Climatic Chamber Configurator
Discover the Climatic Chamber Configurator
Our guide to choosing the climate chamber best suited to your needs.
The ICH Q1B standard defines the procedures for photostability testing of active pharmaceutical ingredients and finished pharmaceutical products. Published by the International Council for Harmonization (ICH), this guideline establishes the light exposure conditions, types of lamps, and acceptance criteria that each drug must pass before being placed on the market. The tests are conducted in a photostability chamber , which exposes the samples to the doses of visible and UV light specified in the guideline.
In this guide we analyze the requirements of ICH Q1B, the test conditions, the relationship with ICH Q1A (stability testing) , and the FDM chambers designed to perform these tests.
What is photostability and why is it important?
Photostability is the ability of an active ingredient or pharmaceutical product to maintain its properties unchanged when exposed to light. Exposure to sunlight and artificial light can cause:
- Degradation of the active ingredient: reduction of therapeutic potency
- Formation of degradation products: potentially toxic
- Alteration of physical characteristics: change in color, consistency, pH
The ICH Q1B photostability test is de facto mandatory for the registration of new drugs with the EMA (Europe) and the FDA (United States). Without photostability data, the registration dossier is incomplete.
ICH Q1B requirements: exposure conditions
ICH Q1B prescribes two exposure conditions that must be achieved during the test:
| Parameter | Requirement | Note |
|---|---|---|
| Visible light | Not less than 1.2 million lux hours | Measured with a calibrated luxmeter |
| UV radiation | Not less than 200 W h/m2 (range 320-400 nm) | Near-UV, measured with radiometer |
Exposure can be performed simultaneously (visible + UV light together) or sequentially (first UV, then visible or vice versa).
Lamp options provided by the standard
The ICH Q1B provides two options for the light source:
- Option 1: Lamp that simulates full sunlight (e.g. xenon lamps with filters, metal discharge lamps with filters)
- Option 2: Combination of cool white fluorescent lamp (compliant with ISO 10977 or D65) + near-UV UV lamp (320-400 nm, peak 350-370 nm)
Option 2 is the most used in pharmaceutical laboratories because it is cheaper and easier to control.
The phases of the photostability test
ICH Q1B provides a sequential approach of up to 4 phases, from the unprotected product to the product in final packaging:
- Phase 1: active ingredient exposed directly to light (without protection)
- Phase 2: Finished pharmaceutical product directly exposed
- Phase 3: Product in primary packaging (blister, bottle)
- Stage 4: Product in secondary packaging (box, case)
If the product is stable in Phase 1, it is not necessary to proceed to the subsequent phases. If it is unstable, proceed to the next phase until the required level of protection is identified.
ICH Q1B and ICH Q1A: what is the relationship?
ICH Q1B complements ICH Q1A, which defines long-term and accelerated stability testing (temperature and humidity). Together, they form the complete package of stability testing required for drug registration:
- ICH Q1A: Thermal and humidity stability (25C/60% RH long-term, 40C/75% RH accelerated)
- ICH Q1B: light stable (photostable)
Both tests can be performed in the same ICH Q1A/B FDM chambers, equipped with both temperature/humidity control and a set of photostability lamps.
The FDM ICH Q1B test chamber
FDM Environment Makers offers specific chambers for the ICH Q1B photostability test:
- ICH Q1A/B chamber: control RHwith D65 + UV near-UV fluorescent lamp set, compliant with ICH Q1B Option 2 requirements
- Chambers with LCB-LCS illumination: equipped with programmable lamps, which can be used for photostability tests on cosmetics and materials
Each chamber is equipped with calibrated light sensors (lux meter and UV radiometer) to monitor and record cumulative exposure, ensuring compliance with the requirements of 1.2 million lux hours and 200 W h/m2.
Frequently Asked Questions about ICH Q1B
How long does an ICH Q1B test take?
The duration depends on the intensity of the light source. With 5,000-10,000 lux lamps, it takes approximately 120-240 hours (5-10 days) to reach 1.2 million lux hours. With more powerful lamps (20,000+ lux), the test is completed in 2-3 days.
Is the ICH Q1B test mandatory?
ICH Q1B is a guideline, not a law. However, the EMA and FDA require it as part of the registration dossier for new active ingredients and pharmaceutical products. In fact, it is mandatory for anyone wishing to register a drug in regulated markets.
Can I use the same chamber for ICH Q1A and Q1B?
Yes. The ICH Q1A/B FDM chambers are designed to perform both tests: the thermal/hygrometric stability test (Q1A) and the photostability test (Q1B) in the same chamber, simply by turning the lamp set on or off.
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Additional Authoritative Sources
- ICH Q1B Guideline — Official Document
- EMA — Photostability Testing Scientific Guideline
- FDA — Q1B Photostability Guidance
- ISO 10977 — Photographic storage conditions (reference for photostability of sensitive materials)
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