Regulatory Requirements for Synthetic Peptide Drugs: China CDE, US FDA and EU EMA Compared

1 Impurity thresholds at a glance

2 The three core documents

Detailed reading: key points of the EMA synthetic peptide guideline.

3 Requirement → data → method

1. Report and identify peptide-related impurities above 0.1%

   CDEFDAEMA

   Data needed

   Related-substance profile, location of known impurities, method specificity

   Typical methods

   RP-HPLC, LC-MS with impurity reference standards

   Quickgene provides

   342 impurity reference standards for semaglutide, tirzepatide and retatrutide, supplied with MS and HPLC data

2. HMW impurities (dimers, aggregates) controlled by type

   EMACDE drug product

   Data needed

   Aggregate type and level, ideally with orthogonal support

   Typical methods

   SEC; analytical ultracentrifugation (SV-AUC) as an orthogonal check

   Quickgene provides

   SV-AUC aggregation and self-association analysis

3. Higher-order structure; generic matches the reference

   CDEEMA

   Data needed

   Secondary and tertiary structure comparison with quantitative similarity

   Typical methods

   Far-/near-UV CD, FTIR, fluorescence, NMR

   Quickgene provides

   Circular dichroism (CD)

4. Orthogonal purity methods by size, charge and hydrophobicity

   EMACDE

   Data needed

   Charge-variant distribution, isoelectric point

   Typical methods

   icIEF, ion-exchange chromatography, capillary electrophoresis

   Quickgene provides

   icIEF pI and charge heterogeneity

5. Cell-based functional assays (when referencing a biological product)

   EMA Section 6

   Data needed

   Receptor activation, relative potency

   Typical methods

   Reporter-gene cell assays

   Quickgene provides

   Cell-based potency testing; CHO-GLP-1 reporter cell line

6. Immunogenicity risk of new or elevated impurities

   FDAEMA Section 6

   Data needed

   Impurity immunogenicity assessment

   Typical methods

   In silico prediction, in vitro T-cell assays

   Quickgene provides

   Custom synthesis of high-purity impurities for immunogenicity testing

4 Frequently asked questions

• All three start at 0.1%—why do they work differently? China and the EU manage every peptide-related impurity with report/identify/qualify thresholds. The 2021 FDA guidance covers generics referencing rDNA-origin products and compares each impurity with the RLD, caps new impurities at 0.5%, and asks for an immunogenicity risk assessment of new impurities between 0.10% and 0.5%.
• Why does ICH Q3A/B not apply directly? Synthetic peptides sit between small molecules and proteins, and ICH Q3A/B, Q6A/B and M7 exclude them fully or partly; the new EMA guideline therefore uses the Ph. Eur. 2034 thresholds instead.
• Which document applies to semaglutide or tirzepatide generics? It depends on the region and the reference product; in the US the relevant product-specific guidance also applies. Confirm the applicable documents with your regulatory team at project start, then design the analytical data package around them.

References