A NEW ANTITUSSIVE METHOD INVOLVING MECHANICAL STIMULATION IN UNANESTHETIZED DOGS

¹ Research and Development Division, Smith, Kline and French Laboratories, Philadelphia, Pa

A procedure involving mechanical stimulation of the trachea to evoke the cough reflex has been described. The method has the following advantages. First and foremost, the test is performed in unanesthetized dogs. This is especially important because of the great number of compounds which have been found to potentiate the effects of the barbiturates. The mechanical stimulus has the advantage of simplicity and efficacy. The untreated animal coughs invariably. The mechanically-induced cough is evoked with a stimulus of threshold proportions and the response is a bonafide cough in as much as the glottis is not by-passed, i.e., the effects of antitussives are not studied on an inspiratory or expiratory gasp in a tracheotomized animal. The cough response is consistent, in that animals do not become refractory to repeated testing over a period of at least a year. Codeine and morphine were shown to have an antitussive action on the mechanically-induced cough response in nontoxic doses. In marked contrast, pentobarbital produced an antitussivc effect only in doses which caused overt signs of neurological deficit.