Many thanks to all of you who responded so quickly and comprehensively.
For those looking into this exchange in the future through the NMuser
archive: Look at Mats’ and Tim’s response first then at all the others.
There is not a single answer. I for my part will employ several techniques
with sens
Dear nonmemusers
In my PK modeling project, a drug (elimination: 100 % hepatic metabolism)
is given orally twice daily over a period of 10 weeks. 100 subjects
contribute daily trough concentrations. During this period, covariates vary
within subjects. Two covariates that are difficult to handle a
Dear Elisabet,
The most complete way to handle your problem would be to treat the
covariates as observations and build a separate model for them. Your
data set would change from wide to long format. So instead of having
ID TIME DV CYTC
1 0X1 Y1
1 1X2 Y2
you would have
ID TIM
Dear Elisabet,
In addition to Sebastian's answer, the indirect response model he mentions
is a model for the turn-over of the (induced) enzyme. Thus the half-life of
the enzyme you may be able to get info in literature on a reasonable value
(probably 1-3 days). This type of model was used in:
A m
