[e-drug] therapeutic equivalence of different dosage forms? (5)

["Peter Mol" <p.mol@med.rug.nl>]

E-DRUG: therapeutic equivalence of different dosage forms? (5)
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Dear Robert,

In general for parenteral formulations bioequivalence studies do not have to
be performed to substantiate therapeutic equivalence, provided that "the
product is to be administered as an aquaous intravenous solution containing
the same active substance in the same concentration as the currently
authorised product". Because as a rule bioavailability of an intravenously
administered drug is 100%. This also applies to "a formulation intended for
orther parenteral routes, e.g. intramuscular or sc, if the product is of the
same type of solution (oily, aquaous) contains the same concentration of the
same active substance and the same or comparable excipients as the currently
approved medicinal product." Many of the aquaous IV solutions contain very
simple excipients that do not interfere with absorption of the product or
cause specific untoward reactions in specific patient groups as suggested by
Maciulaitis. (A common example of such a problem might be allergic responses
in sensitive populations in case of oral drug formulations where the
excipient e.g. carboxymethyl cellulose is replaced by lactose.) Of course
assuming that the excipients used are safe and have itself no impact on the
efficacy of the product.

This (somewhat) formal answer comes from the Note for Guidance on the
investigation of bioavailability and bioequivalence (CHMP/EWP/QWP/1401/98)
by the European Medicines Agency (EMEA). This is the European Regulatory
Body's guidance for the industry when applying for therapeutic equivalence
of a generic product. You can freely download that from the EMEA website.

So from a (European) regulatory point of view, the products can be
considered therapeutically equivalent when 2 X 100 ml is administered
instead of 1 X 200 ml. But it may be important to take into consideration
the remarks made by Murtade Sesay on the pack-size and guidelines. Of course
reliability of the supplier and quality control of the chain of procurement
are probably other issues you may want to consider (but this is not my field
of expertise.)

With regards,

Peter G.M. Mol
Pharmacist-researcher
Department of Clinical Pharmacology
University Groningen
P.O. Box 196
9700 AD Groningen
tel. +31 50 3638313
fax, +31 50 3632812