Isotope preparation method

Abstract

The present invention provides a method for the generation of 223Ra of pharmaceutically tolerable purity comprising i) preparing a generator mixture comprising 227Ac, 227Th and 223Ra; ii) loading said generator mixture onto a strong base anion exchange resin; iii) eluting said 223Ra from said strong base anion exchange resin using a first mineral acid in an alcoholic aqueous solution to give a first eluted 223Ra solution; iv) loading the 223Ra of the first eluted 223Ra solution onto a strong acid cation exchange resin; and v) eluting the 223Ra from said strong acid cation exchange resin using a second mineral acid in aqueous solution to provide a second eluted solution. The invention additionally provides products of corresponding purity and/or products obtained or obtainable by such a method.

1 . A method for the generation of  223 Ra of pharmaceutically tolerable purity comprising
 i) preparing a generator mixture comprising  227 Ac,  227 Th and  223 Ra;   ii) loading said generator mixture onto a strong base anion exchange resin;   iii) eluting said  223 Ra from said strong base anion exchange resin using a first mineral acid in an alcoholic aqueous solution to give a first eluted  223 Ra solution;   iv) loading the  223 Ra of the first eluted  223 Ra solution onto a strong acid cation exchange resin; and   v) eluting the  223 Ra from said strong acid cation exchange resin using a second mineral acid in aqueous solution to provide a second eluted solution.   
     
     
         2 . The method of  claim 1 , further comprising
 x) eluting said  227 Ac and  227 Th from said strong base anion exchange resin using a third mineral acid in aqueous solution, whereby to provide a mixture of  227 Ac and  227 Th, wherein step occurs at any time following step ii).   
     
     
         3 . The method of  claim 2 , wherein at least 99.9% of the  227 Ac loaded onto the resin in step ii) is recovered in step x). 
     
     
         4 . The method of  claim 2 , wherein at least 98% of the  227 Th loaded onto the resin in step ii) is recovered in step x). 
     
     
         5 . The method of  claim 1 , further comprising
 y) storing said mixture of  227 Ac and  227 Th for a period sufficient to allow ingrowth of  223 Ra by radioactive decay, whereby to regenerate a generator mixture comprising  227 Ac,  227 Th and  223 Ra.   
     
     
         6 . The method of  claim 1 , wherein the method purifies sufficient  223 Ra for more than 10 typical doses. 
     
     
         7 . The method of  claim 1 , wherein a  227 Ac radioactivity of at least 500 MBq is employed in step i). 
     
     
         8 . The method of  claim 1 , wherein the strong base anion exchange resin is a polystyrene/divinyl benzene copolymer based resin. 
     
     
         9 . The method of  claim 1 , wherein the strong base anion exchange resin is an R—N + Me 3  type (type I) resin or an R—N + Me 2 CH 2 CH 2 OH (Type II) resin. 
     
     
         10 . The method of  claim 1 , wherein the first mineral acid is an acid selected from H 2 SO 4  and HNO 3 . 
     
     
         11 . The method of  claim 1 , wherein the first mineral acid is used at a concentration of 0.01 to 5 M. 
     
     
         12 . The method of  claim 1 , wherein the alcoholic aqueous solution comprises at least one alcohol selected from methanol, ethanol and isopropanol. 
     
     
         13 . The method of  claim 1 , wherein the alcoholic aqueous solution comprises 20 to 99% methanol. 
     
     
         14 . The method of  claim 1 , wherein the first eluted solution has a contamination level of no more than 100 Bq  227 Ac per 1 MBq  223 Ra. 
     
     
         15 . The method of  claim 1 , wherein the steps of loading the generator mixture onto the base anion exchange resin and eluting the first eluted  223 Ra solution provide a separation ratio of  223 Ra to  227 Ac of at least 10,000:1. 
     
     
         16 . The method of  claim 1 , wherein the strong acid cation exchange resin is a polystyrene/divinyl benzene copolymer based resin. 
     
     
         17 . The method of  claim 1 , wherein the strong acid cation exchange resin is of SO 3 H type. 
     
     
         18 . The method of  claim 1 , wherein the second mineral acid is an acid selected from H 2 SO 4 , HNO 3  and HCl. 
     
     
         19 . The method of  claim 1 , wherein the second mineral acid is used at a concentration of 0.5 to 5 M. 
     
     
         20 . The method of  claim 1 , wherein the aqueous solution preferably does not comprise any significant amount of any alcohol selected from methanol, ethanol and isopropanol. 
     
     
         21 . The method of  claim 1 , wherein the second eluted solution has a contamination level of no more than 45 Bq  227 Ac per 1 MBq  223 Ra. 
     
     
         22 .  223 Ra comprising less than 45 Bq  227 Ac per 1 MBq  223 Ra. 
     
     
         23 .  223 Ra comprising less than 45 Bq  227 Ac per 1 MBq  223 Ra, formed or formable by a method according to  claim 1 . 
     
     
         24 . A pharmaceutical composition comprising the  223 Ra according to  claim 22 , and at least one pharmaceutically acceptable diluent.