Synthesis and pharmacological screening of new phenylpiperazinepropane derivatives and their enantiomers.

Enantiomers of phenylpiperazinepropane-1,2-diol derivatives were synthesized with the purpose to obtain a better antitussive activity/sedative effect ratio. (S)-isomers showed better pharmacological profiles than (R)-isomers and corresponding racemates. Among the (S)-isomers, the unsubstituted compound, levodropropizine (S(-)-3-(4-phenyl-piperazin-1-yl)-propane-1,2-diol, DF 526), has the most favourable antitussive activity/sedative effect ratio and was selected for pharmaco-toxicological evaluation.