Packaging Materials Impact on Pharmaceutical Stability Testing

Introduction

Pharmaceutical packaging materials serve more than a containment role—they are active participants in preserving drug quality, safety, and efficacy. From shielding against moisture, oxygen, and light to ensuring physical protection, packaging materials must be carefully selected and validated to maintain product stability under ICH-recommended conditions. As Stability Studies simulate storage over time, the packaging’s performance becomes a critical determinant of shelf life and regulatory acceptance.

This article examines how packaging materials influence stability study outcomes. We explore different material types, their properties, compatibility with drug substances, regulatory expectations, and strategies for selecting and qualifying packaging materials in the pharmaceutical industry.

Types of Packaging Materials in Pharma

1. Plastics

• HDPE (High-Density Polyethylene): Common for solid oral dosages; good moisture barrier
• LDPE (Low-Density Polyethylene): Flexible; used in tubes and dropper bottles
• PET (Polyethylene Terephthalate): High clarity; used in oral liquids
• PP (Polypropylene): Resistant to heat and chemicals; used in injectable and ophthalmic packaging

2. Glass

• Type I: Borosilicate glass; inert and suitable for injectables
• Type II: Treated soda-lime glass; used for solutions
• Type III: Lower resistance; limited to non-aqueous solutions

3. Foils and Films

• PVC (Polyvinyl Chloride): Basic blister film; low barrier
• PVDC (Polyvinylidene Chloride): High moisture barrier for blister packs
• Aluminum Foil: Total barrier to light, oxygen, and moisture; used in cold-form blisters and sachets

4. Rubber and Elastomers

• Used for stoppers and gaskets; must be inert, non-reactive, and free of extractables

Critical Packaging Material Properties Affecting Stability

1. Moisture Permeability

Moisture ingress is one of the primary causes of degradation in hygroscopic drugs. Packaging must minimize water vapor transmission rate (WVTR), particularly for products stored in ICH Zone IVb (30°C/75% RH).

2. Oxygen Transmission Rate (OTR)

Oxygen-sensitive APIs can oxidize, impacting potency. Oxygen permeability testing is essential when using plastic bottles or films.

3. Light Transmission

Light exposure can degrade photosensitive products. ICH Q1B requires light-protective packaging for susceptible drugs, including amber containers or aluminum foil wraps.

4. Sorption and Leaching

• Sorption: API or excipients adsorb to packaging walls, lowering potency
• Leaching: Packaging components migrate into the product, risking toxicity

5. Thermal Stability

Packaging must withstand thermal cycling without degradation. This is especially relevant during accelerated testing (40°C/75% RH).

Regulatory Expectations for Packaging Materials in Stability

FDA

• 21 CFR 211.94: Containers must not be reactive, additive, or absorptive
• FDA Guidance on Container Closure Systems (1999): Describes testing and documentation expectations

ICH

• ICH Q1A(R2): Stability testing should use the same container-closure system as proposed for marketing
• ICH Q3B/Q3C: Impurities from degradation or leachables must be controlled

WHO

• TRS 961 Annex 9: Stability Studies must reflect real packaging conditions
• Focus on low- and middle-income countries with challenging climates

Material Testing and Validation

Extractables and Leachables Studies (E&L)

These studies identify and quantify potential leachables that can migrate from packaging into the drug product over time.

Testing Approaches

• Use exaggerated conditions (temperature, pH, solvents)
• Techniques: GC-MS, LC-MS, ICP-MS
• Performed for rubber stoppers, plastics, adhesives, inks

Permeation Testing

• Moisture Vapor Transmission Rate (MVTR): For blisters, sachets, bottles
• Oxygen Transmission Rate (OTR): For oxygen-sensitive APIs

Compatibility Studies

• Stress studies to test drug-packaging interactions
• pH stability, degradation profiling, color change monitoring

Packaging Material Qualification and SOPs

Qualification Steps

1. Supplier qualification and COA verification
2. Material ID testing (FTIR, DSC, TGA)
3. Initial extractables study
4. Stability study initiation with final packaging

Essential SOPs

• SOP for Packaging Material Evaluation
• SOP for Extractables and Leachables Testing
• SOP for Packaging Material Specification and Approval
• SOP for Container Closure System Validation

Common Packaging Material-Related Failures

1. Delamination of Foil Blisters

Occurs during high humidity or thermal cycling. Results in compromised barrier properties.

2. Container Crazing or Cracking

Plastic containers may degrade over time or react with solvents.

3. Color Change of Product

Indicates photodegradation due to insufficient light protection.

4. Leachables Above Threshold

Detected during long-term stability; may require a packaging switch or toxicology study.

Case Study: Moisture-Ingress Failure in PVC Blister

A fixed-dose combination tablet exhibited potency drop after 3 months of accelerated stability. Investigation showed high WVTR in standard PVC blisters. PVDC-coated film was substituted, restoring moisture barrier integrity. Retesting confirmed stability, and the new packaging was adopted for global launch.

Packaging Selection Strategy in Stability Programs

1. Start with High-Barrier Materials

Especially for new molecules with unknown sensitivity profiles.

2. Use Marketing-Equivalent Packaging for Registration Batches

Ensures that stability data aligns with what patients will receive.

3. Evaluate Environmental Sensitivity

• Moisture: Use foil or PVDC
• Oxygen: Consider glass or multilayer PET
• Light: Amber glass or UV-resistant plastics

Future Trends in Packaging Materials

• Smart polymers for active barrier response
• Sustainable and biodegradable films
• Digital moisture sensors integrated into packaging
• Automated integrity testing systems

Auditor Expectations

During a GMP Inspection

• Validated packaging specs and test reports
• Supplier change control documentation
• Risk assessment for material substitution
• Consistency between stability samples and marketed presentation

Conclusion

Packaging materials significantly influence pharmaceutical product stability, and their impact must be evaluated thoroughly through compatibility studies, regulatory alignment, and real-time stability testing. By integrating scientifically robust material selection strategies with GMP documentation, pharma companies can ensure product integrity and regulatory compliance across global markets. For SOP templates, test protocols, and packaging qualification checklists, visit Stability Studies.