Purifying actinium-225 from irradiated radium-226 targets, for production of compositions for use e.g. in radioimmunotherapy, involves separation by two-stage extraction chromatography on special coated supports

摘要

A method for purifying 225Ac (I) from irradiated 226Ra (II) targets involves eluting all the (I) and (II) with acid, separating (I) from (II) and other radium isotopes by extraction chromatography using a solid support coated with N,N-dialkylamidomethyl-diorganophosphine oxide in a trialkyl phosphate, and then separating (I) from 210Po and 210Pb by extraction chromatography on a solid support coated with optionally substituted bis-cyclohexano-18-crown-6 in a 4-12C alkanol.. A method (M1) for purifying 225Ac from irradiated 226Ra targets (made on a support) involves (a) eluting the target with nitric or hydrochloric acid under reflux to remove all the 225Ac and 226Ra, (b) removing the HCl (if used) and redissolving the material in nitric acid, (c) concentrating the extract, (d) separating the 225Ac from 226Ra and other radium isotopes by extraction chromatography using a solid support coated with an extraction system comprising compound(s) of formula (I) in compound(s) of formula (II), (e) eluting the retained 225Ac from the stationary phase with dilute nitric or hydrochloric acid ( 226Ra is eluted in stage (d)), (f) separating the 225Ac from 210Po and 210Pb by extraction chromatography using a solid support coated with an extraction system comprising compound(s) of formula (III) in compound(s) of formula R 10-OH (IV), (g) using 2M-HCl as mobile phase and (h) recovering 225Ac from the eluate, the 210Po and 210Pb being retained on the solid support. R1, R2 : octyl, n-octyl, phenyl or (1-3C alkyl)-substituted phenyl; R3, R4 : n- or iso-propyl, or n- or iso-butyl; R5-R7 : 2-5C alkyl, preferably n- or iso-butyl; R8, R9 : H, 1-5C alkyl or tert.-butyl; R10 : 4-12C alkyl. Independent claims are included for (1) a method (M2) for purifying 225Ac as above, in which the solid support in stage (d) is coated with compound(s) of formula (IA) and stage (e) involves elution with 0.3-0.01M nitric acid or 1-0.05M hydrochloric acid (2) a method (M3) as above in which the support in (d) is coated with compound(s) of formula (IB) and stage (e) involves elution with 0.02-0.1M nitric acid (3) pharmaceutically-acceptable radionuclide compositions containing 225Ac and obtained by the above methods. R1a-R4a : octyl or 2-ethylhexyl. ACTIVITY : Cytostatic. No biological data given. MECHANISM OF ACTION : None given.