Purpose of Coating: Coating is like a cover of core tablets. To protect the tablet from light, moisture, temperature and finally for the elegance of the product. Coating of a tablet using powdered granule. It is prepared by feeding previously compressed tablets in to a special machine and compressing another granulation layer around the preformed tablets. Oral tablet coated with a sugar or film coating. The purpose of coating are-
i) To mask bitter and unpleasant taste and odor and color of the drug
ii) To overcome stomach or Gastric irritation
iii) To overcome decomposition of the drug
iv) To maintain prolong action
v) To make tablets shape smooth
vi) Improved esthetic qualities of the product
vii) Enabling the product to more easily swallowed by the patient and improving product stability.
viii) To provide physical and chemical protection for the drug.
ix) To incorporate another drug or formula adjuvant in the coating to avoid chemical incompatibilities or the provide sequential drug release.
x) Modifying drug release characteristics and to improve the pharmaceutical elegance by use of special colors and contrasting printing.