Adaptation of hard gelatin capsules for oral delivery of aqueous radiopharmaceuticals

PURPOSE: Oral administration of Iodine(−131) (I(−131)) solutions causes high risk of contamination for patients and dispensers. The objective of the study was to adapt hard gelatin capsules (HGCs) for filling with radiopharmaceutical solutions without deformation. METHODS: Polystyrene (PS) internally lining films with different thicknesses were used to protect HGCs. The insulated HGCs were evaluated for their physicochemical characteristics and rupturing time in different dissolution media. HGCs internally lined with PS were examined for withstand loading with different volumes and radioactivities of I(−131) solutions. Radioactivity release was studied in deionized water and acidic media. Quality control of released I(−131) was inspected for radiochemical purities. RESULTS: There was a directly proportion between PS lining thickness and stability of HGCs after filling with 500 μl aqueous methylene blue solution. HGCs internally lined with PS 100 μm thickness withstand deformation for ˃ two months; however showed fast in-vitro rupturing time in different dissolution media. Internally lined HGCs loaded with different volumes and radioactivities of I(−131) solutions resisted for one week without radioactive leakage. Yet, revealed complete release of I(−131) after 20 min in dissolution media with great radiochemical purity. CONCLUSION: The study promises safely I(−131) aqueous solution delivery via adapted HGCs. [Figure: see text]