Optimising 3D printed medications for rare diseases: In-line mass uniformity testing in direct powder extrusion 3D printing.

Biotinidase deficiency is a rare inherited disorder characterized by biotin metabolism issues, leading to neurological and cutaneous symptoms that can be alleviated through biotin administration. Three-dimensional (3D) printing (3DP) offers potential for personalized medicine production for rare diseases, due to its flexibility in designing dosage forms and controlling release profiles. For such point-of-care applications, rigorous quality control (QC) measures are essential to ensure precise dosing, optimal performance, and product safety, especially for low personalized doses in preclinical and clinical studies. In this work, we addressed QC challenges by integrating a precision balance into a direct powder extrusion pharmaceutical 3D printer (M3DIMAKER™) for real-time, in-line mass uniformity testing, a critical quality control step. Small and large capsule-shaped biotin printlets (3D printed tablets) for immediate- and extended-release were printed. The integrated balance monitored and registered each printlet's weight, identifying any deviations from acceptable limits. While all large printlet batches met mass uniformity criteria, some small printlet batches exhibited weight deviations. In vitro release studies showed large immediate-release printlets releasing 82% of biotin within 45 min, compared to 100% for small immediate-release printlets. For extended-release formulations, 35% of the drug was released from small printlets, whereas 24% was released from large printlets at the same time point. The integration of process analytical technology tools in 3DP shows promise in enhancing QC and scalability of personalized dosing at the point-of-care, demonstrating successful integration of a balance into a direct powder extrusion 3D printer for in-line mass uniformity testing across different sizes of capsule-shaped printlets.