Figure 3: Effects of naloxone (3 mg/kg) on the antitussive effects of cod (codeine 10 mg/kg), dex (dextromethorphan 10 mg/kg), and Tc 250 (ethyl acetate fraction of Terminalia chebula 250 mg) and Tc 500 (ethyl acetate fraction of Terminalia chebula 500 mg). Naloxone was injected s.c. 10 min before cough challenge. Codeine and dextromethorphan were injected i.p. 30 min while testing materials were administered i.p. 60 min before cough challenge in mice. Each column represents mean with SEM for at least 8 mice. Significant differences from saline control were indicated as * and ** by Student’s -test.