| Description |
Because of the short biological retention half-time of Zn-DTPA and the desirability of a maintained blood level of the chelate, alternative modes of its administration were explored. Zn-DTPA labeled with 65Zn was dried and ground to a fine powder and incorporated into implants of various combinations of cholesterol, polyethylene glycol 4000, beeswax, and peanut oil in order to produce a slow release of the chelation agent. One group of pellets, placed subcutaneously in the dorsal neck of young adult beagles, produced daily release rates of from 0.5% to 41% of the implanted DTPA, increasing with the percentage of polyethylene glycol 4000 in the pellet. When 241Am citrate was injected intravenously into beagles preimplanted with a DTPA pellet, the fraction of the injected 241Am excreted in the first 24 hours increased from 9% (control) to 38% (2.9 umole DTPA/kg/day) to 84% (70 umole/kg/day). [Supported by USERDA; Contract E (11-1)-119.] |
