Good Laboratory Practice (GLP) in Pharmaceutical QC Laboratory: Principles, SOP Guidelines and Best Practices

Good Laboratory Practice (GLP) is an important part of maintaining reliable, consistent and traceable laboratory work. In pharmaceutical quality control (QC), laboratory activities must be properly planned, performed, documented and reviewed so that test results can be trusted.

A good laboratory practice system is not limited to wearing personal protective equipment or following an SOP. It also involves trained personnel, suitable facilities, qualified equipment, controlled documents, appropriate reagents and reference materials, proper records, data integrity and a well-organized quality system.

The World Health Organization (WHO) provides detailed guidance for pharmaceutical quality-control laboratories covering areas such as organization, quality management, documentation, personnel, premises, equipment, reagents, reference substances, calibration, testing, evaluation of results and laboratory safety.

This guide explains the major GLP principles in simple language and provides practical guidance for pharmacy students, QC analysts and pharmaceutical laboratory professionals.

What is Good Laboratory Practice?

Good Laboratory Practice is a quality-focused approach that helps laboratories perform their activities in a consistent, controlled and documented manner.

In pharmaceutical QC, analysts may perform different types of testing, such as assay, dissolution, disintegration, identification, related substances, pH, microbial testing and instrumental analysis. Regardless of the test, the work should be performed according to approved procedures and the resulting data should be properly recorded and reviewed.

For example, when an analyst performs UV analysis, the instrument should be suitable for the intended test and its calibration or performance status should be verified according to the applicable procedure. You can also read our guide on UV spectrophotometer calibration parameters and procedure as per IP for more information.

The main purpose of GLP is to help ensure that laboratory results are accurate, reliable, reproducible and traceable.

Why is GLP important in pharmaceutical QC?

Quality control laboratories generate analytical data that may be used to assess the quality of pharmaceutical products. Therefore, laboratory errors can affect important quality decisions.

A properly implemented GLP system helps laboratories:

• Reduce avoidable analytical errors
• Maintain consistent laboratory practices
• Protect the integrity of samples and data
• Improve traceability
• Maintain equipment in suitable condition
• Control reagents and reference materials
• Ensure personnel are properly trained
• Support investigation of unexpected results
• Improve laboratory safety
• Demonstrate compliance with applicable quality requirements

WHO's pharmaceutical QC laboratory guidance is designed to support reliable testing of medicines and includes requirements covering both technical activities and the laboratory quality system.

GLP is particularly important in pharmaceutical laboratories because laboratory results can contribute to decisions about whether a material or pharmaceutical product meets its specified requirements.

Important GLP practices in a pharmaceutical laboratory

Follow current and approved SOPs

Laboratory activities should be performed according to current, approved Standard Operating Procedures (SOPs).

Examples include SOPs for:

• HPLC operation
• UV-Visible spectrophotometer operation
• Dissolution testing
• Analytical balance operation
• pH meter operation
• Preparation of reagents
• Preparation of standard solutions
• Cleaning of laboratory equipment
• Handling of reference standards
• Sample management

Analysts should use the current approved version of an SOP. If a procedure appears incorrect or requires improvement, the issue should be reported through the laboratory's document-control system rather than changing the procedure independently.

Trained laboratory personnel

Personnel should have appropriate education, training and experience for the activities they perform.

Training may cover:

• Analytical procedures
• Instrument operation
• Laboratory safety
• Good documentation practices
• Data integrity
• Chemical handling
• Sample handling
• SOP requirements
• Deviation and investigation procedures

Training should be documented, and personnel performing specialized activities should be appropriately assessed for competency.

WHO guidance specifically emphasizes having sufficient personnel with appropriate education, training, technical knowledge and experience for their assigned laboratory functions.

Proper documentation

Documentation is one of the most important parts of good laboratory practice.

Laboratory records may include:

• Sample receipt records
• Sample preparation records
• Standard preparation records
• Reagent preparation records
• Instrument usage records
• Raw analytical data
• Calculations
• Equipment calibration records
• Maintenance records
• Environmental records where applicable
• Deviations
• Investigations
• Analytical reports

A laboratory should be able to trace a reported result back to the original information and activities used to generate that result.

Good documentation practices

Important laboratory information should be recorded at the time the activity is performed, following the approved documentation procedure.

Good practices include:

• Use approved forms and formats.
• Record information contemporaneously.
• Clearly identify the person performing the activity.
• Record dates and relevant times where required.
• Maintain original data.
• Correct errors according to the approved procedure.
• Do not conceal or delete unexpected results.
• Maintain appropriate traceability for electronic records.

For electronic laboratory systems, access controls, audit trails, backups and other data-integrity controls should be implemented according to applicable requirements.

WHO guidance includes specific expectations for protecting the integrity and confidentiality of laboratory data and controlling electronic information.

Equipment, calibration and maintenance

Laboratory instruments should be suitable for their intended use and maintained in an appropriate operating condition.

Common equipment in pharmaceutical QC laboratories includes:

• Analytical balances
• pH meters
• UV-Visible spectrophotometers
• HPLC systems
• FTIR instruments
• Dissolution apparatus
• Disintegration testers
• Friability testers
• Stability chambers
• Conductivity meters

Before using an instrument, the analyst should check its identification, calibration or qualification status, maintenance status and cleanliness, as applicable.

For HPLC analysis, for example, instrument performance and calibration requirements should be controlled according to the applicable procedure. Our guide on HPLC calibration parameters and procedures as per IP provides more detail on this topic.

Similarly, dissolution testing requires appropriate control of apparatus parameters. You can read Dissolution Apparatus Calibration: Key Parameters and Procedures for a more detailed discussion.

If an instrument is damaged or suspected of malfunctioning, it should be handled according to the laboratory's equipment and deviation procedures. It should not simply be used for routine testing without appropriate assessment.

Reagents, reference standards and sample handling

Reagents and chemicals should be correctly identified, appropriately stored and used according to their intended purpose.

A reagent label may include information such as:

• Name
• Concentration or strength where applicable
• Preparation date
• Expiry or retest information where applicable
• Storage condition
• Prepared by
• Identification or status

The exact information required depends on the reagent and the laboratory's approved procedure.

Reference standards and working standards also require appropriate identification, storage, handling and traceability. They should be used according to the relevant analytical procedure and applicable quality requirements.

Sample handling

Samples should be properly identified and protected against contamination, deterioration and mix-up.

Important controls include:

• Correct sample identification
• Proper storage
• Appropriate sample preparation
• Controlled handling
• Traceable records
• Use of approved analytical procedures

Sample preparation can have a significant effect on analytical results, so every step should be performed carefully and documented appropriately.

Laboratory safety and chemical handling

Safety is an essential part of good laboratory practice.

Depending on the activity, appropriate personal protective equipment may include:

• Laboratory coat
• Safety glasses or goggles
• Gloves
• Face protection
• Other suitable protective equipment based on the risk assessment

Chemicals should be handled according to their hazards, safety information and laboratory SOPs.

When working with concentrated acids, analysts should follow the approved chemical-handling procedure and appropriate precautions. A commonly taught laboratory safety principle is to add acid slowly to water rather than adding water directly to concentrated acid.

Chemical spills should be dealt with immediately using the appropriate spill-response procedure.

Flammable, toxic and otherwise hazardous chemicals should be stored in designated areas with appropriate controls.

Laboratory waste should also be segregated and disposed of according to the type of waste and applicable safety requirements.

Data integrity in pharmaceutical QC

Data integrity has become an essential part of pharmaceutical laboratory quality systems.

Laboratory data should be trustworthy and traceable throughout its lifecycle.

A commonly used framework is ALCOA, referring to data that are:

• Attributable
• Legible
• Contemporaneous
• Original
• Accurate

Additional expectations are often described under the term ALCOA+, which extends these principles to include characteristics such as completeness, consistency, enduring records and availability.

Examples of poor data practices include:

• Recording results much later from memory
• Sharing individual electronic-system passwords
• Deleting unexpected analytical results
• Performing undocumented testing
• Changing data without appropriate traceability
• Using uncontrolled calculation spreadsheets

A strong data-integrity system helps ensure that laboratory records accurately represent what actually happened during testing.

What happens when an unexpected result occurs?

An unexpected result should not simply be ignored or repeatedly tested until a satisfactory result is obtained.

The laboratory should follow its approved investigation procedure.

Depending on the situation, an investigation may consider:

• Sample preparation
• Calculation
• Instrument performance
• Reagents
• Reference standards
• Analytical procedure
• Equipment condition
• Analyst technique
• Environmental conditions
• Previous relevant results

The appropriate investigation process depends on the applicable quality system and regulatory requirements.

GLP and tablet quality control

Good laboratory practices are also important when performing routine quality-control testing of tablets.

Tests may include:

• Appearance
• Weight variation
• Hardness
• Friability
• Disintegration
• Dissolution
• Assay
• Content uniformity
• Other tests specified by the applicable product specification or pharmacopoeia

For a detailed overview, see our article on quality control tests of tablets in the pharmaceutical industry.

The important point is that the analyst should not only obtain a result but should also ensure that the test was performed using appropriate equipment, materials, procedures and documentation.

GLP vs GMP

GLP and GMP are closely related but are not identical.

Good Laboratory Practice focuses mainly on the organization, control and reliability of laboratory activities and data.

Good Manufacturing Practice (GMP) covers the broader pharmaceutical manufacturing and quality system, including production, facilities, personnel, equipment, documentation, quality control and other areas.

A pharmaceutical QC laboratory may therefore operate within a broader GMP environment while applying appropriate good laboratory practices to its analytical work.

WHO's pharmaceutical quality-assurance publications cover both pharmaceutical quality-control practices and GMP requirements.

Practical GLP checklist for QC analysts

Before starting an analytical activity, an analyst can consider the following:

• Is the current approved SOP being used?
• Am I trained and authorized to perform this activity?
• Is the sample correctly identified?
• Is the equipment suitable and within its required status?
• Are the reagents suitable for use?
• Are reference standards properly identified and stored?
• Are calculations and preparations being documented?
• Is the laboratory area suitable for the activity?
• Am I following the required safety precautions?
• Am I recording data at the time of the activity?
• Can the complete analytical process be reconstructed from the records?

This simple checklist can help analysts develop good laboratory habits, although it should not replace the laboratory's approved procedures.

Common GLP mistakes to avoid

Some common laboratory practices can compromise the quality or traceability of analytical work.

Using outdated SOPs

Always confirm that the current approved procedure is being used.

Using equipment with uncertain status

Check the relevant calibration, qualification and maintenance status before use.

Poor sample labeling

Incorrect or incomplete labeling can result in sample mix-ups.

Recording data later

Important laboratory information should be recorded when the activity is performed according to the applicable documentation procedure.

Ignoring unexpected results

Unexpected or potentially invalid results should be handled through the appropriate laboratory investigation process.

Poor reagent control

Reagents should be properly identified, stored and controlled.

Sharing electronic credentials

Individual user accounts should be used according to the laboratory's access-control requirements.

Frequently asked questions

What is GLP in pharmaceutical quality control?

GLP is a systematic approach to laboratory work that helps ensure analytical activities are performed consistently, appropriately documented and capable of producing reliable and traceable results.

Why is GLP important in QC laboratories?

GLP helps control laboratory activities, reduce avoidable errors, protect data integrity and improve the reliability of analytical results.

Is GLP the same as GMP?

No. GLP focuses primarily on laboratory practices, while GMP is a broader quality system covering pharmaceutical manufacturing and related quality activities.

What are the major elements of GLP?

Important elements include trained personnel, approved procedures, documentation, equipment, calibration, reagents, reference standards, sample handling, data integrity, testing and laboratory safety.

Is calibration part of GLP?

Calibration and equipment control are important parts of maintaining a suitable pharmaceutical QC laboratory. The specific calibration requirements depend on the equipment, its intended use and applicable procedures.

Conclusion

Good Laboratory Practice is much more than a collection of laboratory rules. It is a systematic way of organizing laboratory activities so that testing is performed consistently, data remain reliable and results can be traced back to the work that generated them.

In a pharmaceutical QC laboratory, important GLP areas include trained personnel, SOPs, documentation, equipment control, calibration, reagents, reference standards, sample handling, data integrity, safety and proper investigation of unexpected results.

The WHO's revised 2024 guidance for pharmaceutical quality-control laboratories provides detailed recommendations covering these areas and is an important reference for laboratories working within pharmaceutical quality systems.

For pharmacy students and QC professionals, understanding GLP is useful not only for laboratory work but also for pharmaceutical QC interviews and understanding how quality systems operate in the pharmaceutical industry.

References

1. World Health Organization. WHO Good Practices for Pharmaceutical Quality Control Laboratories, WHO Technical Report Series No. 1052, Annex 4, 2024.
2. World Health Organization. Quality Assurance of Pharmaceuticals: A Compendium of Guidelines and Related Materials, 10th Edition, Volume 1, 2024.
3. World Health Organization. Quality Assurance of Pharmaceuticals: A Compendium of Guidelines and Related Materials, Volume 2: Good Manufacturing Practices and Inspection, 10th Edition, 2024.
4. World Health Organization. Training on Good Laboratory Practice to pharmaceutical manufacturers in Nepal, 2024.

Disclaimer: This article is provided for educational purposes. Laboratory procedures, safety requirements, acceptance criteria and regulatory expectations should always be verified against the current applicable pharmacopoeia, regulatory guidance and your organization's approved SOPs.