Antitussive effect of moguisteine on the enhanced coughing associated with enalapril in guinea-pig.

The effect of moguisteine, a novel peripherally acting non-narcotic antitussive drug, on coughs associated with enalapril was examined in guinea-pigs. Chronic treatment with enalapril markedly enhanced the number of capsaicin-induced coughs. Moguisteine dose-dependently suppressed the number of coughs at doses between 3-30 mg/kg p.o., in both vehicle-treated and enalapril-treated animals. There was no significant difference in the antitussive ED50 (95% confidence limit) value of moguisteine between vehicle-treated (16.4 (13.7-19.7) mg/kg) and enalapril-treated (13.7 (3.9-47.6) mg/kg) animals. On the other hand, dihydrocodeine also dose-dependently suppressed the number of coughs in the same dose range as moguisteine in both vehicle-treated and enalapril-treated animals. There was no significant difference in the antitussive ED50 (95% confidence limit) of dihydrocodeine between vehicle-treated (11.7 (4.9-28.3) mg/kg) and enalapril-treated (11.2 (9.4-13.3) mg/kg) animals. Furthermore, the antitussive effect of moguisteine was identical to that of dihydrocodeine in both vehicle-treated and enalapril-treated animals. On the other hand, while chronic co-treatment with moguisteine significantly reduced the number of enhanced coughs associated with enalapril, chronic co-treatment with dihydrocodeine had no significant effect on the number of enhanced coughs associated with enalapril treatment. These results suggest that moguisteine may have a therapeutical benefit in reducing the coughing associated with treatment with inhibitors of angiotensin-converting enzyme.