E-DRUG: therapeutic equivalence of different dosage forms? (3)
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Dear Robert,
In order to judge on a first glance, one might necessary to consider several additional prime points:
Firstly, are A and B bioequivalent? In case of situation, that there are just X and water, then maybe YES. Are there same concentrations and the same formulations in "A" 100ml and "B" 200ml? If there is any excipient interfering pharmacokinetics of b Ab or b Bb (e.g., with known properties to prolong circulation, act on distribution features), then PK studies should be done in order to show bioequivalence.
Secondly, not all bioequivalent drugs are therapeutically equivalent and vice versa, biological alternatives can be therapeutically equivalent if differences are clinically not relevant (for a particular indication, you are buying this medicine use for).
Bioequivalent drugs can be therapeutical alternatives. E.g., if there is a specific excipient in b Ab or b Bb , that makes safety profile different (e.g., not known excipient with unknown or specific safety profile), then b Ab and b Bb are not therapeutically equivalent.
If method of manufacturing of b Ab and b Bb is different and drugs have had e.g., different by-products, different degradation profile during storage, then safety profile might be different. In this case they might be therapeutically non-equivalent due to safety reasons. The answer might be in files for authorization of b Ab and b Bb , in Drug Authorization Department of your country (Romania).
Thirdly, the issue of therapeutical equivalence is always also very personal. Particular person can be sensitive to specific excipient of product b Ab or b Bb . Then these products will not be therapeutically equivalent. In this case attending physician should be involved into decision about therapeutical equivalence. So, this is behind regulatory competence.
If you do not have established legal provisions for therapeutical equivalence for your country, you could refer to EU definitions. Let me propose you to note some relevant aspects that could be taken from EU guideline b Investigation of Bioavailability and Bioequivalence at http://pharmacos.eudra.org/F2/eudralex/vol-3/home.htm
Best regards,
Romaldas Maciulaitis
Clinical Pharmacologist and Internist
Kaunas Medical University
Lithuania
romaci@takas.lt