Effects of Eppikahangeto, a Kampo Formula, and Ephedrae herba Against Citric Acid-Induced Laryngeal Cough in Guinea Pigs

Abstract

Abstract.: To evaluate the efficacy of three common antitussive Kampo formulas, eppikahangeto (EPP), bakumondoto (BAK), and shoseiryutogomakyokansekito (SGM), a new cough model of guinea pig was used, which could specifically induce a laryngeal cough by microinjection of citric acid solution into the larynx. Kampo extract was dissolved in water and the animals were given access ad libitum for 3 days, and then the number of coughs during 10 min was counted. EPP extract decreased the number of coughs dose-dependently (0.3% extract, −22.9 ± 6.6%, P<0.01; 1.0% extract, −32.4 ± 5.5%, P<0.01). BAK extract and SGM extract had no significant effect. Intraperitoneal injection of codeine (60 mg/kg) also decreased the number of coughs (−36.1 ± 9.1%, P<0.05). Furthermore, Ephedrae herba (EH) extract reduced the number of coughs (−18.3 ± 6.0%, P<0.05), but the extract of EPP without EH did not. These results suggest that EPP has an antitussive effect against laryngeally-induced cough in guinea pigs, and the crucial herbal medicine is EH. Keywords:: Kampo medicine, eppikahangeto, Ephedrae herba, antitussive effect, laryngeal cough