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Compound Evidence InstituteEvidence synthesis · established 2023Graded assessments of compounds, trials, methods and supply
Document set current to 30 July 2026
Defined term · Trial design and conduct

Washout

A period between treatments in a crossover design intended to allow the effect of the first to dissipate. A washout shorter than approximately five half-lives leaves carry-over.

Document identifier
CEI-GT-044
Series
Defined term
Version
1.0
Published
30 Jul 2026
Last reviewed
30 Jul 2026
Certainty
Not rated

§1Washout

§1.2Category

Trial design and conduct — Terms describing how a clinical study is constructed and run.

§1.3Related terms

  • Crossover — A design in which each participant receives more than one treatment in sequence, separated by a washout. Efficient for stable conditions and unsuitable where the…
  • Half-life — The time for a plasma concentration to fall by half during the terminal elimination phase. Determines dosing interval, time to steady state and the time required for…
Compound Evidence Institute · CEI-GT-044 · https://compoundevidence.com/glossary/washout/ · retrieved 30 July 2026
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