Evaluation of different substrates for inkjet printing of rasagiline mesylate

The main goal of the present study was to evaluate applicability of the different model substrates, namely orodispersible films (ODFs), porous copy paper sheets, and water impermeable transparency films (TFs) in preparation of the inkjet-printed drug-delivery systems. Rasagiline mesylate (RM) was used as a low-dose active pharmaceutical ingredient (API). Flexible doses of the drug in a single unit were obtained by printing several subsequent layers on top of the already printed ones, using an off-the-shelf consumer thermal inkjet (TIJ) printer. The produced drug-delivery systems were subjected to microscopic and chemical analysis together with solid-state characterization and content uniformity studies. The results revealed that RM recrystallized on the surface of ODFs and TFs, and the printed crystals were arranged in lines. No drug crystals were detected after printing on the surface of the copy paper due to absorption of the ink into the matrix of the substrate. The best linear correlation between the dose of the drug and the number of the printing layers was obtained for the porous copy paper. The other two substrates showed poor linearity and unacceptable standard deviations of the printed drug substance due to limited absorption of the API ink into the carrier. The shear stress between the substrate, the print head, and the paper feeding rollers caused smearing of the drug that had been surface-deposited during the earlier printing cycles. In conclusion, this study indicates that the edible substrates with absorption properties similar to copy paper are favorable for successful preparation of drug-delivery systems by TIJ printers.