Voxelotor is a pharmaceutical ingredient whose molecular pharmacology encompasses primary target interactions, off-target binding to safety-relevant proteins, and concentration-response relationships that collectively determine whether pharmacologically-based or NOAEL-based OEL derivation methodology is more protective for occupationally exposed workers. The identification of the critical pharmacodynamic effect and its dose-response threshold in humans—from clinical pharmacology studies or clinical pharmacokinetic-pharmacodynamic modelling—provides a scientifically superior basis for OEL derivation compared to default interspecies extrapolation from animal toxicity data.
PDE derivation for Voxelotor applies the composite uncertainty factor methodology: F1 accounts for interspecies pharmacokinetic and pharmacodynamic differences (default 12 for rat-to-human, refinable with toxicokinetic AUC bridging data), F2 covers intraspecies variability in the human population including sensitive subgroups (default 10), F3 adjus
