RESUMEN
PURPOSE: This study aims to investigate the additive effect of the Hedera helix (HH) and Rhizoma coptidis (RC) extracts mixture on antitussive and expectorant activities in animals. MATERIALS AND METHODS: The expectorant assay was performed with phenol red secretion in mice trachea. Mice or guinea pigs were randomly divided into groups of 8 each, including negative and positive control groups. After gastric administration of the test extracts in mice, 2.5% phenol red solution (0.2 mL) was intraperitoneally injected. Trachea was dissected and optical density of tracheal secretion was measured. After gastric administration of the test extracts in guinea pigs, the antitussive activities were assessed using a citric acid-induced cough measurement. RESULTS: The extracts of HH and RC significantly increased tracheal secretion and inhibited cough. The mixture of HH and RC extracts in a 1:1 concentration at a dose of 200 mg/kg showed a more potent effect on phenol red secretion (25.25+/-3.14) and cough inhibition (61.25+/-5.36) than the individual use of each extracts [phenol red secretion; HH 13.39+/-4.22 (p=0.000), RC 20.78+/-2.50 (p=0.010), cough inhibition; HH 9.89+/-4.14 (p=0.010), RC 30.25+/-7.69 (p=0.000)]. A 3:1 ratio mixture of HH to RC demonstrated an optimal expectorant effect (p<0.001), and this mixture showed expectorant and antitussive effects in a dose-dependent manner. CONCLUSION: This study provides evidence for antitussive and expectorant effect of a 3:1 mixture of HH and RC, which may be a useful therapeutic option for respiratory diseases.