The present invention relates to optically pure S-(-)-benzoquinolizine carboxylic acids, their derivatives, salts, pseudopolymorphs, polymorphs and hydrates thereof, substantially free of their R-(+)-isomers, to processes for preparation of the optically pure S-(-)-benzoquinolizine carboxylic acids, their derivatives, salts, pseudopolymorphs, polymorphs and hydrates thereof substantially free of their R-(+)-isomers, and to pharmaceutical compositions comprising the S(-)-benzoquinolizine carboxylic acids, their derivatives, salts, pseudopolymorphs, polymorphs and hydrates thereof.