Tablets remain the most common solid oral dosage form for many reasons, including ease of manufacture, convenience for the patient, accurate dose administration and good stability. Good tablet design can be used to provide product differentiation, avoid medication mix-ups and deter counterfeiting. It can also impact patient compliance.
So, what are the reasons for including a coating on an oral solid dosage form? Purely from an aesthetic point of view, uncoated tablets are undistinguished. In addition, a rough-looking tablet can appear to be of poor quality; not an attribute you want, especially in a medicine.
From the patient’s perspective, coating makes the tablet appear easier to swallow and aids in visual differentiation, thus reducing the potential risk of medication errors. Coating also reduces tablet friability and overcomes any damage or dusting issues often associated with uncoated tablets.
References
http://www.epmmagazine.com/opinion/coating-compliance-—-looking-at-the-important-considerations/