An edible product such as a unit
dosage form of a pharmaceutically active substance includes a layer of a material that can receive and retain a
high resolution microrelief that can convey information. The microrelief is themo-formable, preferably formed from an
aqueous solution of HPMC and / or HPC plus a
plasticizer and colorant. Other additives such as strengtheners, surfactants and adherents may be used depending on the application. The materials are selected and proportioned to control the
fading or change in color of the visual image or effect produced by the relief to indicate
exposure to an unacceptable degree of heat or
humidity. The
dosage form can be the relief-containing layer itself with the pharmaceutical carried therein. In a preferred form, the layer is an outer
coating over a core containing the pharmaceutically active substance.
Coated tablets are configured to
resist twinning. To produce such dosage forms, the coated core is transported in
unison with a flexible mold or transfer plate that can heat-replicate the microrelief on the outer layer of the
dosage form, followed by a cooling and release of the transfer plate from the
coating.