Before a drug is tested in humans, it is tested in cells and animals. Those studies must be reliable. Good Laboratory Practice is the quality system that governs non-clinical laboratory studies, ensuring that data are accurate, traceable, and reproducible. It covers how studies are planned, how equipment is calibrated, how reagents are stored, how results are recorded, and how archives are maintained. The goal is simple: a regulator should be able to reconstruct exactly what happened in the lab.

GLP was formalized in the 1970s after investigations found widespread problems in toxicology studies submitted to the FDA. The principles were later harmonized internationally by the OECD. A GLP-compliant lab must have standard operating procedures for everything, from cleaning glassware to handling animals. Personnel must be trained and their training documented. Equipment must be calibrated and maintained. Raw data must be recorded promptly and accurately, and any changes must be traceable. The study director is responsible for the overall conduct and for signing the final report.

Key elements:

• Standard operating procedures. Written instructions for every routine task.
• Personnel training. Documented qualifications and training records.
• Equipment calibration. Regular checks to ensure accuracy.
• Raw data integrity. Records made at the time of the experiment, not later.
• Archiving. Data and specimens stored securely for the required period.

GLP applies to safety studies, not to efficacy studies. Clinical trials follow GCP instead.