Medical Device Link.

Originally Published PMPN July 2001

New Markets, New Formats for Desiccants

Desiccants are cheap insurance for products with any hint of stability problems.

Jenevieve Blair Polin, Contributing Editor

Growing demands for desiccants have driven manufacturers across the United States to invest millions of dollars in new equipment to increase the capacity as well as the quality and variety of the desiccants they produce. Suppliers are offering desiccants in a multitude of forms, ranging from packets to canisters to desiccant-impregnated packages, to help meet the needs of industry.

Süd-Chemie's high-capacity desiccant-canister filling lines can produce up to 1000 canisters per minute.

Last fall, Süd-Chemie Performance Packaging (Belen, NM) added high-capacity desiccant-canister filling lines, which can produce up to 1000 canisters per minute, to cut delivery time projections and improve quality by using state-of-the-art vision systems. In addition, says Robert Crossno, Süd-Chemie's national sales manager, the company has added high-capacity desiccant-packet filling lines, which can produce 8 to 12 packets or 8 to 12 reels at once.

Multisorb Technologies Inc. (Buffalo, NY) has seen similar growth, increasing output by 20% over the past three years. Rod Dobson, technical sales representative for Multisorb, proposes several explanations for the growing demand for desiccants. One is the harmonization of global standards. "Through some of that harmonization," Dobson says, "the requirements for moisture-related stability testing are a bit more stringent than they used to be, so we're seeing more products failing the stability tests now." Furthermore, pharmaceutical engineers are developing more-sophisticated compounds, "and they are better understanding the degradation pathways—how a drug goes about failing," says Dobson. "As they do that, they are putting in desiccants because the development costs are so great for the pharmaceutical product that the desiccant is really a pretty cheap insurance policy."

Desiccare Inc. (Sante Fe Springs, CA) has also experienced growth in the past few years. Brad Wolk, director of sales and marketing, attributes some of that growth to the understanding that "a desiccant is no longer a luxury item, but rather a critical packaging component." He adds, "Changing the mindset of many packaging professionals around the world has taken some time, but it is now paying off for us."

WHY CANISTERS?

The silica gel Sorb-It canisters from Süd-Chemie are well suited for high-speed automatic insertion in specialized packaging operations.

Gilead Sciences Inc. (Foster City, CA) is a pharmaceutical company with two sophisticated drugs in late phase 3 development. Both are antivirals—one for HIV and the other for hepatitis B virus—and both are hygroscopic. Ken Kinzler, Gilead's manager of clinical and commercial packaging, describes the three-pronged approach his company has taken to safeguard the products. Both products are tablet dosage forms and are packaged into thick-walled 60-cm³ high-density polyethylene bottles, which reduce moisture permeation through the bottle. A 1-g Süd-Chemie silica gel Sorb-It canister is added for one product, and three 1-g Sorb-It canisters are added for the other product. Both also receive a polyester packing material and a child-resistant closure with a tamper-evident induction seal.

"Our choice of the canister was market driven," Kinzler says. "A canister is more elegant and durable than a sachet. We also kept in mind that patients are paying a premium for the medication. When machining sachets, you always have the higher probability of slicing open a sachet, thereby introducing silica gel into the package. We certainly don't want any of our patients opening up one of our bottles and finding silica gel mixed in their medication."

WHY PACKETS?

Desiccant-packet manufacturers have worked hard to eliminate the specter of sliced packets spewing desiccant. Their efforts have focused on improving the seal between packets and increasing the ability of vision systems on automated cutters to detect the seal area reliably.

Multisorb's approach has been to improve the clarity of the windows in the seal, created by sealing Tyvek to itself. Süd-Chemie, which makes packets from GDT2 and Tyvek, punches a hole in the seal between packets. A photoelectric beam detects either the clear seal window or the hole. A system that relies on seal windows, cautions Süd-Chemie's Crossno, may fail to detect a window that is less than optimally clear. With one that relies on a hole, however, "if you get any drift whatsoever in the packets as the strip goes through the machine, the photoelectric eye can potentially miss that hole," counters Multisorb's Dobson.

Other subtle differences may also affect the quality or performance of packets. When DuPont introduced Tyvek 1025B a few years ago as a less-expensive and lighter-weight alternative to 1059B, many desiccant-packet manufacturers tried it. Scott Fredrick, COO of Phoenix Health Care Products LLC (Milwaukee), a converter, says Tyvek 1025B now accounts for a growing portion of their sales to desiccant-packet manufac-turers. However, Susan Cantwell, Phoenix's R&D manager, says some of these manufacturers have reported initial start-up problems with the new material.

Multisorb's Dobson agrees, saying 1025B is less expensive but not as easy to work with as 1059. "The part that we don't like on any Tyvek material, or almost any kind of spunbonded material, is the variation in density. We like all our products to be as uniform as possible so that we can have uniform characteristics. Tyvek 1025B tends to be even more variable than the others," he says.

Packets constructed of materials other than Tyvek, but similar to paper, may present other problems. According to Dobson, they may have a greater tendency toward dusting, a greater likelihood of fibers breaking loose, lower durability, and poorer printability.

The main appeal of packets is their cost, which can be up to 30% less than that of canisters. On the flip side, canisters can be dispensed at a faster rate, which can also result in cost savings through improved productivity. While a company like Gilead may find canisters the best choice for an expensive new pharmaceutical, Dobson explains, "we've seen the growth in packets versus canisters for those companies trying to squeeze cost out of products because they're coming off patent and now they've got to compete with the generics." The payback on investment in machines that handle reels of packets, Dobson adds, can be from as little as a few months up to 18 months.

Süd Chemie is improving quality by using state-of-the-art vision systems on its desiccant-canister filling lines.

WHY DESICCANT-IMPREGNATED PACKAGES?

For elegant products demanding elegant solutions, however, desiccants themselves have become more sophisticated. Packaging for diagnostic test strips, a high-volume commodity item, is a microcosm demonstrating some of the latest developments in the desiccant market. One is the use of vials lined with a polymer film impregnated with desiccant.

"Beginning this year, a number of major blood-glucose test strips will be sold in CSP vials, and that number will continue to grow," says Billy Abrams, vice president, business development for CSP Technologies Inc. (Auburn, AL). CSP manufactures these vials using an engineered polymer technology—adding particles (e.g., desiccants) and a channeling agent to any base polymer, polypropylene or polyethylene for example, to create a desiccating polymer film. (See "Desiccating Polymer Films" sidebar.) The film's interconnecting transmitting channels enable full utilization of the active particulates and control of the rate of uptake. With a two-shot molding process, they shoot the desiccant liner first and then shoot the vial shell over the liner. The liner is therefore an integral part of the container. In addition, CSP's patented technology can be used to absorb oxygen or other harmful substances.

Süd-Chemie offers a competing technology called "2AP." The company has dual injection-molding equipment using the 2AP technology to produce the entire housing for an ovulation test kit, among other products. Multisorb, in turn, offers SLF, or sorbent-loaded film, another competing technology.

The desiccant-impregnated films, like any new technology, present some challenges. Joachim Ruckdeschel, technical and project engineer for Sanner of America, a subsidiary of Friedrich Sanner GmbH and Company, KG (Bensheim, Germany) and a manufacturer of vials and desiccant stoppers for diagnostic test strips, mentions some concerns with this new technology: Will the new technology slow validation or FDA clearance? If the components are in direct contact with the diagnostic or pharmaceutical product, are they compatible?

IMPROVING PACKAGE SEALS

Desiccare's DrySpy PillowPaks feature an incorporated security source tag in the desiccant packet.

With absorption rates being very much of a concern for manufacturers of desiccant-impregnated packages, ensuring a tight package seal is paramount. As a further enhancement to its desiccant-lined vials, CSP by a patented process closes the vials in the mold. The vial with its flip-top closure is a single molded unit. "By closing the vials in the mold, before the material has fully set, we let the natural shrinkage properties of the materials take over, and that is what enables the seal," explains Abrams.

One end-user advantage of flip-top closures for desiccant-lined vials is ease of use, especially for elderly patients. Patients who have a hard time removing a cap or stopper, says Abrams, are reluctant to reclose the vial properly, which can compromise the quality of the product.

Sanner of America is also addressing the concerns of maintaining a tight seal in its desiccant packaging. "We strive to continuously improve our desiccant packaging for diagnostic test strips, pharmaceuticals, and nutritional products, while allowing the consumer to open the package with relative ease," says Jim Luchsinger, sales manager for Sanner of America.

"For pharmaceutical or nutritional packaging, we also incorporate a sealing system inside our screw closures to seal the package from the inside out like a stopper seals a vial," Luchsinger explains. "That eliminates the need for an induction seal. One problem with an induction seal is that the moment it is open, you have a rough surface on the outside of your bottle, whereas with our system every time you reclose it, you have a nearly perfect seal between the closure and the bottle," he adds.

THE NEXT BIG THING

"Light, oxygen, and moisture, together or separately, may cause degradation of almost any product," Dobson asserts. "Light obviously has been addressed through the formulation of the bottles. Desiccants are taking care of moisture, but nobody has really been focusing very much on the oxygen part."

The next leap, many in the field predict, will be for so-called "active packaging," incorporating oxygen scavengers. Desiccare's Wolk calls these multipurpose products "smart desiccants." Also, Desiccare's new line of DrySpy PillowPaks, which incorporates a security source tag into a desiccant packet, is another example of what suppliers are doing to cut down on costs by improving productivity.

Copyright ©2001 Pharmaceutical & Medical Packaging News