Susceptibledose

Susceptibledose is a term used in pharmacology and toxicology to describe the dose of a substance required to produce a predefined effect in individuals or populations identified as more vulnerable to that effect. It emphasizes the lower end of the dose-response distribution by focusing on susceptible subgroups rather than the average response of a general population.

Definition and scope

The concept is endpoint-specific and depends on how susceptibility is defined, which may include genetic factors, age, sex, disease state, organ function, or prior exposure to related chemicals. The susceptible dose is not a fixed value for all individuals but the dose at which a chosen proportion of the susceptible group exhibits the specified outcome. In practice, researchers may express susceptibility with metrics such as a susceptible-ed50 or a similar percentile-based endpoint, derived from dose-response data constrained to the susceptible population.

Determination and data needs

Deriving a suscepible dose requires stratified dose-response data or robust statistical models that account for varying vulnerability within a population. Data can come from clinical trials, observational studies, animal models, or in vitro systems mapped to human-relevant endpoints. The resulting value depends on the chosen endpoint (toxicity, pharmacodynamic effect, immunological response), route of exposure, and exposure duration.

Applications and limitations

Susceptibledose is used to inform risk assessment, regulatory decisions, and comparative toxicology by highlighting risks to more vulnerable groups. Limitations include the scarcity of clearly defined susceptibility criteria, ethical and practical constraints in exposing vulnerable populations, and variability in endpoint definitions. It remains a supplemental concept rather than a universally adopted metric in most regulatory frameworks.

See also

ED50, NOAEL, LOAEL, dose-response, pharmacogenomics.