Lexicon · NucLex for innovators
Biodistribution
Fully specified name: Biodistribution (concept)
The distribution of a substance across biological compartments over time.
- Scope note
- Include time, measurement basis, biological setting, and uncertainty.
- Synonyms
- None recorded as true synonyms in this context.
- Monograph
- Biodistribution and pharmacokinetics (planned; brief only)
- External mappings
- None recorded. In W0 no mapping to SNOMED CT® or any external authority is asserted for this entry. A future mapping record will carry source system, identifier, version, relation type, evidence, author, confidence where meaningful, and review state.
- Formal status
- Editorial entry only. It is not part of any released ontology and a prose edit here changes no formal definition.
Draft. This entry is an unreviewed draft. Its sources have not been checked by a named person and no domain reviewer has approved it. Treat every claim as provisional.
Notes
Biodistribution describes where a substance is in the body, how much is in each place, and how that changes with time after administration. For a radiopharmaceutical the substance can be followed by its radiation, which is what makes imaging and counting possible. The compartments may be whole organs, tumors, blood, excreta, or finer divisions such as tissue regions or cell populations.
Three qualifications travel with every biodistribution statement. The time: a snapshot at one hour and one at three days describe different things, and a full account is a time series. The measurement basis: data may come from dissected tissue in animals, from imaging in people, or from blood and urine sampling, each with its own units, corrections, and sources of error. The biological setting: species, disease state, prior treatment, and organ function all change the result, so a preclinical distribution is not a human distribution and one patient's is not another's.
Pharmacologists use "biodistribution" chiefly for preclinical tissue studies, and "pharmacokinetics" for the time course of concentration in accessible fluids. Nuclear medicine physicians and physicists use biodistribution for the organ-level data that feed dose estimates. The concepts overlap without coinciding. NucLex records a biodistribution as a set of compartment, quantity, time, and method observations with their uncertainty, and keeps the model fitted to those observations as a separate record.