Designing Blister Packaging for Tropical and Hot-Humid Climates

Products destined for tropical and hot-humid markets face the most demanding storage conditions in the ICH framework. Long-term storage at 30°C and 75% relative humidity imposes a continuous driving force for moisture ingress, and packaging that performs adequately elsewhere can fall short.

The Conditions Involved

Zone IVa and IVb cover large parts of Southeast Asia, South Asia, the Middle East, Africa, and Latin America. Long-term stability studies in these markets are typically conducted at 30°C / 65% RH or 30°C / 75% RH, with accelerated studies at 40°C / 75% RH.

For packaging, the key consequence is straightforward: the moisture gradient between the outside environment and the inside of the blister cavity is significantly larger than in temperate zones. Over a multi-year shelf life, that difference accumulates.

Where Standard Structures Fall Short

Standard PVC performs well at 21°C / 45% RH. In Zone IVb conditions, its water vapor transmission rate allows moisture to migrate into the cavity at a rate that can compromise products with modest stability margin. The result is typically seen as:

• Increased moisture content in the tablet or capsule
• Changes in hardness, friability, or dissolution profile
• Loss of appearance quality through sticking or discoloration
• Shortened effective shelf life versus the label claim

These effects are often only visible in stability studies conducted at the correct climatic conditions — which is why studying at the wrong condition can hide the problem until launch.

Structures That Work

Practical options, in ascending order of barrier performance:

Tropical-grade aluminum structures are engineered for these conditions, combining an aluminum barrier on the forming side with a compatible lidding web. Where transparency must be preserved for product inspection or brand reasons, our high-barrier PVC range offers a transparent alternative.

Lidding and Secondary Packaging

The forming film is only part of the system. For tropical distribution, also verify:

• Lidding seal strength after storage at elevated temperature
• Compatibility of the lidding lacquer with the forming film at your line conditions
• Whether the secondary carton contributes meaningful additional barrier
• Transport and warehousing conditions in the destination market

Testing Approach

Run stability studies at the actual target market conditions. If a product is distributed across multiple zones, the most demanding zone governs the packaging specification — packaging to the average requirement creates a failure risk in the most severe market.

Our technical team can match a structure to your stability data and target markets — contact us with your formulation details.