title: Biodistribution of a radiolabelled thermoresponsive polymer in mice.
abstract: Drug delivery systems based on thermoresponsive polymers might serve as suitable carriers for local radiotherapy. We have, therefore, designed and synthesized a radioiodine-labellable thermoresponsive polymer. The polymer was synthesized by copolymerization of N-isopropylacrylamide with N-methacryloyl tyrosinamide in tetrahydrofuran, and then labelled by (131)I. The solution of this labelled polymer in dimethylsulfoxide (4.4 MBq/ml; 1.8 wt% polymer) was applied to femoral muscle of male Balb/C mice (50 microl per animal). The biodistribution and excretion of radioactivity was followed in 2h and 1, 7, 14, 28 and 42 d post injection (n=6 per time point). As expected, the labelled polymer was left on the application site (ca 90% 2h post injection), decreasing slowly to ca 80% within 14 d. At 28 d post injection, ca 70% of the injected activity was still found on the application site, decreasing to ca 60% at 42 d. No organ-specific accumulation of the radioactivity released from the application site, including thyroid, was observed. Majority of the released radioactivity was excreted via urine and faeces. This preliminary study suggests that thermoresponsive polymers could be used as an effective delivery system for localized radiotherapy.
authors.affiliation: Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, Husinec-Rez 130, Rez, CZ-250 68, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Kucka
authors.forename: Martin
authors.initials: M
authors.lastname: Hrubý
authors.forename: Ondrej
authors.initials: O
authors.lastname: Lebeda
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000180:Acrylic Resins / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000627:therapeutic use*; D000818:Animals; D016503:Drug Delivery Systems / Q000379:methods*; D007457:Iodine Radioisotopes; D008297:Male; D008689:Methacrylates / Q000737:chemistry*; D051379:Mice; D008807:Mice, Inbred BALB C; D018482:Muscle, Skeletal / Q000378:metabolism; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000493:pharmacokinetics / Q000627:therapeutic use; D011878:Radiotherapy / Q000379:methods*; D013696:Temperature; D014018:Tissue Distribution; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D007457:Iodine Radioisotopes; D008689:Methacrylates; C550257:N-methacryloyl tyrosinamide; D019275:Radiopharmaceuticals; D014443:Tyrosine; C067295:N-isopropylacrylamide