Bioanalytical testing

Out-of-Specification (OOS) is a result obtained in testing raw materials, in-process materials, drug substances, or drug product that fails to meet an expected result of specification.

A specification is a quality standard and includes acceptance criteria that are numerical limits, ranges, or other criteria for the tests described. This criteria establishes standards to which drug substances or drug products should conform to be considered acceptable for its intended use.

If an OOS result occurs, the Food and Drug Administration requires: a valid reason must be determined to invalidate the OOS results (for it to be discarded investigation into the cause of the OOS result must be conducted, and that the results from additional tests should not be averaged unless there is scientifically sound reason that results should be averaged.