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Dear all,
I am working with bioequivalence trials and I have a question regarding
subject genotyping.
According to CPMP's note for guidance on this issue, genotyping may be
considered in bioequivalence studies for safety or pharmacokinetic
reasons. It is also stated that in cases where a drug is known to be
subject to major genetic polymorphism, studies could be performed in
panels of subjects with known phenotype/genotype to the polymorphism in
question.
Does this implicate that selection of study subjects on the basis of
genotype is allowed, or that genotype could be used for post-hoc
interpretation of the results?
Thanking you in advance,
Susana Almeida
Portugal
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We have published a poster at Annual meeting of ASCPT showing that
drugs with polymorphisms are no different from the other in terms of
intrasubject variability. Therefore, phenotyping and/or genotyping to
reduce sample size is not useful for crossover study; this could be
considered for parallel studies.
However, what the note for guidance suggest is that phenotyping and/or
genotyping could be use for safety reason (e.g.., use only extensive
metabolizers to reduce exposure) , or pharmacokinetic reason (e.g. have
one sampling startegy instead of multiple sampling startegy by using a
subgroup, or reduce washout by only using EM). The guidance is quite
flexible in Europe to allow genotyping a priori or posteriori; we have
seen both.
Sincerely,
Eric Masson, Pharm.D.
Senior Director, Scientific and Regulatory Affairs
Anapharm- member of SFBC International.
2050 Boul. Rene Levesque W,
Quebec, QC, Canada
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