For manufacturers of biologics and biosimilars, the release of each product batch is contingent on demonstrating that the drug retains its intended biological activity.

Unlike small-molecule pharmaceuticals, for which chemical identity and purity can be confirmed by physicochemical methods, biologics derive their therapeutic effect from complex molecular interactions that these methods cannot fully capture.
Hilary Pollard, Senior Product Manager, Cell Based Assays and Proteomics at Promega UK, investigates.
Potency testing — the quantitative measurement of biological activity relative to a reference standard — is therefore a mandatory component of the lot release package.
Regulatory expectations on both sides of the Atlantic are unambiguous.
ICH Q6B, adopted by the US FDA, EMA and MHRA, reflects the expectation that potency assays measure biologically relevant activity linked to the product's mode of action and correlate with the clinical response (whenever scientifically justified).