Originally Published PMPN February 2002
SPECIAL
Shipping Temperature-Sensitive ProductsValuable temperature-sensitive goods can be ruined by inadequate thermal packaging and the inevitable delays in the logistics chain.
Jenevieve Blair Polin, Contributing Editor
Through the frozen north in winter and burning deserts of summer, transportation of delicate pharmaceutical and biological products that can tolerate no such extremes is a challenge. Vaccines were once the most common temperature-sensitive pharmaceutical product, and their packaging continues to evolve, especially since some newer vaccines, such as the chicken pox vaccine, must be kept frozen. Genetically engineered, protein-based, temperature-sensitive drugs, however, are now also being manufactured and shipped, so the need for thermal packaging and engineering has never been greater.
Furthermore, points out Tom Pringle, managing director of the ISC Group of Tuscarora Inc., a subsidiary of SCA (Phoenix, AZ), FDA field inspectors are increasingly scrutinizing the control of the movement of temperature- sensitive materials within manufacturers' plants all the way through the complex distribution network, a path known as the cold chain. This scrutiny has fueled demand for product engineering and testing services to ensure development of thermal packaging that will meet manufacturers' claims for storage or transport temperature conditions. (See "Design and Testing of Thermal Protection Packaging")
KEEPING IT COLD
Expanded polystyrene. The standard approach to thermal packaging, Tuscarora's Pringle says, has been an expanded polystyrene (EPS) container combined with either dry ice or gel packs (either frozen water– based gel or phase-change material). Manufacturers continue to improve EPS containers. Polyfoam Packers, a division of Tuscarora (Wheeling, IL), for instance, has introduced its Stackers modular insulated shippers. A number of 2- or 3-in.-high rings can be added to the body to customize container size, reducing inventory needs for different sizes.
Phase-change materials and dry ice. Dry ice remains the favorite for holding frozen temperatures. "It's readily available, it's well understood, it's cheaper, and it keeps product cold longer, pound for pound, than phase-change materials," says Lawrence Gordon, president of FDC Packaging Inc. (Medfield, MA). Phase-change materials (PCMs) in the form of bricks or gel packs, however, offer advantages over dry ice for some uses. Bricks hold their shape to keep contents from shifting, as will happen when dry ice sublimates. Airlines limit the amount of dry ice a shipment may contain, and some products cannot tolerate the exposure to CO2 that occurs when dry ice sublimates. Frozen water–based gel ice packs are standard for maintaining refrigerated temperatures, says Pringle.
Phase-change materials are also available to achieve a widening range of temperatures. "We've found that customers are getting more stringent on the temperature range that they want to hold," says Kevin Grogan, market manager for Polyfoam Packers, a division of Tuscarora. His company has recently introduced a Max U-TEK gel that changes phase at –54ºC. "We've had a lot of success improving the insulating performance of the box," he adds, "but at some point you see diminishing returns and you also need to give [the boxes] an efficient phase-change pack to round out the solution."
"An ideal phase-change material is one that is as close to the desired operating temperature as possible, has a near-constant phase-change temperature, and has a high heat of fusion," explains Rick Hunter, director of product development for Kodiak Technologies Inc. (Houston). "The goal for us is to achieve a balance with the refrigerant and container system in a way that meets a market need. An example is our new –15°C PCM, which keeps products below –10°C for five days and freezes in conventional freezers."
Polyurethane. Polyurethane containers offer greater insulation than equivalent thicknesses of EPS. FDC's testing data indicate that its KoolGuard II, for instance, with 2-in.-thick polyurethane walls, holds freezing temperatures 40 hours longer (135 hours versus 95 hours) than a 2-in.-thick EPS container.
The American Red Cross (Washington, DC) distributes in excess of 10 million units of product to over 3000 customers annually, primarily in the United States, says Bob Wegmann, director of logistics operations. All their products are thermally sensitive but the range of temperatures required varies widely—from platelets, which require 20° to 24°C, down to frozen red blood cells, which require –65°C. To simplify matters, the Red Cross uses three standardized boxes from Tuscarora's ISC: the E-120, which is a 16 x 16 x 16-in. cube consisting of a removable wax-coated corrugated carton holding a solid insert of 1½-in. thick polyisocyanurate; the E-54, which is constructed of the same materials but is a 12 x 12 x 12-in. cube with a 1-in.-thick insert; and a platelet shipper. With red blood cells and other products that require similar temperatures, it uses wet ice; with the frozen products, dry ice.
They ship the frozen products almost exclusively via FedEx overnight, in part because FedEx does not restrict the quantity of dry ice shipped. But often, Wegmann says, overnight shipment is simply a necessity. "When you consider what we're shipping, it's essential that it gets there absolutely the quickest way."
Vacuum insulation panels. The Mercedes of thermal packaging is vacuum insulation panel (VIP) technology. The Dow Chemical Co. (Midland, MI) manufactures the Instill vacuum insulation core material and supplies it to a number of firms that create the panels and the finished containers. These VIPs provide far greater insulation (R-value of 30 per in.) than EPS or polyurethane.
In many cases, the total overall cost of shipping with VIP containers is less than it is with other forms of insulated containers, VIP fabricators assert, if one considers the combined savings that result from reductions in package weight and size and the longer shipment duration possible with VIPs.
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| Advantek's shipping containers with VIPs are thoroughly tested to ensure that specifications and life expectancies are met. |
Gary Schmidt, sales and marketing manager for VIPs for Advantek (Minnetonka, MN), offers as an example a customer that ships at dry ice temperatures. "When they use just plain EPS foam in a cardboard box, that package weighs approximately 22 lb, and most of that is dry ice. When that same product is shipped with VIPs, the total package weight is only 9 lb. The VIP container size itself is two inches smaller in each dimension. Instead of 3-in. EPS walls, it's just 1-in. VIP walls. Shipping costs are reduced by a switch to VIPs because an overnight shipment is now safe for second-day shipment."
Because vacuum insulation is so efficient, edge losses were a problem in early prototypes. In this phenomenon, heat travels in the metallized film or foil-based films around the VIP. The VacuPanel division of Energy Storage Technologies Inc. (Dayton, OH) has addressed this problem by engineering the Box-in-a-Bag. In a standard vacuum-insulated shipping box, five separate VIPs make up the box and a separate panel forms the lid. VacuPanel builds the 5-sided box, using fiberglass nails to attach the foam panels, then puts the entire box into the metallized film bag and evacuates the air to create the vacuum. With no butt joints, this design is not subject to edge losses. "We see about a 20% better performance than in the same-size box with five separate panels," says Chris Meyer, director of the VacuPanel division.
Significant improvements in the performance of Instill core VIPs have occurred in the last 18 months, thanks to film developments made by DuPont Teijin Films U.S. Limited Partnership (Wilmington DE), points out Kevin Weir, The Dow Chemical Co.'s business manager for Instill. With its Mylar SBL low-conductance metallized barrier film as the vacuum-holding panel exterior, edge losses have been virtually eliminated. This has raised the effective performance of Instill core VIPs to an R-value of 30 per in. and improved temperature holding capacity.
To prevent punctures, which can result in a loss of vacuum and insulating capacity, several companies have devised ways to minimize risks. VacuPanel's approach is V-Cladding. It applies polyurethane to the outside of the eight corners and top lid of the vacuum-insulated box, then puts it into a corrugated carton. Tuscarora's Polyfoam Packers, in its Deep Chill container, creates a four-layer sandwich— corrugated carton, molded EPS, VIPs, then another corrugated liner—to protect the VIPs both from the payload and from the external environment.
The ISC Group of Tuscarora incorporates the VacIntact vacuum indicator, for which it recently received the Ameristar Award through the Institute of Packaging Professionals, into its VIP containers. The device is "like a turkey popup [thermometer]," explains Tuscarora's Pringle. "If it pops up, you know the vacuum is gone." This monitoring offers reassurance that is particularly important, he notes, with VIP containers, which are often repeatedly reused because of their high value.
Kodiak takes reusability one step further. Last year the company launched the Cold Chain Shipping System, based on rental of vacuum-insulated containers and a logistics service. The Kodiak reusable shipping container incorporates continuous temperature monitoring and active temperature control. "This technology enables extended environmental excursions below zero without the risk of freezing the product, does not require the addition of thermal mass, and requires no power to operate," explains Kodiak's Hunter.
Customers order the containers and pack them when they arrive at their facility, then track and monitor their shipments and obtain temperature reports through Kodiak's Web site. Kodiak retrieves the empty containers from the recipient and then inspects and cleans them. The largest container has a capacity of 1.36 cubic feet, or about 37 L. "That's all usable volume, because the phase-change material is in the lid itself," explains Tony Gie, Kodiak's vice president of sales. The container maintains desired temperature for five to six days, expanding the shipping week and transportation options.
KEEPING IT WARM
Keeping products frozen or refrigerated is a challenge, but keeping products from freezing is often a greater challenge. The platelets shipped by the American Red Cross are one such product that cannot tolerate freezing. Phase-change gel packs surround the platelets to buffer them from cold.
"Instead of freezing the gel packs, you use them as a heat sink," Tuscarora's Pringle explains, "and you take advantage of their large thermal mass." In this case, he says, a 50-mL bag of platelets is surrounded by 12 lb of room-temperature gel. For the blood platelets to drop a degree, the entire 12 lb of gel has to drop a degree. This mass is placed inside a highly insulative container, the platelet shipper, which has 3-in.-thick polyurethane walls.
Even refrigerated products need protection from freezing. "Placing a frozen ice pack or dry ice next to a refrigerated vial or syringe in a thermal container can easily cause the product to freeze," Pringle says. Frigid ambient temperatures during winter months, which may be as low as –10°C in ground-freight carriers, are a similar hazard. Adding thermal mass in the form of room-temperature or refrigerated packs to the packout, Pringle says, is the solution.
The latest generation in phase-change materials offers further options for maintaining warm temperatures. While those that change phase at low temperatures, such as –10°C, have been available for years, some that change phase at room temperature have just come on the market. FDC Packaging offers a material that changes phase at 20°C, and Tuscarora's Polyfoam Packers sells one that changes phase at 29°C.
Advantek's Schmidt also emphasizes the advantages of using a single standard versatile shipping container but varying the packing configuration. "The standard VacuLok shipper is effective for both warm and cold applications with just a change of the phase-change material. I had a customer tell me they received a shipment of warm living cells in a VIP container one day and the next day received an identical VIP container shipment packed out with a product in dry ice," he says.
FedEx Custom Critical (Akron, OH) found protection from freezing to be such a high priority for its customers that since 1993 it has built a fleet of 180 climate-controlled vehicles. The catch is that the shipper must consign the entire vehicle, because there is no commingling of freight. "Two or three pallets of a pharmaceutical may be a huge supply," admits Jim Snider, vice president and general manager. Therefore, only about 35 of the vehicles in the fleet are tractor-trailers. "Our smallest trucks hold 5000 lb and probably can accommodate six skids side by side. The larger straight trucks can handle up to 13,000 lb and probably ten skids, and then the tractor-trailers up to 40,000 lb and probably 24 skids," Snider estimates.
FedEx Custom Critical also offers the capability of building decks. "We can maximize the truck's cube capacity," he says, even when the items shipped are lightweight and cannot be double stacked.
One major pharmaceutical firm does its end-of-year product rollouts exclusively with FedEx Custom Critical. "It may have 200 of our trucks, some climate-controlled and some not, and in three days, we'll make 1000 deliveries. Each truck will have 6, 8, 10, 15 stops on one trip, but the driver just makes a milk run delivering to each of these retail outlets. The cost per delivered unit is reduced substantially, so yes, you're paying for the whole truck, but the more deliveries you can put on a single unit, the more cost-effective it becomes," Snider adds.
Copyright ©2002 Pharmaceutical & Medical Packaging News
