Edible solid foams as porous substrates for inkjet‐printable pharmaceuticals

Graphical abstract Figure. No Caption available. ABSTRACT The aim of this study was to investigate new porous flexible substrates, i.e., solid foams that would serve as a carrier with a high ink absorption potential for inkjet printable pharmaceuticals. Propranolol hydrochloride was used as a model active pharmaceutical ingredient (API). Pharmaceutically approved and edible cellulose derivatives and gums together with different additives were evaluated as a base for the substrate. Different methods for preparation of a solid foam such as freeze‐drying, vacuum oven drying and drying at room temperature were explored. Only freeze‐drying of the polymeric solutions resulted in the desired porous and flexible, but mechanically stable, soft sponge‐like substrates with hydroxypropyl methylcellulose (HPMC)‐based solid foams being the most suitable for the use in continuous inkjet printing. The plasticized HPMC foams had a superior absorption capacity and fast penetration speed for the different solvents due to the open cell pore structure and higher porosity as compared to nonplasticized additive‐free foams, although, the latter were less hygroscopic. The produced solid foams were well suited for inkjet printing of high volumes of API‐containing ink. The inkjet‐printed API was immediately released from the dosage forms upon contact with the dissolution medium. This work demonstrates that the fabricated solid foams, based on plasticized HPMC, show a great potential as porous carriers in the fabrication of high dose dosage forms by inkjet printing.