Washout based on mean ± SD of t½ [Design Issues]

posted by Helmut Homepage – Vienna, Austria, 2022-09-26 19:35 (134 d 06:06 ago) – Posting: # 23322
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Hi Imph,

❝ I would like to know if this method can be applied to each pharmacokinetic measurement, for example to determine the duration of the sampling (5 x t1/2) or to calculate the predose limit of 5% Cmax when the Cmax is provided in the literature under mean+/-SD.

In principle, yes. I prefer to start with a single dose profile (even if read from a published figure) and perform nonparametric superposition.

❝ Why plan for 95% coverage (z0.95 = 1.96), is it related to alpha =5%.

Convention. You can use a more conservative value.

❝ In the reference you gave, a normal distribution is assumed, but pharmacokinetic measurements do not generally follow a normal distribution but a log-normal one. Does this method still apply?

You are right. But if the arithmetic mean ± SD is all you have… If you have results for the geometric mean, better, of course.

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