Portable semisolid extrusion device for the production of personalized medicines in diverse settings

The potential of 3D printing (3DP) in personalized medicine has led to the development of various pharmaceutical-grade printers, advancing its integration into clinical practice. However, accessible and decentralized solutions are still required to enable on-demand drug production in remote or resource-limited settings. Handheld 3D pens offer a compact, portable, and energy-efficient alternative, particularly suited for small pharmacies, mobile clinics, emergency operations, and underserved regions. This study presents the first application of a handheld 3D pen using semisolid extrusion (SSE) technology for the precise fabrication of citrulline lozenges (200-700 mg). Citrulline, an amino acid used in the treatment of rare diseases, was formulated into two pharma-ink bars containing 30 % and 50 % w/w citrulline. Minimal materials were used, with isomalt, a sugar substitute, as the main excipient along with water, and no organic solvents were involved. Dose personalization was evaluated by selecting the printed area and the printing time, with a strong correlation observed between printing time and final dose. The printed lozenges exhibited excellent dose accuracy and recovery (∼100 %), while dissolution tests reported an 80 % of citrulline released within the first 12 min. The pharma-ink bars remained stable over one month, exhibiting minimal water loss (∼2%) and retaining both printability and drug integrity. These findings establish handheld 3D pens as environmentally-friendly technology for rapid personalized drug manufacturing. The combination of stable pharma-inks and precise dose control underscores its potential for decentralized, on-demand production of personalized therapies in remote and resource-constrained environments.