Unique unit-dose pack saves space and material costs for liquid pharmaceuticals

In 1997, Stone Pharmaceuticals set out to improve the convenience of its packaged unit-dose liquid pharmaceuticals while reducing storage and shipping space requirements--not an easy task given the existing state of unit-dose packaging.

The result was a unique packaging system that, in the end, also saved substantial material cost.

Introduced in November 1997, the new system consists of individually thermoformed 1-ounce vinyl cups made on equipment from Klockner Medipak which are held firmly together in 12-cup sets by a perforated, specially-engineered rigid lidstock developed by Reynolds Metals Flexible Packaging. The cups--each holding a 3/4-ounce or 25 milliliters (ml) liquid dose--are spaced so that one layer nests inverted within the second layer, reducing shipping and storage space by 50%.

But since the lidstock is perforated, each cup can be detached from the group and dispensed by lifting the lid via a convenient corner pull-tab.

Performance requirements for the lidstock were considerable. It had to (1) be rigid enough to hold the 12 cups; (2) resist aggressive components in the product that are in constant contact with the material (since half of each shipment would be upside down); and (3) maintain a tight seal, yet peel cleanly and easily without tearing.

The solution was to take a lidstock usually applied in hard-to-hold product situations--a heavy-gauge foil and film combination with a heat-seal coating--and modify it to meet Stone's requirements for aesthetics and functionality, then laminate it to a paper stock to achieve the peelability required.

The challenges weren't over yet. In production, the package faced exceptionally tight tolerance requirements because the "blisters" were to be formed in a continuous web, filled, sealed with the lidstock and only then cut out of the web. Registration had to be plus or minus 1mm. "This package," points out Stone Pharmaceutical's general manager Bob Malerman, "requires two to three times tighter tolerances than are typically acceptable."

For this precise operation Stone chose a Klockner Medipak Compacker 3 after seeing it demonstrated at a trade show. A major benefit of the equipment is its deep-draw capability, but also its quick changeover feature, since Stone also uses the equipment for producing conventional liquid and paste unit-dose packages, and because the company projects contract packaging duties for the line.

Tolerances were tight for the material as well. The blister cups needed a consistent thickness and a low moisture vapor transmission rate--low enough to allow up to 12 months of storage. The clear vinyl material chosen, Pentopharm[R] 575/08 from Klockner Pentaplast, has a thickness of 25 mil.

The advantages of the new packaging system over traditional liquid unit-dose are many. For the health care end-user, space is saved, dose measurement is eliminated, dispensing is simplified and tracking administered doses is easier.

Malerman points out, "Web production--as opposed to denesting individual cups, feeding the thermoformer and sealing with individual die-cut membranes--saves us about 30% in packaging production cost." That gives Stone Pharmaceuticals a distinct market advantage for its own products and, the company expects, will open the door for increased contract packaging opportunities as well.

For information from Klockner Medipak, call (813) 532-6512 or Circle 588. For information from Klockner Pentaplast, call (540) 832-1439 or Circle 589. For information from Reynolds Metals Flexible Packaging, call (804) 281-2262 or Circle 590.

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