Colorimetry as Quality Control Tool for Individual Inkjet-Printed Pediatric Formulations

Printing technologies were recently introduced to the pharmaceutical field for manufacturing of drug delivery systems. Printing allows on demand manufacturing of flexible pharmaceutical doses in a personalized manner, which is critical for a successful and safe treatment of patient populations with specific needs, such as children and the elderly, and patients facing multimorbidity. Printing of pharmaceuticals as technique generates new demands on the quality control procedures. For example, rapid quality control is needed as the printing can be done on demand and at the point of care. This study evaluated the potential use of a handheld colorimetry device for quality control of printed doses of vitamin Bs on edible rice and sugar substrates. The structural features of the substrates with and without ink were also compared. A multicomponent ink formulation with vitamin B₁, B₂, B₃, and B₆ was developed. Doses (4 cm²) were prepared by applying 1–10 layers of yellow ink onto the white substrates using thermal inkjet technology. The colorimetric method was seen to be viable in detecting doses up to the 5th and 6th printed layers until color saturation of the yellow color parameter (b*) was observed on the substrates. Liquid chromatography mass spectrometry was used as a reference method for the colorimetry measurements plotted against the number of printed layers. It was concluded that colorimetry could be used as a quality control tool for detection of different doses. However, optimization of the color addition needs to be done to avoid color saturation within the planned dose interval.