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I would like to know which product should be the reference in the following
bioequivalence study:
Suppose a multinational produces one of its drug products with a subsidiary
in a third world country. That product does not need to have BE study, since
they produce the same formulation of the parent company. A generic wants to
put the same drug with his own formulation to market. Naturally, he has to
conduct a BE study with the innovators' product. Which should be the
reference? The product in the innovators' own country, or the one produced
by the subsidiary?
Suppose the subsidiary's product has a BE of 85 %(which is not determined,
anyway). And the generic product has 85 % BE versus the subsidiary product.
Then the generic has a BE of 72 %(0.85*0.85), which is not acceptable. The
converse is also true, of course.
That brings another issue to focus: Being a reference and being a
bioequivalent product are entirely different concepts and one cannot/should
not substitute one for the other. I would like to hear opinions on this
issue. Thanks.
Ilbeyi Agabeyoglu
Gazi Univ.Fac.Pharmacy
Ankara,Turkey.
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The reference product should be whatever version of the innovator's
product is being sold in the country that you plan to sell the
generic product.
Secondly, you are justified with respect to your concerns regarding
the fact that a comparison to the reference product is not
necessarily the same as a comparison to a product that has been
demonstrated to be bioequivalent to the reference. 'A' may be
bioequivalent to 'B', and 'B' may be bioequivalent to 'C', but that
doesn't mean 'A' will be bioequivalent to 'C'. You run the risk of
introducing bioavailability 'creep'. That is why regulatory agencies
ask that all generic products be compared to a standard reference
product e.g., 'A' vs. 'B' and 'A' vs. 'C'.
John Gordon
Wolfville, N.S.
Canada
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The following message was posted to: PharmPK
Dear Ilbeyi:
I agree absolutely with you.
In fact a similar situation is: If you have a Generic A which is
bioequivalent to the Reference (in the upper limit) and a generic B which is
bioequivalent with the reference (in the lower limit), then you can easily
see that Generic A is not bioequivalent to Generic B; however, both of them
are considered interchangable and could probably be substituted by a
pharmacist.
I think that the mistake is to generalise the word interchangable, all we
can say after a bioequivalence study is that the Generic product XXX is
bioequivalent with the reference product (and eventually interchangable) but
we shouldn=B4t mean that all the generic products are interchangable among
them.
Regards, Silvia
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