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The following message was posted to: PharmPK
Dear Colleagues,
Elderly cancer patients usually suffer from other complications such as
hypertension, lipid disorder, seizure disorder or brain metastases. Most
of the medications used for correcting these disorders will interact
(inhibitor, inducer or substrate) with cytochrome P450 enzymes. In
conducting PK trials, how restrictedly should we set the criteria for
patient exclusion from the study with respect to concomitant drugs?
By going back to the literature, you can easily come up with several
hundreds of compounds/drugs interacting with P450 enzymes, which at
least a large number of these drugs would be applicable in the specific
patient population of interest; this will slow down patient accrual. Of
course this dose not mean that a particular isoform is the principle
metabolic pathway or that alterations in the metabolic rate in vivo will
have a large effect on PK of the drug. So, what are the criteria for
screening the patients for inclusion or exclusion in the trial with
regard to other simultaneous drugs that they are receiving?
Rostam
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The following message was posted to: PharmPK
Hi Rostam:
It would not be practical to exclude patients based on concomitant
medications.
If possible, you can use sparse PK sampling in your studies and use
population PK analysis to screen for potential drug-interaction in your
patient population. Please see the FDA guidance on pop pk analysis to
help you design your study. http://www.fda.gov/cder/guidance/1852fnl.pdf
Best regards,
Sam Liao, Ph.D.
PharMax Research
270 Kerry Lane,
Blue Bell, PA 19422
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