Ten systems, one brand.

Start from the job the coat has to do rather than from the product list. If the tablet only needs covering and a finish, that is film coating. If the active is destroyed by stomach acid, that is enteric. If the product passes release but drifts on stability, that is a moisture barrier. If it fails on the press rather than in the pan, the answer is an adsorbent and not a coat at all.

An immediate release film only has to form, adhere and look right. An enteric film has to form and then stay impermeable to acid. A bed run warmer than 30 to 32 degrees softens the polymer as it lands, and the film coalesces unevenly. Those weak points are invisible on the tablet and decisive in an acid stage.

Rarely, and the exception proves the rule. UZ1 disperses in either water or solvent, so it spans both film coating routes. Everything else is formulated for one job, because a film optimised for barrier performance is not the film you want when dissolution is the constraint.

Not every one, but under an enteric coat on an acid labile core it is not optional. The seal isolates the core from the enteric polymer and gives the functional film an even surface to build on. On a robust core going under a plain film coat, it is usually unnecessary.

Three of the ten. The taste mask goes into a suspension formulation, the dissolution enhancer and the hygroscopic adsorbent go into the powder before compression. None of them have coating parameters, because nothing is being coated.