Photostability Chamber Illumination Calibration in the Pharmaceutical Industry: UV and Visible Light Control

Photostability testing is essential to assess drug stability under light exposure, as required by ICH Q1B guidelines. Accurate calibration of photostability chambers—controlling both UV and visible light—is critical for reliable, compliant results.

Why Photostability Testing Matters

Light-sensitive drugs can degrade when exposed to UV and visible light, causing:

• Reduced potency

• Toxic impurity formation

• Changes in appearance

• Packaging issues

Regulatory agencies (FDA, EMA) mandate photostability data for product approval.

ICH Q1B Guidelines Overview

• Option 1: ≥1.2 million lux·hours visible light + 200 Wh/m² near UV exposure

• Option 2: Use alternative validated apparatus
  Uniform light distribution and validation are mandatory.

Illumination Calibration Essentials

• Visible Light Calibration: Use lux meters to measure and maintain ≥1.2 million lux·hours; calibrate regularly.

• UV Light Calibration: Measure near-UV irradiance (320–400 nm) ensuring ≥200 Wh/m²; monitor lamp aging.

Importance of Precise Light Control

• Ensures reproducible and valid test results

• Meets regulatory requirements

• Protects product integrity

Poor calibration risks invalid data and delays in development.

Best Practices for Calibration

• Use traceable, calibrated sensors

• Map light distribution in chambers

• Control temperature and humidity

• Keep detailed calibration and maintenance logs

• Train operators thoroughly

Conclusion

Proper photostability testing with well-calibrated UV and visible light exposure is vital for pharmaceutical quality and regulatory compliance. A robust calibration program supports accurate stability data, product safety, and successful market approval.