Atypical neuroleptics increase self-administration of cocaine: an evaluation of a behavioural screen for antipsychotic activity.

Several drugs have been shown to exert antipsychotic effects, yet they display an atypical profile with respect to standard neuroleptic drug screens. Low doses of traditional neuroleptics are known to increase self-administration of psychomotor stimulants; we sought to determine whether these atypical drugs would cause a comparable effect. Sulpiride, metoclopramide and thioridazine produced a dose-dependent increase in cocaine intake similar to that found for chlorpromazine, haloperidol, pimozide and flupenthixol. This effect was found to correlate (r = 0.94) with daily clinical dose. Clozapine, however, produced a dose-dependent decrease in cocaine intake. The advantages and disadvantages of using this measure as a screening procedure for neuroleptic drugs are discussed.