Spectral Transmission Measurements of Pharmaceutical Packaging

Importance of the Topic

Pharmaceutical packaging must protect light-sensitive drug products from photodegradation during manufacturing, storage, and distribution. International compendial standards (EP <3.2.1>, USP <660>, USP <661.2>) mandate testing of light-resistance through spectral transmission measurements. Reliable quantification of transmitted UV-visible light is critical for ensuring product stability, efficacy, and regulatory compliance.

Study Objectives and Overview

This study aimed to evaluate the spectral transmission characteristics of one glass and two plastic pharmaceutical containers used for oral formulations. The goal was to demonstrate compliance with the maximum 10% transmission acceptance criterion over the 290–450 nm range, as specified in EP <3.2.1>, USP <660>, and USP <661.2>.

Materials and Methodology

Three packaging systems were selected:

• Sample 1: Amber, translucent glass vial for oral liquid
• Sample 2: Yellow, opaque plastic container for tablets
• Sample 3: Amber, translucent plastic container for tablets

Sections of each container wall, representing average thickness, were cut, cleaned (soap and water), dried, and wiped with lens tissue. Samples were mounted on the diffuse reflectance accessory (DRA) transmission port using a 6 mm aperture reducer and PTFE clips to eliminate gaps and ensure full coverage.

Instrumentation

The measurements were performed on an Agilent Cary 60 UV-Vis spectrophotometer equipped with an integrating sphere diffuse reflectance accessory and controlled by Cary WinUV software.

Results and Discussion

Spectral transmission scans from 290 to 450 nm showed that all samples remained below the 10% transmission threshold:

• Sample 1 (glass): maximum %T = 1.121%
• Sample 2 (plastic, opaque): maximum %T = 0.155%
• Sample 3 (plastic, translucent): maximum %T = 9.570%

These results confirm that the tested containers meet the compendial light-resistance requirements. Sample 3’s value, close to the limit, highlights the importance of using an integrating sphere accessory to capture scattered light accurately.

Benefits and Practical Applications

• Ensures packaging compliance with regulatory standards for light-sensitive pharmaceuticals
• Provides a robust QA/QC method for differentiating container materials and colors
• Facilitates rapid, reproducible testing using plug-and-play accessory setup

Future Trends and Opportunities

Advances may include miniaturized integrating spheres for benchtop spectrophotometers, automated sample handling, and expanded application to multilayer or coated packaging. Integration with LIMS and regulatory data management systems will streamline compliance workflows.

Conclusion

The Agilent Cary 60 UV-Vis spectrophotometer with diffuse reflectance accessory delivers accurate, reproducible spectral transmission measurements for glass and plastic pharmaceutical containers. All tested samples complied with EP <3.2.1>, USP <660>, and USP <661.2> light-resistance criteria, demonstrating the method’s suitability for regulatory quality assurance.

References

1. Kowalska J.; Rok J.; Rzepka Z.; Wrześniok D. Drug-Induced Photosensitivity–From Light and Chemistry to Biological Reactions and Clinical Symptoms. Pharmaceuticals (Basel) 2021, 14(8), 723. DOI:10.3390/ph14080723
2. Ph. Eur. Chapter 3.2.1 Glass Containers for Pharmaceutical Use. Council of Europe; 2019.
3. USP 40–NF 35, General Chapter <660> Containers – Glass. United States Pharmacopeial Convention.
4. USP 42–NF 37, General Chapter <661.2> Plastic Packaging Systems for Pharmaceutical Use. United States Pharmacopeial Convention.