SOPs are not static documents, but need to be periodically reviewed and revised to reflect practices followed and /or changes in regulatory requirements. It is important to maintain a historical file of SOPs. This file should contain the old versions of the SOPs that were made obsolete when an SOP was revised and a new version released for use. This collection of obsolete SOPs helps to show-case the improvements in processes introduced over time and also link raw data /records generated to a particular version of an SOP. At any given time, only the current effective version of any SOP should be in circulation. Hence, it is imperative that while distributing a revised SOP, the old version should be simultaneously retrieved and destroyed. Deviations to SOPs should be documented and the impact or lack thereof on data assessed and documented.
SOPs should be available for at least, but not limited to, the following categories: Test /Reference Items; Apparatus, Materials and Reagents; Record Keeping, Reporting, Storage and Retrieval; Test Systems and Quality Assurance Procedures.
Although it seems like a tedious process to establish, maintain and follow SOPs, it is well worth the effort as it ensures uniformity and hence quality of data. This also aids in building confidence in the data generated at a facility which operates following SOPs.
Reference:
OECD Series on Principles of Good Laboratory Practice and Compliance Monitoring; Document No. 1, OECD Principles of GLP
