Nonspecific effect of bis(2-ethylhexyl) phthalate on hexobarbital sleep time.

The data presented suggest that the intravenous or intraperitoneal administration of bis(2-ethylhexyl) phthalate prolongs hexobarbital sleep time in mice and rats by enlarging the lipophilic pool, a phenomenon that can be replicated by pretreatment of the animals with olive oil. These results call attention to the importance of considering the physical characteristics of a substance when evaluating its effect on a pharmacologically active agent.