Custom Routes to Package Desiccation

 By David Vaczek

While the prevalent use of bottle packaging in the United States continues to drive brisk growth in desiccant packets and canisters, desiccant manufacturers have devoted considerable resources to the development of alternative solutions to the drop-in model.

Multiform Coated Solid Form Sorbents

Desiccants in caps and stoppers provide replacements for drop-in sorbents in bottles. Desiccants are contained in strips fixed to blister packages, and moisture-absorbing films are available for use in foil laminations used in flexible packaging. Resin layers containing moisture absorbers are coextruded in­to bottles, and molded components of delivery devices can be made of desiccant-infused polymers.

One advantage of these approaches is that the patient can’t remove the desiccant, and thus leave the product unprotected. Also, they often can support loading in more desiccant than is feasible with a sachet or canister, providing the added protection often required by newer drug forms, such as powders and effervescents.

"Dissolving films, time-release capsules, and powder forms for drugs are gaining usage as OTC marketers in particular are seeking specialized packaging to set their products apart," says Mark Florez, global marketing manager for Süd-Chemie Performance Packaging (Belen, NM), a unit of Süd-Chemie Group. He notes that effervescent forms are used widely in Europe for fast action and full dose delivery for aspirin, vitamins, and sports supplements.

"Canisters and packets can’t be used with some of these newer drug delivery systems that are more hygroscopic than solid forms, and thus many new applications will require a desiccant polymer-based solution," Florez adds.

Desiccant OnBoard

Multisorb Technologies (Buffalo, NY) is offering customized desiccant solutions for respiratory drug delivery devices, such as dry powder inhalers (DPIs). A drop-in solution is used for systems employing drugs packaged in premeasured format such as in blisters, blister ribbon rolls, and capsules. Once a patient uses all the doses, they discard the device. The desiccant packet is placed with the doses in their secondary packaging.

On the other hand, reservoir-style DPIs measure out doses from a central chamber containing the drug amount needed to complete a regimen of dosing, such as 30 days. For desiccating these devices, Multisorb has launched a "fit-in" solution using new-generation Multiform Coated Solid Form (CSF) sorbents. CSF sorbents are compressed silica gel, carbon-blend structures incorporated into a predesigned cavity of the molded device, either in contact with the reservoir or separated by a membrane.

"We are developing different CSF solutions with customers, with the first one set to launch in 2008. The reservoir solution is more dynamic and difficult to protect, but it is also more convenient in that you don’t have to carry around the drug packets," says Adrian Possumato, global manager, pharmaceutical market, Multisorb Technologies.

DPI desiccating solutions typically have to hit a window of relative humidity (RH). Moisture levels must prevent product hydration and subsequent agglomeration of the particles. Yet excessive drying leads to electrification of particles in device systems that bring unlike materials such as plastics and foil into proximity. "If you aggressively go after the RH, you create static electricity that could reduce the amount of drug delivered," says Possumato.

The onboard desiccant in the reservoir dry power inhaler provides primary stability (for the foil-pouched device), and continuing protection once the device is unpackaged. "Companies using CSF as a fit-in solution will typically augment that with a sachet in the pouch that bears a good portion of the desiccant load for primary stability, preserving the CSF for the secondary stability profile (when the product is in use)," Possumato adds.

Süd-Chemie has debuted the Flow-Limiter, a solution that allows using bottle induction seals with desiccant cap applications.

The plastic device is secured into the cap below the induction seal. The Flow-Limiter drops into the neck of the bottle when the cap is torqued on. The spherical-shaped device features slots designed to allow one pill or capsule to be released at a time, minimizing product exposure to outside contaminants.

The Flow-Limiter can be made using Süd-Chemie’s latest generation of desiccant polymer. Besides controlling dispensing, it serves as a substitute for cotton fill, as the bell-shaped design keeps the product contained inside the bottle, says Bob Crossno, director of sales and marketing for the Americas.

"This is an induction-seal–friendly solution. We will work with pharmaceutical companies to customize the Flow-Limiter to their pill and bottle sizes, and desiccation needs," says Crossno.

Süd-Chemie has started injection molding operations in the United States at a new facility in New Milford, CT, in order to more cost-effectively supply the domestic market with printed tubes (cylindrical bottles), desiccant stoppers, and custom injection-molded solutions, says Crossno.

Custom projects are already under way with development of a molded dispenser for a medical device company. "The New Milford plant is designed around making packaging and dispensing systems for the pharmaceutical market. We will be supporting new delivery and packaging solutions that we expect will increasingly be sought for pharmaceutical and nutritional products," Crossno says.

These will include specialized containers that feature controlled dosing of solids and powders. Though U.S. drug manufactures have favored bottles, distinctive packaging forms have prevailed in Europe.

"We expect to see increasing emphasis in the United States on forms such as effervescent tablets," says Crossno.

CSP Technologies (Auburn, AL) has devised a desiccant solution for blister packaging in which a small piece of desiccant film is laminated to the foil lid stock above each blister well. Stability trials for foil/foil blisters are set to commence in July, says Billy Abrams, vice president, business development.

"Moisture issues can arise in high-barrier blisters using foil/foil, Aclar, and PVC/PVdC because of residual moisture in the dosage form or due to the ingression of moisture. This new solution becomes another way to discretely enhance stability for blister-packaged product," says Abrams.

Abrams says that Compass Pharma Services LLC (Clifton, NJ) has developed automation to support the application for formal stability trials.

The solution offers "a more sophisticated embodiment" of CSP’s modified atmosphere blister (MAB) solution, he says. A piece of CSP’s controlled desiccating polymer film is heat staked to the foil lid above each cavity, putting the desiccant film in direct contact with the dosage form. This supports a smaller blister footprint compared with MAB, where the firm’s Active Strip is affixed in a card cavity with channels running from the strip to each cavity. Unused wells stay sealed with the desiccant unexposed to ambient air. Tablets can still be pushed readily through the foil with the CSP film attached, and the film remains affixed to the foil upon opening, he says.

TricorBraun (St. Louis) is introducing DryKeep to the North American market. DryKeep is a desiccant entrained polymer that provides more protection per gram weight than typical desiccants that work by physical or chemical absorption, says Drew Williams, vice president, strategic markets.

Molded into the middle layer of an HDPE/LDPE bottle, the DryKeep application also accommodates the use of more desiccant in a package, for extending shelf life and providing moisture protection while the product is in use, Williams says.

"DryKeep absorbs 100% of its weight in water, compared with a typical desiccant that absorbs 40 to 50%. We can load in more desiccant, compared with standard canisters and sachets. For a 100-cm³ bottle with 0.3 g of water migrating into the bottle in a year, 4 g of DryKeep will maintain product freshness for 12 to 15 years," he says.

TricorBraun has licensed the technology from Sasaki Chemical (Japan). TricorBraun blends the magnesium sulfate–based desiccant material with a high- or low-density polyethylene, creating a compound for coextrusion into a blow-molded bottle.

"We have calculated that with a 4-gram load, you can open and close the bottle 1000 times and still maintain a 40% RH. We have successfully compounded the material and performed bottle testing," says Williams, noting that DryKeep is also suitable for flexible package applications.