Oxaliplatin active substance with a very low content of oxalic acid

Abstract

The present invention relates to an oxaliplatin active substance for a pharmaceutical composition, wherein its weight content in oxalic acid is not more than 0.08%, and to a process of preparing the active substance.

1 . Oxaliplatin active substance for a pharmaceutical composition comprising an amount of oxalic acid, characterized by the fact that its weight content in oxalic acid is equal or less than 0.08%.  
     
     
         2 . Active substance of  claim 1  wherein its weight content in oxalic acid is not more than 0.05%, in particular less than 0.02%.  
     
     
         3 . Process of preparing the active substance of  claim 1  or  2  comprising the following steps 
 (a) reacting in aqueous solution potassium tetrachloroplatinate K 2 PtCl 4  with trans-I-1,2-cyclohexanediamine, such as to obtain dichloro(trans-I-1,2-cyclohexanediamine)-platinum (II),  
 (b) adding two equivalents in respect to the compound obtained in (a) of silver nitrate, such as to obtain diaquo(trans-I-1,2-cyclohexanediamine)-platinum (II),  
 (c) optionally adding to the obtained solution potassium iodide or sodium iodide, stirring and adding active carbon under stirring,  
 (d) filtering and adding to the obtained filtrate alkali metal salt of oxalic acid, separating the oxaliplatin crystals formed by filtration and washing 2 to 5 times those crystals with water having a pH 4.5-7.0, and  
 (e) purifying oxaliplatin by recrystallisation wherein the crystals are collected on a filter and washed 2 to 5 times with water having a pH 4.5-7.0, wherein the amount of water used in washing during steps (d) and (e) is sufficient to attain the desired weight content in oxalic acid.