Abstract
ICH Q1B defines the standard photostability-testing requirements for drug products, including exposure to at least 1.2 million lux hours of visible light and 200 W·h/m² of near-ultraviolet radiation. Finalized in 1996, the guideline was developed when biologics represented only a small share of approved medicines. Today, biologics account for roughly one-third of new FDA approvals, raising the question of whether Q1B remains fit for purpose for monoclonal antibodies.
This review identifies four major mismatches between the guideline and antibody products: the test exposure is often too harsh, the spectral profile differs from ordinary manufacturing and clinical lighting, indirect photochemical routes through excipients and trace metals are not adequately represented, and conventional endpoints do not capture key antibody liabilities such as aggregation, fragmentation, charge heterogeneity, and loss of Fc receptor binding.
The article reviews the underlying photochemistry of antibody photodegradation, maps light exposure across the product life cycle, examines formulation and packaging mitigation strategies, and proposes a two-track framework that separates forced-degradation hazard identification from testing against realistic product exposure.