This guidance for industry provides the Agency’s current thinking on how to evaluate out-ofspecification (OOS) test results. For purposes of this document, the term OOS results includes all test results that fall outside the specifications or acceptance criteria established in drug applications, drug master files (DMFs), official compendia, or by the manufacturer. The term also applies to all in-process laboratory tests that are outside of established specifications.

This guidance applies to chemistry-based laboratory testing of drugs regulated by CDER. It is directed toward traditional drug testing and release methods. These laboratory tests are performed on active pharmaceutical ingredients, excipients and other components, in-process materials, and finished drug products to the extent that current good manufacturing practice (CGMP) regulations (21 CFR parts 210 and 211) and the Federal Food, Drug, and Cosmetic Act (the Act) (section 501(a)(2)(B)) apply. The principles in this guidance also apply to in-house testing of drug product components that are purchased by a firm. This guidance can also be used by contract firms performing production and/or laboratory testing responsibilities.

Specifically, the guidance discusses how to investigate OOS test results, including the responsibilities of laboratory personnel, the laboratory phase of the investigation, additional testing that may be necessary, when to expand the investigation outside the laboratory, and the final evaluation of all test results.

The Agency, in accordance with its August 2002 “Pharmaceutical CGMPs for the 21st Century” initiative, encourages modern approaches to manufacturing, monitoring, and control to enhance process predictability and efficiency. Process Analytical Technology (PAT) takes a different approach to quality assurance by using process controls and in-process data as the release specification instead of relying on single laboratory determinations to make batch acceptability decisions.

This guidance is not intended to address PAT approaches, as routine in-process use of these methods might include other considerations. For information on timely in-process testing, see the CGMP guidance entitled PAT — A Framework for Innovative Pharmaceutical Development, Manufacturing, and Quality Assurance (September 2004).

The contents of this document do not have the force and effect of law and are not meant to bind the public in any way, unless specifically incorporated into a contract. This document is intended only to provide clarity to the public regarding existing requirements under the law. FDA guidance documents, including this guidance, should be viewed only as recommendations, unless specific regulatory or statutory requirements are cited. The use of the word should in Agency guidance means that something is suggested or recommended, but not required.