[Antitussive and expectorant effects of Asada-ame extract]

Asada-ame containing Platycodi Radix, Ginseng Radix, Ephedrae Herba and Ipecacuanhae Radix extracts has been hitherto widely used as an antitussive and expectorant. In the present study, the antitussive effect and tracheo-bronchial secretory activity of Asada-ame extract (AE) were investigated with laboratory animals. Antitussive effect was evaluated with the puncture electrode-induced cough method in conscious guinea pigs. AE showed a significant antitussive effect which lasted more than one hr. 50% Antitussive doses were 76 mg/kg, i.p., and 500 mg/kg, p.o. Airway secretory effect was evaluated with the stopper method in anesthetized dogs. With oral administration of AE, the volume of respiratory tract fluid (RTF) increased, and viscosity of RTF, which was determined using the glass plate method, was decreased in a dose-dependent manner. The effects of AE on secretory activity of canine tracheal secretory cells were investigated in vitro with the histological/histochemical technique. With AE treatment, the thickness of the acini of submucosal glands was decreased, and the ratio of acinar inner diameter of the gland to tracheal wall was increased. Furthermore, the number of acid glycoprotein-containing submucosal glandular cells was decreased by AE, suggesting a mucolytic effect of AE. The above findings indicate that AE has significant antitussive and expectorant effects.