A Fresh Coat: Innovation in Excipients - Pharmaceutical Technology

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PharmTech Europe

A Fresh Coat: Innovation in Excipients
Sophisticated excipient development, especially for coatings, is staying on top of new challenges and meeting expanding industry needs.

Pharmaceutical Technology
Volume 32, Issue 11, pp. 46-56

For example, consider the three important physical properties of coatings: strength, flexibility, and adhesion. "Making a coating with high film strength and high adhesion can be challenging because when you improve film strength, you have a negative effect on film adhesion and vice versa. So the challenge is to come up with a coating system that is a compromise between good enough film strength and good film adhesion characteristics that are required for that given application. Because typically when you manipulate the formulation, you gain something in one area and you lose something in another. There is a fine line between how much can you afford to give up in one area to gain something in another area," says Porter. "You can never say with a high degree of certainty that the formulation that seemed to have ideal properties for an application last week is going to be ideal for another similar application. There are so many variables. You might pick out a formulation today that meets 60% of the market needs and tomorrow it might be 20% and you have to come up with a variant of that formulation to meet those other 80%. The needs keep on changing. That's why having the database and the capability of manipulating it to meet these changing needs is so important."

The DOE database also factors in various process environments and the types of equipment. "The database gives us flexibility to make micro adjustments as necessary as we gain feedback information from customers. Having this information has allowed our regional labs to access this database and work at that customer interface level wherever they are. Anyone can access the database, the expertise is not centered within one or two individuals for ongoing business," says Brown. "Our interest educates our customers about what film coatings are and how they are tested, what they look like, and demystifying what these systems are really about, how they work, and why they work the way they do."

On-dosage differentiation

Figure 2: Using the basic principles of reflected light (top), Colorcon has developed pearlescent pigments (left). The effect of a subcoat color (e.g., light or dark tablet surface) influences the degree of pearlescence. (IMAGES ARE COURTESY OF COLORCON.)
The technical knowledge gained from particle engineering, polymer science, and statistical design is of critical importance as companies strive to establish brand recognition, combat counterfeiting, and prevent medication errors. There are easily visible distinguishing markers such as edible ink branding and two-dimensional barcodes that can be placed on individual tablets. Other technologies include coatings of unique color. Colorcon's aqueous film coating "Opadry fx," for example, is a pearlescent pigmentation that applies light-reflection principles with both dark and light tablet cores (see Figure 2).

Most anticounterfeiting efforts have focused on packaging, including radio frequency identification (RFID), holograms, and specialty labels. It is now equally, if not more, important to have on-dosage chemical and physical solutions built into the product. Chemical and physical taggants are covert technologies that can be added into a coating. "A chemical taggant may be an excipient that is not typically part of the coating formulation that acts as a marker within the coating at the parts per million or even parts per billion levels. "You can't detect that it's there through standard analytical technology unless you know it's there in the first place and you have specific systems that allow you to read it," says Schoneker. Physical taggants or microtaggants are particles that contain unique features or images. These microtaggants may be present at very low levels and can be easily assessed to determine authentic product versus a counterfeit. "In many cases, a counterfeiter wouldn't know these taggants are there. Or even if they knew they were there, they would have no ability to be able to make or get these unique microtaggants to try to counterfeit it," adds Schoneker. "It allows you to authenticate the products throughout the supply chain even if they have been repackaged or diverted."


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