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Dear Sir,
I would appreciate very much if you could help me to answer the following
question:
Could the HPLC-MS technique substitute the need to use a reference standard
to QUANTITY the drug active metabolite(s) in the Bioequivalence studies? We
are trying to figure out the answer by searching the FDA, ICH and other
regulation, but we cannot find an answer for this particular question. We
are planning to conduct a Bioequivalence study on a Generic that has an
active metabolite which has no available reference standard in the market.
There have been suggestion that it would be acceptable to use LC-MS to
quantity the active metabolite for this drug, we do know that LC-MS could be
used to identify an active metabolite but we do not see how this technique
would be applied to quantity, and if this approach would be acceptable form
the regulation point of view.
Looking forward to hearing form you,
Dr. Isam Salem
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Dear Dr. Salem:
You are correct in thinking that LC/MS/MS can be used to quantitate the active
metabolite in your clinical trials samples. However, you really do need to
obtain the metabolite first. We do not generally synthesize the metabolites
which we use, but there are several very good (and several not very good) small
quantity manufacturers of drug mets. In many ways, it depends upon the
particular molecule needed as to who should be your contractor. Of course, you
will need to characterize and validate the product before you use it.
Robert K. Lantz, Ph.D.
Director
Rocky Mountain Instrumental Laboratories
108 Coronado Ct.
Ft. Collins, CO 80525
970-266-8108
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David Bourne (david@boomer.org)