Hygroscopicity of a sugarless coating layer formed by the interaction between mannitol and poly(vinyl alcohol) (PVA)

- The sugarless-coating solution comprising PVA and D-mannitol was applied to tablets by a continuous spray method.
- The hygroscopicity of the sugarless layer has the lowest at concentration ratios between 15:2.5 and 15:4 (w/w) of mannitol and PVA.
- The surface state of the sugarless layer exhibits the smoothest surface at a mannitol:PVA concentration ratio between 15:2.5 and 15:4 (w/w).
- The surface states of the sugarless-layer-coated tablets are related to the molecular motions of mannitol in the sugarless layer.