This invention relates to the coating of tablets. It is to be understood that the expression "tablets" as used herein is intended to refer solely to articles having a tablet-like shape which can be tumbled in a coating pan and includes articles having a ball-like, semi-spherical, torpedo-like or other shape. The definition is not restricted to pharmaceutical dosage forms, but may relate to articles coated in the confectionary or other industries.
In the pharmaceutical industry it is well known to provide a core tablet containing a medicament with a sugar coating by tumbling a quantity of core tablets in a pan which rotates about an axis which may be inclined with respect to the horizontal. A coating liquid, which may be a solution or suspension, is applied to the mass of tablets in the pan and as the pan rotates the surface of the tablets become evenly coated by their tumbling action in contact with the coating liquid. The application is then dried in an air stream. In general, a large number of separate applications is necessary before a satisfactory tablet is finally produced and whilst many of these applications are identical, a coating method may also include applications of different volumes or of different coating liquids. A similar technique is used for the manufacture of some sweetmeats.
The coating of tablets in this known way is not easy to control and requires skilled operators giving constant attention, especially when working to the high standards of quality control demanded by the pharmaceutical industry. Hence the process is expensive in terms of time and labour.
An object of the invention is to simplify and standardise the coating of tablets and provide a more efficient coating method in terms of time, resources and quality of finished product as compared with known methods.