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Changes in Tablet Color Due to Light Irradiation: Photodegradation of the Coating Polymer, Hypromellose, by Titanium Dioxide

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Abstract

The color of the tablets and capsules produced by pharmaceutical companies is important from the perspectives of product branding and counterfeiting. According to some studies, light can change tablet color during storage. In this study, tablets comprising amlodipine besylate (AB), a well-known light-sensitive drug, were coated with commonly used coating materials and exposed to light. Compared to the tablets that were not exposed to light, the color of those exposed to light changed over time. In fact, a faster and more pronounced color change was observed in the tablets exposed to light; however, the amount of AB did not decrease significantly in these tablets. The coating materials and their amounts were varied to clarify the materials involved in the color change. Based on the results, titanium dioxide and hypromellose may be involved in the color change process. As titanium dioxide is a photocatalyst, it may induce or promote chemical changes in hypromellose upon light irradiation. Overall, care should be exercised during selection of the coating polymer because titanium dioxide may promote photodegradation of the coatings while protecting the tablet’s active ingredient from light.

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Data Availability

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.

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Funding

This study was funded by Towa Pharmaceutical Co., Ltd and Kobe Pharmaceutical University.

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Authors and Affiliations

  1. Towa Pharmaceutical Co., Ltd, 26-7, Ichiban-Cho, Kadoma, Osaka, 571-0033, Japan

    Yuki Matsushima & Masaki Hattori

  2. Department of Pharmaceutical Technology, Kobe Pharmaceutical University, Kobe, Hyogo, 658-8558, Japan

    Akiko Tanaka, Tomoyuki Furubayashi & Toshiyasu Sakane

Authors
  1. Yuki Matsushima
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  2. Masaki Hattori
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  3. Akiko Tanaka
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  4. Tomoyuki Furubayashi
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  5. Toshiyasu Sakane
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Contributions

Y. Matsushima contributed to the study’s conception, the AB assay, the analysis of the decomposition product, SEM image acquisition, and preparation of the first draft of the manuscript. M. Hattori prepared and then coated the tablets. A. Tanaka and T. Furubayashi contributed to the experiment on light irradiation using the photostability chamber. T. Sakane revised and enhanced the language of the manuscript. All authors read and approved the final manuscript.

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Correspondence to Yuki Matsushima.

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Matsushima, Y., Hattori, M., Tanaka, A. et al. Changes in Tablet Color Due to Light Irradiation: Photodegradation of the Coating Polymer, Hypromellose, by Titanium Dioxide. AAPS PharmSciTech 25, 26 (2024). https://doi.org/10.1208/s12249-024-02732-x

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