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A coated solid format (CSF) concentrates twice the protection in the same dimensional space of a traditional, loose-fill desiccant canister Photo courtesy of Multisorb Technologies (Buffalo, NY).

By Adrian Possumato, Multisorb Technologies

It is an industry axiom that the number one threat to pharmaceutical stability is moisture and its effect on increasing molecular mobility. As such, incorporating desiccants into packaging for moisture control has been a long-established practice. An array of new solid-dose drug formulations, however, can reasonably be described as unstable, and therefore require special protection beyond the “traditional” moisture-controlling desiccant or oxygen scavenger. A number of molecules that are particularly moisture-sensitive or highly-oxidative have been shelved by drug manufacturers over the past 10 to 20 years because they could not be stabilized through reformulation and/or traditional packaging protection options. Thus, many promising drugs have been stopped in the pipeline for years.

Fortunately, manufacturers now have a number of new active packaging options for protecting increasingly unstable pharmaceutical formulations. Desiccants themselves are undergoing expanded usage and new applications. Technologies in moisture and oxygen control are helping to extend drug shelf life, improve brand quality and, most importantly, enable the marketing of drug products that had previously been considered too unstable. This includes the use of desiccants to reduce the rate of moisture-mediated oxidation. As the science of packaging protection evolves to meet new market demands, this article examines some new options and how they reflect changes and new challenges in the pharmaceutical industry.

New Desiccant Formats

Traditional desiccant formats for pharmaceuticals are sachets and canisters. While there is no question that these will continue to dominate the market worldwide, some new formats are, quite literally, taking shape.

One new desiccant format that offers an alternative is a coated solid format (CSF). Using compression technology, coated solids replace loose-fill formats by concentrating silica gel, activated carbon, or a combination of both to protect against degradation and adsorb volatilized hydrocarbons. A compressed solid, while having equivalent performance to traditional canisters, has no lid, eliminating any potential contamination from loose-fill desiccants spilling onto packaging lines. Because it can be shaped exactly like a canister, it can be substituted using existing dispensing equipment.

As the name implies, these formats are coated, and coatings are formulated to be smooth. This means there are no edges to get caught in machinery, and the coatings prevent any chalking or residue.

Concentrating Protection For Drug Formulations

A coated solid format is attracting attention from pharmaceutical manufacturers for reasons beyond production line efficiency, however. New drug formulations that are unstable may require high levels of protection. The standard operating procedure has been to increase the number of canister or packet drops per bottle, but this can become an impractical and expensive strategy.

Because coated solids are compressed, the format can offer up to twice the protection in the same dimensional space that a traditional desiccant canister provides. For drugs that require especially high levels of desiccant, this format can provide a cost-effective and efficient packaging solution.

New specialty oxygen absorbers eliminate oxygen from pharmaceutical packaging while managing moisture levels and protecting drug performance. Photo courtesy of Multisorb Technologies (Buffalo, NY).

Handling Highly-Oxidative Compounds

Pharmaceutical companies have risked losing a growing number of promising drug candidates before they go into clinical trials due to severe oxidation. A good example of an oxidative formulation includes new, reduced dosage hormone replacement drugs. For drugs such as these, traditional oxygen absorbers will not work in an HDPE package because they do not absorb moisture ingress through the bottle. Moisture ingress leads to excessive hydration, negatively affecting tablet dissolution.

To meet this challenge, new intelligent oxygen scavengers have been developed for products that strictly oxidize, enabling manufacturers to achieve drug stability without necessitating formulation changes. These new oxygen scavengers are unique because they are pre-loaded with a certain level of moisture. That may seem counter-intuitive, since the goal is to reduce moisture, but for these scavengers some moisture is required to act as a catalyst for the oxygen removal process. Typically, there is not much moisture in a pharmaceutical product, so by pre-loading oxygen scavengers with moisture, they act as effective oxygen absorbers in solid-dose HDPE bottle presentations. The moisture that comes in through the bottle continues the reaction, so a desired humidity level can be maintained in packaging.

This represents a more advanced technology than traditional oxygen scavengers because it removes oxygen while maintaining a specific equilibrium relative humidity within the package environment. The result: a product once considered too unstable can now be marketed.

Getting The Right Packaging Solution

Many of the new chemical entities being investigated today are very unstable and may suffer from chemical attrition via multiple pathways of degradation.

It stands to reason that as a result of this degradation, packaging protection needs to become more specific as well. The fact that new and better protection options are on the market clearly benefits drug manufacturers; however, it is more important than ever to rely on the scientific and engineering resources of packaging professionals. Desiccant and oxygen absorption options have been reformulated to keep pace with the new drug formulations entering the market. The trick is to make sure your packaging protection formulation is the right one.

About the Author: Adrian Possumato is the Pharmaceutical Market Business Development Leader with Multisorb Technologies, Inc. (Buffalo, NY). He works closely with drug innovators and generic pharmaceutical manufacturers in their R&D, quality, regulatory, engineering, and manufacturing departments to determine the best selection of packaged sorbents to stabilize pharmaceutical formulations. He has over 15 years of experience in the pharmaceutical and chemical industries. He can be reached at apossumato@multisorb.com, tel. 908-849-3005, fax 908-849-3006.

Pharmaceutical Processing
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