Bioequivalence and Bioavailability Forum

Dear Nguyen,

for the ASEAN States following guideline applies:
http://www.bpfk.gov.my/pdfworddownload/drug/ASEAN%20GUIDELINES%20FOR.pdf

It states:
2.5 Essentially similar products
[...] An 'innovator' product is a medicinal product authorised and marketed on the basis of a full dossier i.e. including chemical, biological, pharmaceutical, pharmacological-toxicological and clinical data. A 'Reference Product' must be an 'innovator' product. (see 3.5).
3.5 Reference and test product
Test products in an application for a generic product are normally compared with the corresponding dosage form of an innovator (see 2.5) medicinal product (reference product). The choice of reference product should be justified by the applicant and agreed upon by the regulatory authority.
If the innovator product is not available, an alternative comparator product approved by drug regulatory authority of the country can be used.
The test products used in the biostudy must be prepared in accordance with GMP-regulations. Batch control results of the test product should be reported.

Therefore you should contact the respective authorities beforehand to settle an agreement about the acceptance of your chosen reference product.
Problematic may be the acceptance of the GMP-standard (e.g., Australia accepts only the reference product marketed in Australia, the European Union accepts only European references and products from countries where a 'Mutual Recognition Agreement' exists: Switzerland-yes, USA-no...).

I don't think it will be possible to get an approval from US-FDA, since no reference listed drug product exists for cefixime...
http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm?fuseaction=Search.Overview&DrugName=SUPRAX

Another case is gatifloxacin, where the reference is still marketed:
http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm?fuseaction=Search.Overview&DrugName=TEQUIN
If you have performed your study with this reference, and it was withdrawn from the US market later, safety and efficacy data is still available for FDA's review staff.