APPLICATIONS OF SIMULATED MOVING-BED CHROMATOGRAPHY TO THE SEPARATIONOF THE ENANTIOMERS OF CHIRAL DRUGS

Although most preparative chiral separations have been performed in th e conventional batch-mode process, interest in simulated moving-bed (S MB) chromatography is growing, because it permits large amounts of mob ile phase to be saved and productivity increased, thus reducing produc tion costs. Based on the examples of three different drugs, the useful ness of this technique for the separation of enantiomers on a preparat ive scale has been demonstrated. Compared to the batch elution chromat ography, a reduction of the mobile phase consumption of respectively 8 1% and 84% has been achieved for the separation of the enantiomers of the antiasthmatic agent formoterol and of the antitussive agent guaife nesin. Furthermore, a higher throughput could be reached under SMB con ditions. The influence of feed rate and extract on the separation has also been investigated. The results show that these two factors consid erably affect purity and productivity, and constitute important parame ters for finely adjusting the chromatographic conditions depending on the requirements. For all racemates, both enantiomers could be obtaine d with a purity ranging between 99 and 99.9%.