Many tablets today are coated after being pressed. Some coatings are just to provide color or a smooth finish, or to facilitate printing on the tablet (although characters and symbols are easy to emboss into the tablets using special punches). Coatings are not often sugar-based (the old "sugar-coating"!) to make pill-taking less unpleasant. Some tablets, however, have a special coating termed an enteric coating, which is resistant to stomach acid and dissolves in the high pH of the intestines. The purpose of this coating is to prevent dissolution of the tablet in the stomach, where the stomach acid may degrade the active ingredient, or where the time of passage may compromise its effectiveness, in favor of dissolution in the small intestine, where the active principle is better absorbed.\n\nTablet presses, the machines that make the tablets, range from small, inexpensive bench-top models that make one tablet at a time, no more than a few thousand an hour, and with only around a half-ton pressure, to large, computerized, industrial models that can make hundreds of thousands of tablets an hour with much greater pressure. Some tablet presses can make extremely large tablets, such as some of the toilet cleaning and deodorizing products.
Can anyone tell me how a tablet(medicine) works?