Antitussive activity of moguisteine enantiomers in guinea-pigs and rats.

The antitussive effect of the R-(+)- and S-(-)-enantiomers of moguisteine were evaluated in comparison with the racemate in cough induced by 7m5% citric acid and 30 μM capsaicin aerosol in conscious guinea-pigs. No difference in potency was observed between moguisteine and the enantiomers. The oral ED50 values (with 95% confidence limits) for moguisteine, R-(+)- and S-(-)-enantiomers were respectively: 20m4 (12m9−26m6), 20m9 (14m9−26) and 21m6 (11m8−30m0) mg kg−1 in cough provoked by citric acid and 17m7 (12m5−29m8), 18m9 (14m1−30m1) and 20m5 (15m1−36m6) mg kg−1 in cough induced by capsaicin. The acute oral and intraperitoneal toxicities of the enantiomers and moguisteine in the rat are very similar. These findings suggest that the use of either enantiomer does not offer any advantage over the racemate.