Drug Inhibition of First-Stage Radioemesis.

Abstract : An animal model of irradiation-induced emesis was developed which involved exposing young male beagle dogs to 800 rads in the abdominal area. This caused a 100% incidence of emesis within 8 hr and a second wave of emesis and hemorrhagic diarrhea approximately 48 hr later. Seven drugs and one combination of two drugs were examined for effects against these responses. Chlorpromazine proved to be the most potent antagonist of first-stage emesis while dimenhydrinate and diphenhydramine HC1 showed the same activity but to a lesser degree. Inactive drugs were phenytoin sodium, perphenazine (at a low dose), WR2721, and the combination of amphetamine plus scopolamine. Acetylsalicylic acid intensified the emetic responses. (Author)