(T1230-11-72) Evaluation of Developmental TiO2 Free High Productivity and High Opacity Coating System at Different Scales

Purpose: Recently, the European Union (EU) has decided to suspend titanium dioxide (TiO2) as a food additive, classified as E171. TiO2 is a widely used material in the food and pharmaceutical industry as it provides opaqueness, brightness, aids in color matching, and protects active pharmaceutical ingredients from light degradation.¹ The EU decision has led formulators to seek alternatives to TiO2, and evaluate materials such as calcium carbonate and plant based opacifiers. High solids film coatings are preferred by many companies as they decrease coating time, through faster spray rates and less solution, creating a more efficient film coating. As a result, the shorter process time helps to protect friable cores by reducing the number of times the tablets tumble in a pan during the coating process. The aim of the study was to evaluate a new high productivity, high opacity TiO2 free system at different scales and understand the time savings associated with high solids.

Methods: The developmental coating was applied onto multivitamin cores using different size fully perforated side-vented coating pans from O’Hara Technologies: 15" and 24" (Labcoat II), and 48" (Fastcoat 48"). The process parameters are detailed in Table 1. The developmental formulas were evaluated at 15%, 20%, and 27.5% solid levels in water. In addition to visual appearance, gloss values were calculated using Model 801A Tricor Systems Inc Gloss Analysis System.

Results: This developmental high productivity formulation provides high opacity and is comparable to previously presented TiO2 free systems at 15%, 20%, and 27.5% solid levels.² The system has low viscosity (below 400 cp), even at the highest level of 27.5% solids. Additionally, with these formulations, coating time is reduced by 45% at all scales compared to 15% solids; and 27% compared to 20% solids, see Table 2 below. Although the spray rate for the 48" trial was 350 g/min (Table 1), it was possible to carry out additional trials with a spray rate of 450 g/min. A faster spray rate in combination with a 27.5% solids coating solution can reduce the total coating time to 42 min. In addition to this, calcium carbonate, when used at higher solids, usually results in lower gloss values. The gloss for the 24" trial hydrated at 27.5% solids was 58 GU which was significantly increased to 83 GU after 10 min of tumbling, producing glossier tablets. Elegant tablets, with a high quality finish, were obtained at all scales, Figure 1. These tablets were not tumbled to improve gloss.

Conclusion: The developmental high opacity film coatings were successfully coated in 15", 24" and 48" pans. These coatings are formulated to be hydrated up to 27.5% solids so that process time is decreased by 45%. To further improve the finished tablet appearance the multivitamin tablets can be tumbled for 10 min post coating.

References: Badger S, Ghimire, M and Rajabi-Siahboomi, A. Impact of Opacifier Type in a Film Coating Formulation on Photostability of Tablet Ingredients. AAPS 360 (2021). T1430-07-37.
2 Mehaffey T, Neeley C, Ghimire M, and Rajabi-Siahboomi, A. Comparison of three phases of Continuous Coater Operation during subsequent application of High Opacity Coating and High Gloss Coating onto Multivitamins. AAPS 360 (2021). M1530-03-17.

Table 1: Developmental Formulation Coating Parameters

Table 2: Coating Times of Developmental Formulation at Different Scales


Figure 1: High Productivity/ High Opacity TiO2 Free Film Coating at 3% and 4% WG using 27.5% Solids