Antitussive Activity of Moguisteine Enantiomers in Guinea-pigs and Rats

Abstract

Abstract The antitussive effect of the R-(+)- and S-(-)-enantiomers of moguisteine were evaluated in comparison with the racemate in cough induced by 7ṁ5% 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: 20ṁ4 (12ṁ9−26ṁ6), 20ṁ9 (14ṁ9−26) and 21ṁ6 (11ṁ8−30ṁ0) mg kg−1 in cough provoked by citric acid and 17ṁ7 (12ṁ5−29ṁ8), 18ṁ9 (14ṁ1−30ṁ1) and 20ṁ5 (15ṁ1−36ṁ6) 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.