Ajit Kanetkar, process technology head at ACG, tells EPM the evolving concepts and trends in tablet coating.
Pharmaceutical dosage forms have been around for centuries. Tablet dosage forms have dominated the sector as they are easy to manufacture, cost-effective and achieve improved acceptability and patient compliance.
Tablet coating was originally introduced to mask the bitter taste and odour of some medicines. At first, simple sugar coatings were applied followed by shellac which provided additional protection to ingredients that are sensitive to atmospheric moisture, light and oxygen.
Coatings continue to evolve and today’s drivers include product identity to help with promotion and product recall, protecting patients from the effects of active ingredients (APIs), drug loading, release profiles and modified release dosage forms.
Advanced film coating is currently the most widely used today. The new versions of coating materials allow a much higher concentration of coating materials in suspensions, where the solid content can be as high as 30% or more which drastically reduces processing times. Environmental and operational safety have contributed to a move towards aqueous-based coatings. The choice of coating materials includes new options such as cellulosic, acrylic and other polymers offering a range of drug release profiles.
The growing demand for coated tablets has focused pharmaceutical companies on equipment to handle large volumes of innovator products and generics.
Continual improvement in airflow design, drying and spraying systems has produced more efficient systems. Delivering spraying capability of maximum droplet size in a narrow band improves coating quality and consistency whilst minimising spray drying time and losses of expensive coating materials.
In addition to the regulator’s needs and user expectations of recipe management, access control, data compilation, trend analysis and new features are being added to controls. For equipment management, these include incorporating operating manuals and troubleshooting guidelines and drawings to facilitate ease of ordering parts and spares.
Control of intricate process parameters, increasing levels of automation and having critical information, easily available at any point in time, work towards better compliance to Quality by Design (QbD) and ICH guidelines delivering process optimisation and consistent results.
The application of ICH guidelines like Critical Material Attributes (CMA), Critical Process Parameters (CPP) and Critical Quality Attributes (CQA) contribute to achieving Quality Target Product Profile (QTPP). Supported by Process Analytical Technology (PAT) tools complete a robust and reliable coating system.
Evolving concepts in tablet coating include flexibility to produce multiple products in smaller volumes where equipment accommodates high to low batches with fast changeovers, continuous manufacturing, reduction in the residence time of tablets in equipment, increasing use of new modelling systems to study process parameters using data analysis and Industrial Internet of Things (IIoT). Other concepts include the adoption of low-cost generics and utilising coated tablets to extend the generics life-cycle, improved coating materials, and binding an insoluble API with a hydrophilic polymer to improve solubility and permeability. Finally, new coating materials without titanium dioxide are being developed following the European Food Safety Authority (under the broader European Commission) ban which is likely to trigger a review by regulators on its use in medicines and may invite a similar ban.
The introduction of products such as personalised and precision medicine and targeted delivery will continue to drive innovation and development in coating technologies, materials and processing.