TTT method for lambda_z estimation [🇷 for BE/BA]

posted by d_labes  – Berlin, Germany, 2008-09-30 16:48 (6055 d 00:49 ago) – Posting: # 2449
Views: 59,991

Dear Yung-jin Lee,

❝ We have some initial results for the estimation of lambdaz using TTT method.


Congratulation.

Because I'm not an useR! I cannot totally follow your code.
But I think your implementation is the TTT rule as invented: Take all points after 2 x tmax for estimating lambdaZ. Am I right?

If yes, I wish to specify my suggestion further:
The TTT rule is only valid if the concentration time course resembles a one-compartmental curve (see the paper of the inventors for this1)).
Thus my suggestion is to restrict the maximum number of time points to use for lambdaZ estimation to the TTT range and in that range apply the search for points with adjR2 or whatever fit criterion you wish to apply.

I have no systematic evidence but after some cursory case evaluations I intuitively feel (ok this is not very scientific :-D) that this method should choose reasonable number of points for the terminal phase, although in cases where the curves do not resemble one-compartmental shape.

1) Scheerans C, Derendorf H and C Kloft
Proposal for a Standardised Identification of the Mono-Exponential Terminal Phase for Orally Administered Drugs
Biopharm Drug Dispos 29, 145–157 (2008)
—
Regards,

Detlew
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