A specification is the approved list of tests, references to analytical procedures, and acceptance criteria that a drug substance or product must meet to be acceptable for its intended use. Specifications are proposed and justified by the manufacturer and approved by regulatory authorities as conditions of approval; they are one element of the total control strategy.
For each test and limit, provide justification using development data (including clinical/toxicology batches), relevant pharmacopoeial standards, stability data (accelerated and long-term), and demonstrated analytical/manufacturing variability; statistical analyses may be used where appropriate.
CQAs define what must be measured and controlled.
Characterization vs. Release: extensive characterization informs control strategy; a justified subset is used for lot release.
Release vs. Shelf-Life: where justified, tighter release limits and wider shelf-life limits may be set.
Compendial Requirements: apply when relevant (e.g., sterility per USP <71>; bacterial endotoxins calculated per K/M under USP <85>/FDA).