RADIOIODINATION OF ALGINATE VIA COVALENTLY-BOUND TYROSINAMIDE ALLOWS MONITORING OF ITS FATE IN-VIVO

To monitor the fate of alginate following systemic administration, a m ethod was developed that allowed the covalent incorporation of approxi mately 1 mol% tyrosinamide. The product could be radioiodinated to a h igh specific activity, and was subsequently stable on storage at 4-deg rees-C for 30 days, with very little (less-than-or-equal-to 1%) free [ I-125] iodide released over that period. Twenty-four hours following i ntravenous administration, the low molecular weight fraction (less-tha n-or-equal-to 48,000) of the injected polymer was excreted in the urin e while the larger polymer fraction remained in the circulation and di d not readily accumulate in any of the tissues. Almost all of the dose administered by intraperitoneal injection was transferred from the pe ritoneal cavity to the blood compartment within 24 h, with the low mol ecular weight fraction of the polymer excreted in the urine. Following subcutaneous administration, the majority (approximately 70%) of the injected dose was retained at the site of injection at 24 h.