Film coated tablets offer numerous advantages. They mask unpleasant tastes, protect active ingredients, improve swallowability, and provide an attractive appearance that enhances patient compliance. However, defects can turn a perfectly good batch of film coated tablets into a rejected product. Whether you’re dealing with peeling, breakage, colour variation, or surface defects, quality coating results from the right formulation of tablets, correct process settings, and reliable pharmaceutical processing equipment.
Common Defects in Film Coated Tablets and How to Fix Them
Peeling
Peeling happens when the coating lifts from the tablet surface. Overheating, poor film formulation, or weak plasticisation are usual culprits. Lower pre-warm temperatures in your tablet coating machine, and select a well-plasticised coating system. Improving core quality through better formulation or a smoother tablet press finish also helps.
Breakage
Broken tablets lead to contamination and yield loss. This can result from soft cores or excessive pan speed. Optimise your coating equipment settings by reducing pan speed, increasing spray rate, and increasing suspension solids concentration.
Logo Bridging
Coating that spans over debossed logos reduces identification clarity. Use higher adhesion coating materials, refine the logo design, and adjust the spray rate and atomisation pressure to help droplets reach finer details.
Twinning
When tablets stick together, twinning is the result. Increasing pan speed, boosting airflow, and reducing the spray rate can minimise twinning. Adjusting the tablet shape with your tablet press machine is the best long-term fix.
Surface Erosion or Edge Erosion
Erosion occurs when fragile cores suffer during coating. Edge erosion specifically affects tablet edges, particularly with sharp edges or inadequate protection. Reduce friability through formulation improvements, and consider equipment such as the PACCO High-Speed Mixer, PACCO Ribbon Blender, or PACCO Mill for better granulation and particle uniformity.
Colour Variation on Individual Tablets
Colour variation on single tablets appears as mottling or streaking. This results from poorly dispersed pigments, ingredient interactions, or plasticiser migration. Select a high-opacity coating, increase bed temperature, and use a seal coat to prevent colour instability.
Tablet-to-Tablet Colour Variation
Tablet-to-tablet colour differences are caused by uneven coating distribution during the process. Achieve a more uniform finish by improving tablet movement with a higher pan speed, fine-tuning your spray gun setup, adjusting solids concentration, and selecting a high-opacity coating. The PACCO Coater system helps ensure uniformity with its fully integrated design, featuring clean, filtered airflow, PLC-controlled operation, and efficient fluid delivery through a peristaltic pump.
Film Cracking
Film cracking weakens both protection and appearance. It is often linked to poorly plasticised coatings, excessive core expansion, or insufficient relaxation time. Use a well-plasticised film system, avoid overheating the tablet bed, and allow adequate time between tableting and coating so the cores can stabilise.
Spray Drying
Spray drying occurs when droplets dry before reaching the tablet surface, causing rough textures or filled-in logos. Reduce the atomisation air pressure, lower drying temperature, and position spray guns closer to the tablet bed to ensure droplets remain wet long enough for proper film formation.
Picking and Sticking
Picking and sticking happen when coating material adheres to pan surfaces or pulls away from the tablet. Improve adhesion by using high-solids formulations, reduce spray rate, and increase drying temperature and airflow. The PACCO Fluid Bed Dryer ensures uniform drying through its controlled environment, providing even distribution of the drying medium and consistent moisture levels before coating.
Orange Peel Roughness
Orange peel results in a rough, dimpled surface and is typically caused by high suspension viscosity or poor atomisation. Select lower-viscosity coatings, decrease suspension concentration, and optimise atomisation pressure and spray rate to achieve a smoother finish.
Processing Machinery for Quality Pharmaceutical Manufacturing
Consistent film coated tablets depend on accurate process control and reliable pharmaceutical equipment. When blending, granulation, compression, and coating are all handled precisely, defects are reduced and coating becomes more predictable. PACCO processing machinery helps manufacturers maintain stable, repeatable settings such as pan speed, temperature, and airflow for achieving uniform, defect-free film coated tablets.
A well-prepared formulation from a PACCO blender or mill creates stronger tablet cores that withstand the coating process, while a Piab pharmaceutical vacuum conveyor streamlines material handling and reduces contamination risk.
PA Cuthbert provides a complete range of pharmaceutical manufacturing solutions and is a proud supplier of Colorcon film coatings. Together, the right processing equipment and coating materials enable manufacturers to produce smooth, durable, and visually appealing film coated tablets.
