Pharmaceutical compositions containing lanthanum hydroxycarbonate

Abstract

An assay for analytically determining the amount of an impurity in a solid sample is provided. This X-ray diffraction method preferably uses the Rietveld refinement.

1 - 15 . (canceled) 
   
   
       16 . A pharmaceutical composition comprising lanthanum hydroxycarbonate form (I) characterized by an X-ray powder diffraction pattern having peaks at approximately 17.7°, 24.4°, and 30.3° two theta, wherein the lanthanum hydroxycarbonate content of the composition comprises at least 96% lanthanum hydroxycarbonate form (I). 
   
   
       17 . The pharmaceutical composition of  claim 16 , wherein the lanthanum hydroxycarbonate content of the composition comprises at least 98% lanthanum hydroxycarbonate form (I). 
   
   
       18 . The pharmaceutical composition of  claim 17 , wherein the lanthanum hydroxycarbonate content of the composition comprises at least 99% lanthanum hydroxycarbonate form (I). 
   
   
       19 . The pharmaceutical composition of  claim 16 , further comprising lanthanum carbonate. 
   
   
       20 . The pharmaceutical composition of  claim 19 , further comprising lanthanum carbonate tetrahydrate. 
   
   
       21 . The pharmaceutical composition of  claim 19 , further comprising lanthanum carbonate octahydrate. 
   
   
       22 . A composition comprising lanthanum carbonate and from 0.88% to 31.01% of lanthanum hydroxycarbonate, based upon the total amount of lanthanum carbonate and lanthanum hydroxycarbonate in the composition. 
   
   
       23 . The composition of  claim 22 , wherein the composition comprises from 1% to 31.01% of lanthanum hydroxycarbonate form (II), based upon the total amount of lanthanum carbonate and lanthanum hydroxycarbonate in the composition. 
   
   
       24 . The composition of  claim 22 , wherein the composition comprises from 3.74% to 31.01% of lanthanum hydroxycarbonate, based upon the total amount of lanthanum carbonate and lanthanum hydroxycarbonate in the composition. 
   
   
       25 . The composition of  claim 22 , wherein the composition comprises from 1.74% to 29.9% of lanthanum hydroxycarbonate form (I), based upon the total amount of lanthanum carbonate and lanthanum hydroxycarbonate in the composition. 
   
   
       26 . A composition comprising (a) lanthanum carbonate tetrahydrate, (b) lanthanum carbonate octahydrate, and (c) (i) lanthanum hydroxycarbonate form (I) characterized by an X-ray powder diffraction pattern having peaks at approximately 17.7°, 24.4°, and 30.3° two theta. 
   
   
       27 . The composition of  claim 26 , further comprising lanthanum hydroxycarbonate form (II).