STUDIES ON THE ANTITUSSIVE AND SEDATIVE ACTIVITIES OF PEIMINE AND PEIMININE

The antitussive and sedative activities of peimine and peiminine, two alkaloids isolated from Fritillaria verticillata Willd var thunbergii Bak, were investigated in laboratory.The EDT₅₀ (the time needed to make 50% mice cough) was prolonged to 130% of the control when peimine or peiminine 4 mg/kg was administered orally to mice induced to cough by atomized ammonium hydroxide. A 45% inhibition rate of cough amplitude was observed in anesthetized guinea pig induced to cough by stimulation of the mucosa at the tracheal bifurcation with a bristle after a sc injection of peimine or peiminine 4 mg/kg. Peak action appeared 30～60 minutes after the injection. In cats, induced to cough by electrical stimulation at the central stump of the superior laryngeal nerve, both the incidence and amplitude of cough reflex were inhibited by sc injection of 4 mg/kg of peimine or peiminine. The action lasted for an hour or so.The spontaneous activities of mice were significantly decreased by peimine or peiminine after sc injection of a dose of 2 mg/kg. Furthermore, the CNS stimulating action of caffeine was antagonized and the sedative action of chlorpromazine was potentiated by peimine and peiminine in mice at the same dose level. It appears that both peimine and peiminine have antitussive and sedative actions, the former action being suspected to be central in nature. However, no difference of pharmacological action, either qualitatively or quantitatively, between peiminine and peiminine has thus far been demonstrated.