What Is Good Laboratory Practice (GLP)?
Good Laboratory Practice (GLP) is a quality system of management controls for research laboratories and organizations to ensure the uniformity, consistency, reliability, reproducibility, quality, and integrity of nonclinical safety studies. GLP regulations were established to ensure that data submitted to regulatory agencies can be relied upon to make critical decisions about drug safety.
In the United States, GLP regulations are codified in 21 CFR Part 58 and enforced by the FDA. Similar regulations exist internationally, including OECD Principles of Good Laboratory Practice, which have been adopted by member countries to facilitate mutual acceptance of data.
GLP requirements encompass multiple aspects of laboratory operations including organization and personnel qualifications, facilities and equipment, testing facility operations, test and control article characterization, protocols and conduct of studies, records and reports, and quality assurance oversight.
Why GLP Compliance Matters
GLP compliance is not optional for studies intended to support regulatory submissions. The consequences of non-compliance can be severe and far-reaching:
Regulatory Rejection
Studies conducted without proper GLP compliance may be rejected by regulatory agencies, requiring sponsors to repeat studies at significant cost and delay. FDA inspectors routinely audit facilities and can issue warning letters, refuse to accept data, or even refer cases for criminal prosecution in cases of fraud.
Data Integrity
GLP requirements ensure that raw data is captured accurately, stored properly, and can be reconstructed if needed. This protects both the sponsor's investment and ultimately patient safety by ensuring decisions are based on reliable information.
International Acceptance
Studies conducted under OECD GLP principles are accepted by regulatory agencies in all OECD member countries, facilitating global drug development programs without the need to repeat studies for different markets.
Types of GLP Toxicology Studies
A comprehensive IND-enabling toxicology program typically includes several types of studies, each designed to evaluate different aspects of drug safety:
Acute Toxicity
Single-dose studies to determine the maximum tolerated dose (MTD) and identify target organs of toxicity. Typically conducted in two species.
Duration: Single dose with 14-day observationRepeat-Dose Toxicity
Multiple-dose studies ranging from 2 weeks to 9 months depending on intended clinical duration. Establishes NOAEL and characterizes toxicity profile.
Duration: 2 weeks to 9 monthsGenetic Toxicology
Battery of in vitro and in vivo tests to assess mutagenic and clastogenic potential. Includes bacterial reverse mutation (Ames), chromosomal aberration, and micronucleus assays.
Duration: 2-4 weeks per assaySafety Pharmacology
Core battery studies evaluating effects on cardiovascular (hERG, telemetry), respiratory, and central nervous systems.
Duration: 1-4 weeks per studyImmunotoxicology
Assessment of immunosuppressive or immunostimulatory potential, particularly important for biologics and immunomodulatory drugs.
Duration: Varies by approachReproductive Toxicity
Fertility, embryo-fetal development, and pre/postnatal development studies. Timing depends on patient population and clinical indication.
Duration: 2-6 months per segmentIND Toxicology Requirements
The FDA and ICH guidelines specify minimum toxicology requirements for IND submission. The exact requirements depend on the intended clinical trial design:
For First-in-Human Single-Dose Studies
For Repeat-Dose Clinical Trials
The duration of repeat-dose toxicity studies must equal or exceed the intended clinical dosing duration, following ICH M3(R2) guidelines:
| Clinical Trial Duration | Rodent Study Duration | Non-Rodent Study Duration |
|---|---|---|
| Single dose | 2 weeks | 2 weeks |
| Up to 2 weeks | 2 weeks | 2 weeks |
| Up to 1 month | 1 month | 1 month |
| Up to 3 months | 3 months | 3 months |
| Up to 6 months | 6 months | 6 months |
| More than 6 months | 6 months | 9 months |
Species Selection Considerations
Selecting appropriate animal species for toxicology studies is a scientific decision that should be based on multiple factors:
Pharmacological Relevance
The species should express the target receptor or enzyme and demonstrate a pharmacological response to the test article. For biologics, this often requires using non-human primates when the molecule doesn't cross-react with rodent targets.
ADME Similarity
Species with similar absorption, distribution, metabolism, and excretion profiles to humans provide more translatable safety data. Metabolic profiling early in development helps inform species selection.
Historical Database
Using species with extensive historical control data allows better interpretation of findings. Unusual species may be scientifically justified but can complicate data interpretation.
Common Species Used
For small molecules, rats and dogs are the most common rodent and non-rodent species. For biologics targeting human-specific epitopes, cynomolgus monkeys are frequently used as the non-rodent species. Minipigs are increasingly used as an alternative non-rodent species for certain programs.
Choosing a GLP Toxicology CRO
Selecting the right CRO partner for your GLP toxicology program is critical. Key evaluation criteria include:
Review the facility's FDA inspection history and any warning letters. A clean inspection record indicates robust quality systems.
Confirm the CRO has experience with your required species and maintains appropriate housing, husbandry, and veterinary care.
Specialized routes like intrathecal, intravitreal, or inhalation require specific expertise and equipment. Ensure the CRO has demonstrated capability.
Board-certified veterinary pathologists with experience in pharmaceutical toxicology are essential for accurate interpretation of findings.
Integrated bioanalytical support for toxicokinetic sampling improves efficiency and data quality compared to shipping samples externally.
Confirm the CRO can accommodate your timeline and has contingency plans for unexpected capacity constraints.
Common Pitfalls to Avoid
Based on regulatory feedback and industry experience, several common issues can derail GLP toxicology programs:
Inadequate Test Article Characterization
GLP regulations require complete characterization of the test article including identity, purity, stability, and homogeneity in dosing formulations. Gaps in this data can invalidate otherwise well-conducted studies.
Protocol Deviations
While deviations are sometimes unavoidable, frequent or significant deviations raise questions about study conduct. Ensure protocols are realistic and that staff are properly trained before study initiation.
Insufficient Recovery Groups
Recovery (reversibility) assessments help characterize whether toxic effects resolve after dosing stops. Inadequate recovery group size or duration can leave important questions unanswered.
Premature IND Submission
Submitting an IND before toxicology studies are complete or final reports are available creates risk. Plan timelines to allow for report finalization and review before submission.