Improvement of dissolution rate of indomethacin by inkjet printing.

The aim of this study was to prepare printable inks of the poorly water soluble drug indomethacin (IMC), fabricate printed systems with flexible doses and investigate the effect of ink excipients on the printability, dissolution rate and the solid state properties of the drug. A piezoelectric inkjet printer was used to print 1×1cm(2) squares onto a paper substrate and an impermeable transparency film. l-arginine (ARG) and polyvinylpyrrolidone (PVP) were used as additional formulation excipients. Accurately dosed samples were generated as a result of the ink and droplet formation optimization. Increased dissolution rate was obtained for all formulations. The formulation with IMC and ARG printed on transparency film resulted in a co-amorphous system. The solid state characteristics of the printed drug on porous paper substrates were not possible to determine due to strong interference from the spectra of the carrier substrate. Yet, the samples retained their yellow color after 6months of storage at room temperature and after drying at elevated temperature in a vacuum oven. This suggests that the samples remained either in a dissolved or an amorphous form. Based on the results from this study a formulation guidance for inkjet printing of poorly soluble drugs is also proposed.