A single injection of either flupenthixol decanoate or haloperidol decanoate produces long-term changes in cocaine self-administration in rats.

The effect of decanoate forms of flupenthixol and haloperidol on cocaine self-administration was evaluated. Forty-two male Wistar rats were implanted with chronically indwelling jugular cannulae and trained to self-administer cocaine (0.6 mg/inj) either on a fixed ratio (FR) 1 schedule or a progressive ratio (PR) schedule. After a stable response pattern was established, animals received a single i.m. injection of either flupenthixol (2.0 mg), haloperidol (2.5 mg) or vehicle (0.1 ml oil). Both neuroleptics produced a long lasting increase in cocaine intake on a FR 1 schedule which reached a peak on post-injection day three and diminished slowly over the next seven days. All animals maintained on a PR schedule showed a long lasting decline in breaking points. These data suggest that the decanoate forms of flupenthixol and haloperidol may attenuate the reinforcing effects of cocaine and indicate that the therapeutic value of depot neuroleptics as anti-cocaine treatments would depend on the economics of cocaine availability.