Polymer encapsulation of indium-111 chloride enabled successful radiolabeling of a large, swelling gastric retentive formulation for gamma scintigraphy evaluation in vitro, preclinically and clinically. The PEIC radiolabel overcame the challenges of premature radiotracer loss in acidic gastric conditions, which compromised assessment with conventional labeling techniques. Enhanced radiolabel retention was achieved by adsorbing indium-111 chloride onto activated charcoal particles and then coating with cellulose acetate polymer, followed by milling to form microparticles that were incorporated into the GRF matrix. This method can potentially improve assessment of gastric retention for other novel oral dosage forms using gamma scintigraphy.
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