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artifact? [PK / PD]

posted by Helmut Homepage - Vienna, Austria, 2017-03-17 13:09  - Posting: # 17160
Views: 802

Hi javier,

» in the single dose pk study (with full pk sampling ) the half life was reported in 17 days, while in the multiple dose study (with sparse sampling) the half life was reported in 26 days, How could it be possible?

First of all I don’t think that half lives are normal distributed. Hence, I don’t like the reported arithmetic means. ;-) There were different number of patients enrolled in the cohorts. Therefore, you should use weighted means which are 22.0 days (single dose) and 26.1 days (multiple dose). Such a difference does not worry me. Furthermore, half lives in the SD study were obtained by NCA and in the MD study by a two-compartment PopPK model. Since there is substantial accumulation it might be possible that in the SD study the terminal phase was not completely “visible” – especially after low doses and NCA underestimated the true (i.e., higher) value.

» How would you calculate the steady state in this situation?

What do you mean by that?

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Helmut Schütz 
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