What is GLP (Good Laboratory Practice)?

This blog post isn’t a comprehensive review of GLP regulations. However, there are some key areas of interest that touch pharmacokineticists.

The most important area is the scope of these regulations. Too often, researchers feel compelled to comply with GLP regulations in contexts where they do not apply. This then creates confusion, extra work, and additional costs. Let’s look at the scope of GLPs from the FDA documents and the OECD (italics added for emphasis):

GLP only applies to non-clinical studies and testing. It does not apply to clinical studies. Clinical studies are governed by Good Clinical Practices (GCP), the Declaration of Helsinki, and other regulations intended to protect human participant safety.

Furthermore, much of the GLP structure depends on the roles and responsibilities of the Study Director. This individual is responsible for the oversight and execution of all aspects of the non-clinical study. Study Directors don’t exist in the clinical study arena. Thus, GLP principles cannot be applied to the clinical setting.

Beyond the scope, there are two other items I would like to discuss. First, GLP is a quality management system, not a scientific management system. Or, in other words, GLP defines a set of quality standards for study conduct, data collection, and results reporting.

GLP does not define scientific standards. If a study follows GLP, then you can be reasonably confident that the reported results were collected as outlined in the study protocol. However, this provides no assurances that the study appropriately addresses the scientific hypothesis.

In the world of cooking, GLP would ensure that someone follows the recipe as written. Yet it does not assure you that the recipe was good, or that the resulting item will be tasty!

Second, a key component of the GLP system of quality standards is the Quality Assurance unit (QA). This QA unit is an independent group or individual that monitors the entire study conduct, analysis, and reporting. The purpose of QA is to verify that staff followed all written procedures throughout the study.

As an example, perhaps an SOP says that a senior pharmacokineticist must review the results prior to finalization. The QA auditor will verify that this review occurred. Verification could be done by reviewing a signed document, reviewing an electronic signature, or even speaking with the reviewer. The QA auditor will also ensure that the senior pharmacokineticist has adequate training (as defined by SOPs in the organization) to perform his or her duties.

This quality audit provides confidence that the study staff followed procedures. But again, this audit does not ensure that the procedures themselves are of high quality, or that researchers did not make any errors in the analysis.

1. Using GLP to perform bioanalysis for human clinical trials. As noted in the scope for both GLP and OECD GLP, the principles of GLP only apply to non-clinical studies. Therefore, following GLP, particularly with respect to QA reviews is an unnecessary cost. It is more important to follow analytical validation plans.
2. Performing GLP as a single person. GLP work requires a minimum of 2 or 3 individuals. These are the person performing the work (analyst), a person reviewing the work (management), and a quality assurance reviewer (QA). If SOPs are written well, the analyst and the management can be the same individual. However, QA must always be an independent person.
3. Results of GLP studies are “right.” A statement that a study was conducted in conformance with GLP simply means that quality systems were followed, and that the study’s results accurately report its conduct. It does not indicate that the conclusions drawn are accurate, scientifically robust, or even useful!

I hope you take some time to learn more about GLP and apply it correctly in your future work.