A summary of the poster presented at the European Coating Symposium
September 17-19, 2003 at the University of Freiburg, Switzerland

Coating technology is used extensively in the pharmaceutical industry, e.g. for the application of non-functional or functional coats (aesthetic, protective or rate controlling polymer films) and for the deposition of Active Pharmaceutical Ingredients (APIs) onto nonpareils (multi-particulate dosage forms). In addition to efficient techniques for API layering of multiparticulate systems, an accurate method of coating objects 3 to 30 mm in length with APIs is also desired in the pharmaceutical industry as this is the size range of most single-unit solid dosage forms. These include tablets for oral administration and forms for other methods of delivery including human implantation.

Existing methods of coating objects in this size range have limitations, e.g. in terms of coating speed and accuracy/uniformity, particularly for the deposition of low dose API onto single unit tablet dosage forms which requires a greater degree of accuracy than can be achieved using current tablet coating techniques.

A novel method of coating small objects has been developed that has demonstrated the ability to uniformly coat inert objects of sizes between 3 and 30 mm in length with a high degree of
accuracy. Using the coating method, Relative Standard Deviations (RSDs) below 2% have been achieved for total coating contents as low as 200 micrograms per object. However, it is unknown how accurately the deposition will be on conventional pharmaceutical tablets (which have a higher degree of friability and more irregular surface compared to the inert objects used).

Methods of evaluating coating uniformity include mass variance of the coated tablets and variance of the tablet API content2-4. However, the United States Pharmacopoeia (USP) states that “The test for content uniformity is required for coated tablets, other than film-coated tablets containing 50 mg or more of an active ingredient that comprises 50% or more (by weight) of one tablet.”4 In this study, the RSD of the API content will be used to evaluate the inter-tablet coating uniformity of this novel coating method in applying low doses of API onto conventional tablets.

Conducted and presented by:
Andrew P. Birkmire  - GEA Pharma Systems, Niro Inc.
Celine V. Liew  - GEA Pharma Technologies, Niro Inc.
Department of Pharmacy National University of Singapore

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