Solid dosage forms, such as tablets, have a polymer film coating applied to achieve desired characteristics that otherwise cannot be retained in an uncoated product. They are typically non porous and dense, between 20 and 100 micron thick; some spanning up to 200 micron.
Coatings are produced with different functions in mind. A conventional coating is known as ‘non functional’ but serves as protection, increasing product strength, masks tastes or odours from the core and can improve product aesthetics. Functional coatings are designed to release dosages in accurate and controlled measures. Mainly to prevent the dissolution of product within the stomach to give a more targeted delivery within the intestines.
As a component of film coatings, water must be completely free of particles, ions and other contaminants that could interfere with the products contents. Deionised water is the ideal purity for this application, therefore, deionisation will be staged after reverse osmosis. RO will reduce the salts and ions within the water by around ~99%, which is supplemented by the removal of particles and organic pollutants before this stage. This will leave the required dust free finish, rid of tastes and odours, ready for the coating production.