Alu-Alu or PVC-Alu: choosing a blister for the market, not the budget

Two blister formats cover almost the whole solid oral catalogue. The difference between them is a moisture barrier, and in a tropical market that barrier is your shelf life.

What actually separates them

PVC-Alu is a thermoformed PVC cavity with an aluminium lidding foil. The lid is a total barrier; the cavity is not. Moisture and oxygen reach the tablet through the PVC, slowly, over the product's life.

Alu-Alu — cold-formed aluminium on both faces — is effectively a total barrier on both sides. Nothing gets in through the pack. Its cost is real: the cavities are larger, so fewer fit per blister and the pack is bulkier, and cold forming is slower than thermoforming.

Where the choice gets made

For most immediate-release products in temperate markets, PVC-Alu is correct and Alu-Alu is over-specification. The decision turns the moment one of these is true:

• The molecule is hygroscopic. Many effervescent formulations, some anti-diabetics and most enteric-coated products lose their stability profile behind PVC.
• The market is Zone IVb. Much of ASEAN, and much of coastal India, is tested at 30 °C and 75% relative humidity. A product that holds 24 months in Zone II may not hold 18 in Zone IVb behind the same pack.
• The claim you want is 36 months. Registration is where this becomes concrete: the shelf life you can claim is the one your stability data supports in the pack you filed.

Why it is decided too late

Because packaging is priced per pack and stability is measured in months. The unit-cost difference is visible on the first quotation; the stability consequence is visible a year into a study, when changing the pack means repeating it.

Our catalogue states the format for every line — and for several products it states both, because the right answer genuinely differs by market. If a product is going to Zone IVb, that is a conversation to have before the first stability batch, not after.