Neutron-activated holmium-166-poly (L-lactic acid) microspheres: a potential agent for the internal radiation therapy of hepatic tumors.
Biodegradable Poly(L-lactic acid) microspheres containing neutron-activable 165Ho were designed for internal radiation therapy of hepatic tumors. Spheres composed of Poly(L-lactic acid) (PLA) were prepared with excellent reproducibility containing up to 36% of a holmium complex. The prepared spheres were irradiated in a high neutron flux converting 165Ho to 166Ho (Emax = 1.84 MeV, half-life = 26.9 hr). Thus, these microspheres can be prepared under conditions that do not require the handling of a hazardous radionuclide, and then irradiated just prior to administration. In vitro studies in plasma (n = 6) revealed 97.3% (+/- 1.9) retention of 166Ho in the microspheres after 240 hr. PLA spheres administered via the portal vein in rabbits (n = 6) show 94.5% (+/- 3.4) retention of the original 166Ho activity in the liver after 6 days.
Division of Medicinal Chemistry and Pharmaceutics, College of Pharmacy, University of Kentucky, Lexington 40536-0082.
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D000818:Animals; D001673:Biodegradation, Environmental; D001918:Brachytherapy / Q000379:methods*; D006695:Holmium / Q000627:therapeutic use*; D007773:Lactates; D019344:Lactic Acid; D008114:Liver Neoplasms, Experimental / Q000532:radiotherapy*; D008863:Microspheres; D009502:Neutrons; D011091:Polyesters; D011108:Polymers; D011817:Rabbits; D011868:Radioisotopes / Q000627:therapeutic use*
D007773:Lactates; D011091:Polyesters; D011108:Polymers; D011868:Radioisotopes; D019344:Lactic Acid; C033616:poly(lactide); D006695:Holmium