Impact of TiO₂-free film coating composition on the dissolution of poorly soluble and poorly permeable drugs

The growing interest in developing coatings for pharmaceutical products that are free of titanium dioxide (TiO₂) stems from concerns about potential health risks and resulting regulatory changes. Finding alternatives to TiO₂ is essential to meeting the requirements of the new guidelines. For generic drugs, maintaining compliance with the dissolution profiles of the reference drug is also important. This study evaluated the impact of different TiO₂-free coating formulations on the dissolution profiles and eligibility for a biological equivalence exemption of a BCS Class IV drug product in two strengths. Specifically, the study aimed to determine whether these coatings could replicate the dissolution profile of the reference product for the high-strength and meet the criteria for exemption from the bioequivalence requirement for the low strength. Tablet cores containing two BCS Class IV active ingredients were manufactured and coated with four different TiO₂-free coatings in two strengths. We evaluated the tablets' physical parameters and dissolution profiles. Similarity of the dissolution profiles was statistically evaluated in relation to the reference medicinal product and between different strengths. Different TiO₂-free coatings altered the dissolution profile of a BCS Class IV drug product depending on the testing environment. This variability suggests that some coatings may hinder dissolution, while others may facilitate it under certain conditions. These results underscore the importance of thoroughly testing different TiO₂-free coatings during the development of BCS Class IV drugs. The choice of coating should be tailored to the specific drug formulation and its intended use.