E-drug: Bioequivalence of generics and brand name drugs
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I am the chair of the Drugs and Pharmacotherapy Committee of our provincial
medical association. At a recent meeting one of the other members on the
committee commented that she was finding that she was getting a less than
optimal response when she substituted a generic for a brand name product.
My understanding is that although there have been many anecdotal reports
like this whenever there were formal studies comparing generics and brand
name products the generics were always bioequivalent to the brand name
drug. Is anyone aware of any published studies that contradict this
impression of mine? (I am aware that occasionally there may be reactions
to excipients in generics that are not contained in brand name drugs and
visa versa.)
Joel Lexchin
Joel Lexchin MD
121 Walmer Rd.
Toronto, Ontario
CANADA M5R 2X8
Phone: (416)-964-7186
Fax: (416)-923-9515
e mail: joel.lexchin@utoronto.ca
[Note from moderator: Except for a few drugs for which it has been shown
that the particle size of the active ingredient is important, I think it is
little scientific evidence to support the claim. In countries where drugs
undergo a registration procedure, in vitro bioavailability studies will have
been performed and most often also in-vivo studies. However, I think
sometimes generics are allowed to deviate with up to + - 20% in serum
concentration from the brand name product. Where the control is not so
thorough, or there is no registration procedure for drugs at least
theoretically, you may have products which e.g. do not dissolve and will not
be absorbed. By the way, did she really find that the generic drug gave the
most optimal response? Kirsten Myhr]
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