Physicochemical characterization and clinical evaluation of 3D-printed subdivided tablets of 6-Mercaptopurine with broad dosage variations.

6-Mercaptopurine (6-MP), a first-line drug for the maintenance treatment of acute lymphoblastic leukemia (ALL) in pediatric patients, has an extremely narrow therapeutic window and exhibits considerable dosage variability. This study employed semi-solid extrusion (SSE) 3D printing to fabricate precisely dosed subdivided 6-MP tablets of 1, 3, 5, 15, and 20 mg using two formulations (low-dose and high-dose). Printability-guided optimization was conducted to identify the optimal formulations. The low-dose formulation comprised commercial 6-MP powder, 10% hydroxypropyl methylcellulose (HPMC) hydroalcoholic gel, and a 6:7 (w/w) mixture of cornstarch and microcrystalline cellulose, whereas the high-dose formulation consisted of commercial 6-MP powder, 10% HPMC hydroalcoholic gel, 2% magnesium stearate, and 3% sodium carboxymethyl starch. All five dosage specifications met pharmacopoeial standards for mass uniformity, drug content, content uniformity, and dissolution. High-performance liquid chromatography, powder X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy were employed to analyze the physicochemical characterization of 6-MP before and after 3D printing, confirming that the drug content, crystal form, and chemical structure of 6-MP remained unchanged during SSE 3D printing and 7-day storage. Pediatric patients with ALL were treated with either 3D-printed or pharmacist-splitting group subdivided 6-MP doses. Paired t-tests within each group revealed significant differences in white blood cell counts pre-treatment and post-treatment (pharmacist-splitting group: P < 0.01; 3D-printed group: P < 0.001), indicating that both groups exhibited pharmacological activity, with the 3D-printed group achieving improved control of hematological indices. Overall, SSE 3D printing technology enables accurate and safe individualized drug dosing.