2022 - 12:55 PM

Hi,

 

if the concentration is not at steady state, you need to let the program know that there have been preceding doses before your observations. In that case I would use a combined ADDL dosing scheme:

 

comb_ADDL.png

 

The fit does not look too nice, but I haven't rerun the model, just a simulation with the existing parameter estimates:

 

profile.png


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#3 vetpharma

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Posted 23 June 2022 - 04:51 PM

Hi,

 

if the concentration is not at steady state, you need to let the program know that there have been preceding doses before your observations. In that case I would use a combined ADDL dosing scheme:

 

attachicon.gifcomb_ADDL.png

 

The fit does not look too nice, but I haven't rerun the model, just a simulation with the existing parameter estimates:

 

attachicon.gifprofile.png

Very Nice. Thanks. 






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