“…Evidence suggests that caramiphen exerts its antitussive effect centrally (Domino et al, 1985), although others have suggested it should be classified as a peripherally acting drug (Bolser et al, 1995a). Domenjoz (1952) found it equivalent to codeine in suppressing cough evoked by mechanical stimulation of rat trachea. Subsequent animal experiments confirmed this antitussive effect when caramiphen was administered intravenously (Toner and Macko, 1952;Chakravarty et al, 1956), although caramiphen was largely ineffective when administered orally (Stefko et al, 1961).…”