Evaluation of the Antitussive and Analgesic Activities of Peperomia pellucida Whole Plant Methanol Extract in Rodents

Background and Purpose: Peperomia pellucida (Piperaceae) is a plant used in ethnomedicine to treat asthma, colds, coughs, and other illnesses. This study aimed to evaluate the antitussive, expectorant, and analgesic activities of a 70% methanol extract of the plant. Methods: Citric acid and ammonia-induced rodent cough models; and phenol red dye expectorant models in mice were used to evaluate the antitussive and expectorant properties of the orally administered extract. The hot plate and acetic acid-induced mouse writhing models were used to evaluate analgesia. Results: Dihydrocodeine (25 mg/kg); and 100, 200, and 400 mg/kg of the extract significantly reduced the frequency of cough bouts and increased the percentage suppression of cough-in citric acid and ammonium hydroxide-induced cough models compared with control (P<0.05, P<0.01, P<0.001). Bromhexine (15 mg/kg); 100 and 400 mg/kg of the extract increased the secretion of phenol red dye in mice when compared with the control (P<0.05, P<0.01). Doses of the extract (100, 200 mg/kg) and pentazocine (3 mg/kg) increased (P<0.05) the latency to response time in hot plate-induced pain. At 400 mg/kg, the extract; and acetylsalicylic acid (100 mg/kg) reduced the number of writhing and increased the percentage inhibition of pain in the acetic acid-induced model when compared to the control (P<0.05, P<0.001). Conclusion: The 70% methanol extract of P. pellucida possesses antitussive, expectorant, and analgesic activities in rodents.