Antipsychotic Tolerance: Evaluating the Behavioural Effects of Continuous Versus Intermittent Haloperidol Exposure

There are several lines of investigation, both preclinical and clinical, that suggest antipsychotic drug (APD) tolerance may occur. Using a behavioural animal model, the present study examined whether the amount of APD exposure (i.e. continuous versus intermittent) significantly impacts APD efficacy. More specifically, it was investigated whether continuous haloperidol (an APD) exposure, in comparison to intermittent, would lead to a decrease in response over time. Catalepsy, locomotor activity, and exploratory behaviour were assessed weekly, over the course of 21 days, in rats receiving haloperidol continuously or intermittently. Our findings are consistent with earlier preclinical reports that have implicated chronic and continuous APD therapy in reduced drug effect. This line of investigation has immediate and direct implications in terms of current guidelines regarding maintenance antipsychotic treatment. Moving forward, we are in a position to translate these results to clinical studies that can further examine this issue in humans.M.Sc