Film, Sugar and Enteric Tablet Coating: Practical Guide
In modern solid dosage manufacturing, tablet coating is far more than a cosmetic step. A well-designed coating layer protects sensitive active ingredients, improves stability, masks unpleasant taste and odour, and helps patients identify and swallow tablets more easily. Among all techniques used today, film coating, sugar coating and enteric coating are the three classic approaches that most formulators and manufacturing engineers work with every day. For equipment suppliers and production teams, understanding when and how to use each coating type is essential for designing robust processes and choosing the right coating machinery. 1. What is tablet coating and what does it do? Tablet coating is the process of applying one or more thin layers of polymers, sugars, waxes or functional excipients onto compressed cores. The coating solution or suspension is sprayed onto tablets while they tumble in a rotating perforated pan or move through another type of coating system. Warm, conditioned air dries the deposited droplets to form a uniform surface layer that changes how the tablet behaves in the hand, in the blister and in the patient’s body. At the simplest level, coating prevents mechanical damage, reduces dust, and makes tablets look smooth and uniform. In more advanced applications, coating controls how fast the drug dissolves, where it is released in the gastrointestinal tract, and how well the product can survive moisture, light and oxygen during its shelf life. Because coating touches both formulation science and process engineering, it is one of the key links between R&D, production and packaging. 2. Film coating - the modern standard Film coating has become the dominant approach for most new tablet products. In this method, a relatively thin polymer layer is sprayed onto the cores, usually from a water-based dispersion. Typical film-forming polymers include HPMC, PVA and acrylic systems, combined with plasticisers, colourants and sometimes functional pigments for opacity or light protection. Compared with older technologies, film coating offers several practical advantages. The coating layer is thin and light, so tablet size and weight only increase modestly. Processing time is relatively short, which helps keep batch cycle time under control and supports high throughput production. The technology is compatible with automatic control of inlet air temperature, spray rate, pan speed and exhaust conditions, making it easier to run consistent, repeatable batches. For many products, a simple non-functional film is enough to improve swallowability, mask mild taste and prevent scuffing in bottles and blisters. In addition, film coated tablets are often the best partner for blister packaging lines. Because the surface is smooth, hard enough and not excessively fragile, they flow well through feeding systems and can withstand sealing forces in the blister machine. When the formulation r...