Tablet Coater

To describe the procedure for validation of the tablet coater to ensure that it meets installation, operational, and performance qualification requirements 

It is the responsibility of the production manager and technical services manager to follow the procedure. The quality assurance manager is responsible for SOP compliance. 

Instruments for measuring time, temperature, pressure, pressure differences, revolution speed, flow rate, air volume, and converters, as well as recording devices for these variables, should be calibrated. 

Determine the achievable air volume flow (mVh) for the empty and the loaded coater and compare the results with the previous set requirements and the supplier specification. 

3 Delay time for achieving constant inlet air conditions 

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There are as many variations in coating procedures as there are tablet coaters, and so the account given here is only a guide. Nevertheless, it illustrates the complexity and time-consuming nature of the process, and the reader will realize why efforts have been made to develop alternate coatings, equipment, and methods that permit at least some degree of automation. 

Staniforth JN, Reeves LA, Page T. Electrostatic powder coating of tablets I design and characteristics of a continuous coater prototype. Proceedings of the 13th Annual Meeting Exposition of AAPS, San Francisco, 1998. 

Coater load What is the acceptable tablet load range of the equipment Having too large a pan load could cause attrition of the tablets because of the overall tablet weight in the coater. In the case of a fluid bed coater, there may not be sufficient airflow to fluidize the tablets. 

Tablet flow The flow or movement of the tablets in the coater should be examined to ensure proper flow. There should be sufficient tablet bed movement to ensure even distribution of the coating solution onto the tablets. The addition of baffles may be required to provide adequate movement of tablets for tablet coating.

The second approach to coating scale-up involves an understanding of thermodynamic and mass transfer processes. A robust process can be demonstrated by establishing a coating procedure that identifies critical process parameters and their effect on the equilibrium between mass flow (the coating solids applied) and heat transfer (the solvent removed). This approach allows one to evaluate air temperature, air flow, and spray rate as applied to a known mass of tablets, and then scale these conditions into a larger coater. A thermodynamic model for aqueous film coating as described by Ebey is shown in Eq. (9). 

The equation will not always predict actual coating conditions. In this instance, tablet cores were coated in a partially perforated pan that limits the air volume passing through the tablet bed. A correction factor can be added to the model based on the partial perforation and metal mass of the pan. Ende and Berchielli have evaluated several coating pans and have included a heat loss factor in their calculations that relates the heat transfer coefficient and pan surface area. Their model is able to predict exhaust temperature in dissimilar coaters. 

Poloxamers are used as emulsifying agents for intravenous fat emulsions, as solubilising agents to maintain clarity in elixirs and syrups, and as wetting agents for antibacterials. They may also be used in ointment or suppository bases and as tablet binders or coaters. 

Figure 374. Schematic representations of three different configurations of Wurster coaters for use in coating (a) tablets, (b) coarse granules, and (c) fine powders ...

The above method is suitable for the coating of smaller particles, down to 0.1 mm. However, more commonly, small particles, either powders, crystals, or agglomerates, the shape of which may be irregular, spheroidal, tabletted, or spheronized, are typically coated in specially designed fluid bed equipment (see also Section 7.4.4). As with all other coaters, the heart of fluid bed processes is the type and location of the delivery... 

Fig. 6.2-85 Sketches of the different chamber configurations of single tube Wurster coaters as used for a) tablets, b) coarse granules, c) fine particles [B.48]...

Raman and Gray (1994) layered PST, glycerin, and a wax and surfactant blend onto nonpareil seeds in three passes using a fluid-bed coater. These were then compressed into tablets. The in vitro dissolution results indicated some delayed release. 

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