Temperature-sensitive shipments typically include wet ice, dry ice, or gel packs to help maintain refrigerated or frozen conditions inside the container. Wet ice is messy, and dry ice can be dangerous because it can burn exposed skin. All three traditional refrigerant options are relatively heavy and offer no cooling action once thawed. More active cooling is available from a gel-equipped fabric that is conditioned with water and frozen before packing in a process that can be automated for high-volume requirements. An active polymer in the gel holds water in suspension for 6–8 days and stays frozen for 25% longer than an equal mass in a gel pack. Even after thawing, the water sublimes through the fabric and continues to provide evaporative cooling to maintain safe product temperatures for twice as long as traditional refrigerants. The flat, flexible fabric also distributes cold more evenly through the container than wet ice, dry ice, or gel packs ("ThermaFreeze" refrigerant pads, ThermaFreezeProducts Corp., Theo-dore, AL).

Hallie Forcinio is Pharmaceutical Technology's Packaging Forum editor, 4708 Morningside Drive, Cleveland, OH 44109, tel. 216.351.5824, fax 216.351.5684, editorhal@cs.com
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