Film coating: mastering formulation and process

Mastering the formulation and coating process is a strategic challenge for the pharmaceutical and nutraceutical industries. 

This process, which involves applying a thin protective or functional layer to tablets or capsules, plays a key role in the efficacy, stability and aesthetics of finished products. This layer, 20 to 100 µm thick, represents approximately 1 to 10% of the tablet’s initial weight.

From the selection of laminating agents to the optimization of production parameters, each step requires specialized expertise to ensure consistent results in line with market requirements.

This article explores in detail the basics of the formulation and lamination process, to provide a clear understanding of the key elements of this essential process.

Film coating formulation

The film-coating formulation combines four key ingredients:

• A film-forming polymer, which provides the mechanical strength of the film. The most widely used polymers in non-functional film coating are cellulose derivatives such as hypromellose.

• Plasticizers, used to improve the flexibility of the film formed and prevent it from cracking or breaking. They work by weakening the attraction between the polymer molecules to make the film more malleable.

• Coloring agents, which increase opacity, protect from light, and color the film.

• Fillers, which can be added to reduce tack and improve slip, or to adjust the content of insoluble materials in the coating composition.

Tianjin Jiahui draws on in-depth knowledge of these different parameters of the coating stage, and its expertise in formulation, to develop robust, efficient, and ready-to-use formulations to facilitate the coating process of its customers. 

These formulations combine a film-forming polymer, plasticizer, and fillers, either with or without coloring agents, with appropriate grades selected and optimized proportions.

The tablet coating process

Coating technology involves having an expansive knowledge of ingredients and their interactions, expertise in formulation and in the various coating processes, in order to produce a smooth, regular and homogeneous film that completely covers the surface of the tablet. This requires the interaction between three elements:

• The tablet core, designed to withstand the mechanical stresses applied during the coating process and to facilitate the adhesion of the film to the tablet’s surface. The tablet’s shape strongly influences the mixing characteristics in the film-coating turbine and the uniformity of the final film on the tablets.

• Formulation of the coating, with its composition and viscosity.

The coating process, and equipment, which strikes a delicate balance between atomization of the coating dispersion, and drying. The final quality of the film-coated tablets relies on critical process parameters.

Jiarui expertise

Tianjin Jiahui Jierui Pharmaceutical Technology Co., Ltd. has been deeply engaged in the pharmaceutical excipient industry for more than 20 years. It is a high-tech enterprise in China that holds both pharmaceutical and food qualification certificates simultaneously. Currently, it has established strategic cooperative partnerships with a number of well-known health product and pharmaceutical enterprises around the world.

Jiahui Company has always adhered to the innovation-driven development strategy, with a Tianjin Technology R&D Center and a Shanghai Technology R&D Center established. The R&D team accounts for more than 28% of the total staff, and it has accumulated 36 authorized patents. The core products have been tested by authoritative institutions, and their key performance indicators comply with pharmacopoeia standards. Upholding the principle of "Quality First, Win-Win Cooperation, Understand Your Needs, and Give You What You Love", the company is committed to the development of the national industry and promoting the continuous progress of the global health cause.