Advances in Film Coating

Surveying the Landscape of Solid-Dosage Manufacturing

Experts take a look at the journey travelled thus far and where pharmaceutical manufacturing is heading over the next decade.

Film coating is a well-established unit operation in solid dosage form manufacture that offers many advantages for pharmaceutical products. Film coatings are applied onto tablets, multiparticulates and sometimes capsules or softgels to enhance their performance, protect the drug from the environment or achieve the desired immediate- (IR) or modified-release (MR) profile. Today, IR film coatings are most commonly used to impart a distinctive product appearance through colour and special effects, improve the ability to swallow and mask the unpleasant tastes or odours of drugs, as well as protect the drug from environmental factors.

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In 1980, Colorcon first launched Opadry, a fully formulated, ready-to-use film coating, which reduces raw-material inventory and improves process efficiency, while delivering batch-to-batch colour consistency. Since then, fully formulated IR film coatings have advanced to include new polymer systems that offer greater manufacturing efficiencies and better core protection, and the innovations are ongoing.

Newer film coatings enhance the mechanical properties of the tablets for their handling during packaging and transport by companies and patients. The majority of IR film coatings contain cellulosic ethers, such as hypromellose (HPMC) or/and polyvinyl alcohol (PVA), as the main film formers, with pigments for colour and plasticiser to enable film formation. Although PVA is highly hydrophilic, when used in film coating, it provides effective moisture barrier properties.

Recently, the US FDA has been focusing on strategies to reduce the number of medication errors and improve patient compliance (1). The key features and properties of IR film coatings not only minimise the risks of medication errors, leveraging pigments and colour for identification, but also, improve patient compliance through aesthetic appeal and the ease of swallowing.

There has also been a surge of interest in the pharmaceutical market to protect the tablet composition from moisture while ensuring a high productivity coating process. To meet the challenge of moisture sensitive drugs while ensuring better stability of the overall formulations, it has become more important to select a more specialised coating system.

Continuous processing is fast emerging as a real asset to oral solid dosage manufacture. With the advancement of machinery and optimised excipients, including film coatings, continuous processing and manufacturing of drug products are becoming more viable, acceptable and realistic for the pharmaceutical industry. Film coating for solid oral dosage forms continues to provide important patient benefits while enhancing brand recognition and adding value to innovator, generic, over-the-counter and nutritional products.

Reference
1. FDA Guidance for Industry, Safety Considerations for Product Design to Minimise Medication Errors (Rockville, MD, Dec. 2012).

About the Author
Ali Rajabi-Siahboomi, PhD, is vice-president and chief scientific officer at Colorcon.