Two-piece hard gelatine capsules are one of the major pharmaceutical oral dosage forms.
The manufacturing process of hard capsules consists in dipping stainless steel forms called “pins” into a gelatine solution (~30% solution). Once removed from the gelatine solution, the uniform gelatine film that has formed on the pins gels. A drying step allows to obtain dried thin film (capsule walls) showing the adequate mechanical resistance. Capsules are then stripped from the pins and cut. The body and cap are assembled and sorted for obtained pre-locked empty hard gelatine capsules.
The key features of gelatine in this application are:
• A workable viscosity at high concentration allowing high machinability
• A gelling power forming thermo-reversible gel
• A low and suitable setting point
• A film-forming power forming the capsules walls
• High clarity and brightness