Development and Evaluation of 3D Printed Allopurinol Tablets for Veterinary Use

Purpose Canine leishmaniasis is one of the most important endemic zoonotic diseases in Latin America, affecting thousands of individuals. Treatment in dogs commonly involves the use of agents with leishmanicidal activity such as allopurinol, typically administered in combination with miltefosine or meglumine antimoniate. Long-term management frequently relies on the off-label use of human formulations (100 or 300 mg tablets), requiring tablet splitting to achieve dose adjustment for infected dogs, which may compromise dosing accuracy. Methods To address this limitation, allopurinol printlets were developed using semi-solid extrusion (SSE) 3D printing (ALLO-3D) to enable dose personalization for small- to medium-sized dogs. The drug dissolution and release kinetics of the printlets were investigated. The greenness profile of the 3D printing was evaluated using the Index of Greenness Assessment of Printed Pharmaceuticals (iGAPP). Results The optimized formulation, composed of hydroxypropyl methylcellulose (HPMC), lactose monohydrate, croscarmellose sodium (CCS-Na), and a water–ethanol (7:3, v/v) binder solution, exhibited an immediate-release profile (Q = 75%; 45 min). The developed printlets showed a mean weight of 390.1 mg (RSD = 1.65), drug content of 39.83 ± 0.75 mg printlet⁻¹, and content uniformity of 104.74 ± 2.36% (AV = 5.4). All quality control tests complied with the requirements established in the official codes for oral solid dosage forms. The drug release profile was best described by the First-order model (R² > 0.95). Conclusion These findings demonstrate that SSE 3D printing represents a promising strategy to produce personalized printlets containing allopurinol, enabling accurate dose adjustment and potentially improving therapeutic management in canine leishmaniasis. Additionally, the ALLO-3D manufacturing process proved to be suitable from an environmental impact perspective according to the iGAPP metric.