Replacing a USP method with a house method

[Albany-12303]

We have a house method for an assay that we want to use instead of the compendial USP method (the house method does both Assay and impurities - so we can kill 2 birds with the same stone. Also, the USP method has much more tailing)

If we were to drop the USP method, is an equivalency study required? It seems to me that if the house method has been validated and passes the validation criteria, it should be considered equivalent automatically.

If we need to do the equivalacy (comparison) study withthe USP method I think that we would need to also validate the USP method beforehand - since this is for a drug product. My understanding is that USP methods for drug products (but not API methods) need to be validated.

Doing the equiv study may be quite a hassle

[gbalock]

MD Guy
We typically do an equivalency if we wish to use a in house method over the USP method. The criteria and protocol that we use is very similar to what we would use for intermediate precision. The one thing to keep in mind is that the FDA is going to use the USP method when evaluating your product, so make sure that your product meets the USP specs.

[Alfred88]

Dear:

We have got some in-house methods that are not derived from USP. We did the validation according to USP<1225> and ICH Q2A & Q2B.

USP does not have assay for all materials, and even if it does, that USP method works for that material alone (pure) but not in a complex matrix (there are exceptions). For HPLC assay, we try (if available) USP method as a starting point, but may not use it, if that method failed the system suit requirements or specificity (co-elution).

Alfred.