Pharmacological aspects of ipecac syrup (TJN-119)-induced emesis in ferrets.

In order to elucidate the precise mechanism of ipecac syrup (TJN-119) on the occurrence of vomiting, we examined the effects of ipecac syrup on the abdominal afferent nerve activity as well as on the 5-HT levels of the ileum and area postrema in ferrets. Oral administration of TJN-119 (0.5 mg/kg) produced a significant increase in afferent abdominal vagus nerve activity which lasted approximately 1 hour. The maximum response induced by TJN-119 was estimated to be 219 +/- 18% of the pre-injection level. Cephaeline or emetine, the main alkaloids of ipecac syrup, also demonstrated similar effects on afferent vagus nerve activity. TJN-119 increased the 5-HT content in the ileum but not in the area postrema. These observations illustrate possible mechanisms that may act at peripheral sites. It was recently reported that TJN-119 has a high affinity to 5-HT4 receptors (Hasegawa et al., unpublished data). These results suggest that 5-HT4 receptors may be involved in the emetic action of TJN-119.