ICH Q1A Stability Testing: What It Means for Your Packaging Material Choice

ICH Q1A defines the stability testing conditions that support pharmaceutical product registration. Its climatic zone framework has a direct, practical consequence for packaging material selection — and it is often the reason a material that performs well in one market fails in another.

The Climatic Zones

ICH divides the world into five climatic zones based on long-term temperature and humidity conditions:

• Zone I — Temperate: 21°C / 45% RH
• Zone II — Subtropical and Mediterranean: 25°C / 60% RH
• Zone III — Hot and dry: 30°C / 35% RH
• Zone IVa — Hot and humid: 30°C / 65% RH
• Zone IVb — Hot and very humid: 30°C / 75% RH

Long-term stability studies are conducted at the conditions of the target markets. A product intended for Southeast Asia, parts of Latin America, or the Middle East will typically be studied at Zone IVb conditions.

Why This Drives Packaging Choice

At 30°C and 75% RH, the driving force for moisture ingress into a blister cavity is far higher than at 25°C and 60% RH. Materials that pass Zone II stability studies with standard PVC can show unacceptable moisture uptake when the same product is studied at Zone IVb.

This is the most common reason companies return to material selection late in development — after a stability failure rather than before it. Choosing the barrier level with the distribution climate in mind avoids that rework.

Practical guidance:

• Products destined for hot-humid markets should generally be evaluated with PVDC-coated, high-barrier, or cold-form aluminum structures from the outset.
• Our tropical-grade aluminum range is specifically designed for Zone IVa and IVb distribution.
• Where transparency must be retained, high-barrier laminates are the usual answer.

Documentation to Request

To support your stability program and regulatory submissions, ask your packaging supplier for:

• A technical data sheet with WVTR and OTR values measured to a defined method
• A compendial compliance statement covering USP <661.1>/<661.2> and EP 3.1/3.2 as applicable
• Batch certificates of analysis for each delivery
• A change control commitment covering formulation, process, and site changes

These documents are what regulators expect to see alongside your own stability data. Our standard documentation package is summarized on the certifications page.

Getting the Sequence Right

The efficient sequence is: define target markets, derive the required barrier performance from the climatic zone, select materials, and then run stability studies on the chosen primary packaging. Doing it in that order keeps packaging decisions inside the development timeline rather than on the critical path at the end.