Preparation and evaluation of radiolabeled acetaminosalol microspheres: A new potential selective radiotracer for ulcerative colitis early diagnosis.

Acetaminosalol labeling reaction with technetium-99m was optimized, and the radiocomplex was obtained in a high radiochemical yield of 98.9 ± 0.6% and high stability (>30 h). The tracer was characterized, and its binding to the PPARγ receptor was assessed in silico. To reduce radiation exposure to non-target organs and increase accumulation in the colon, the tracer was formulated as pH-sensitive microspheres with a mean particle size of 201 ± 2.1 μm, a polydispersity index of 0.18, a 25.3 ± 3.6 zeta potential, and 98.6 ± 0.33% entrapment efficiency. The system suitability was assessed in vivo in normal and ulcerative rats, and the biodistribution profile in the colon showed 56.5 ± 1.4% localization within 4 h. Blocking study suggested the selectivity of the tracer to the target receptor. Overall, the reported data encouraged the potential use of the labeled microspheres to target ulcerative colitis.