WinNonlin: NCA of multiple dosing plasma PK profile [Software]

posted by bobmarlo – 2017-01-15 18:22 (2629 d 16:23 ago) – Posting: # 16953
Views: 12,194

I want to do non-compartmental analysis on plasma PK data from two cycles of short infusions using WinNonlin. Unfortunately, I do not have the plasma concentrations from first cycle and the only available concentrations are from second cycle. Doses used in first and second cycle are same, however, the predose conc. for second cycle is 10. Concentration for first time point of second cycle being 10 (not 0 at 0 hr for second cycle) or >LLOQ although close to LLOQ (with Cmax of 200, last measured conc. of second cycle 10, achieving steady state), makes the baseline look like 10. I want to know if NCA can be done directly on this data set from second cycle? Or it may lead to error because of drug still being present in the system before second infusion? I am primarily concerned about parameters including terminal t1/2, AUClast & inf, CL, MRT, Vss? I believe I cannot subtract baseline value from all the samples as commonly done in case of endogenously produced molecules and therefore all the listed parameters except t1/2 may not accurately represent drug profile. What would be the best approach to analyze such data to get parameters from second cycle?
Thanks


Edit: Category and subject line changedchanged; see also this post #1 and #2. [Helmut]

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