Chromatographic separation of verapamil racemate using a varicol continuous multicolumn process

Abstract

Verapamil is a chiral drug that is marketed in its racemic form, but because of the pharmacological effects due to molecule's chirality, one of the enantiomers is more potent, and the other exhibits different activities of therapeutic interest. The preparative separation of the verapamil enantiomers was performed using a continuous Varicol unit operated on a scale of 1 g/day. Amylose tris(3,5-dimethylphenylcarbamate) functioned as the stationary phase, and n-hexane/isopropanol/ethanol mixtures were used as the mobile phase. Diethylamine was used as the additive. The enantiomeric purities were 93.0% for S-(-)-verapamil and 92.0% for R-(+)-verapamil in the raffinate and extract streams, respectively. The unit provided productivities of 0.18 kg of raffinate per day per kg of adsorbent and 0.20 kg of extract per day per kg of adsorbent when using a feed concentration of 12.5 g L-1.