Antagonism of Apomorphine by Chlorinated Phenothiazines

Induction of the pecking syndrome with apomorphine was attempted in pigeons premedicated with a variety of central nervous system depressants and ataraxics. Of the agents employed, the chlorinated phenothiazines (chlorpromazine, prochlorperazine, and perphenazine) proved most effective in inhibiting the apomorphine-induced response. Hydroxyzine exhibited a lesser but significant degree of inhibition while pentobarbital, morphine, nalorphine, promazine, mepazine, and meprobamate were ineffective in modifying the syndrome. Several of the premedicants (nalorphine, meprobamate, mepazine, and hydroxyzine) were observed to potentiate the ordinarily trivial emesis provoked in pigeons by apomorphine.