US Patent 7678908 Process of preparing desaloratadine

The present invention provides substantially pure desloratadine having an HPLC purity greater than 99.5% and having an absorbance less than 0.15 Au at 420 nm for a 5% w/v solution in methanol, which does not show a peak for an impurity at a relative retention time in the range from about 0.85 to about 0.99 (relative to desloratadine appearing at a retention time of 25±5 minutes), which is greater than the discard limit set at less than 0.025% of the total area, when tested according to an HPLC method performed using a Hypersil BDS C8 column (15 cm×4.6 mm, 5 μm particle size) with the following parameters: