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Dear Forum,
We are planning a relative bioavailability study between a novel peroral
formulation and an established innovator reference; the two formulations
are
expected not to be bioequivalent. The trial is requested to be designed
such
that it meets the requirement that "the SE around the geometric mean
ratio
should be no more than 20%". We know the ANOVA-MSE from previous
XO-studies
with related formulations. How should we estimate the sample size?
Kind regards - Christian
PD Dr. med. Christian de Mey
ACPS - Applied Clinical Pharmacology Services
Philippsring 11, D-55252 Mainz-Kastel, Germany
c.demey.at.acps-network.com
http://www.acps-network.com
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Hi Christian,
Usually the confidence interval (90% or 95%) is used as a measure of
precision. The CI (and SEM) get smaller and smaller with increasing the
sample size. So if you set a certain width of the CI (20% translates to
a half-width of 0.223 in log-space), the corresponding sample size is
easily calculated. Can be done using R, nQuery SAS...
Regards,
Peter
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