Equivalence testing checks whether a technical from a new source is chemically similar enough to an approved reference source that the reference's safety data still applies. If it is, the new source can usually be registered without repeating the full toxicology package.
The comparison rests mainly on purity and impurities. A generic maker's route may differ from the originator's, and a different route can leave different impurities. Equivalence testing asks whether those differences matter.
How the assessment works
Most regulators follow an approach set out by FAO and WHO and in similar EU guidance. It works in tiers.
- Tier 1 compares the new source's specification and five-batch analysis with the reference specification and profile.
- If Tier 1 shows differences that could matter, Tier 2 asks for toxicology data, often acute studies or mutagenicity tests, to show the differences do not raise the hazard.
- If the data still shows a higher hazard, the new source is not equivalent and needs its own full data package.
The usual Tier 1 tests
Under the FAO and WHO approach, a new source is generally treated as equivalent at Tier 1 when all of these hold. Your regulator may apply its own version, so check its guidance.
- The minimum purity is not lower than the reference minimum.
- No non-relevant impurity exceeds the reference maximum by more than 50% of that level, or by 3 g/kg, whichever is greater.
- No toxicologically relevant impurity exceeds the reference maximum.
- No new impurity appears at 1 g/kg or more, and no new relevant impurity appears at all.
What you need from the supplier
The assessment depends on good chemistry data. You will need a five-batch analysis, explained in what a five-batch analysis is, a proposed specification and validated methods. If Tier 2 is needed, you also need GLP studies on the supplier's own material.
The process description and impurity data are confidential, so the supplier often sends them directly to the regulator. Agree this route in advance, and agree who answers the regulator's questions.
Check which reference profile your regulator uses before you start. In some countries it is the profile of the first approved source. In others it is a published FAO specification or a regional reference. A source that is equivalent in one country may not be in another.
Equivalence also matters for formulations. Some regulators compare the formulated product with a reference product as well, using physical tests and sometimes acute toxicity. Ask your regulator whether this applies.
Keeping equivalence after approval
Equivalence is granted for a profile, not for a company name. If the supplier changes its route, its key raw materials or its site, the profile can change and equivalence may need to be shown again. Write a change-notification clause into your supply contract, and test incoming lots for the key impurities, not just purity.
Next step
We check a supplier's batch data against the reference profile your regulator uses and have lots tested for the impurities that matter. Book a free sourcing review to assess a source.