Effects of cannabidiol in animal models predictive of antipsychotic activity

The effects of cannabidiol (CBD) were compared to those produced by haloperidol in rats submitted to experimental models predictive of antipsychotic activity. Several doses of CBD (15–480 mg/kg) and haloperidol (0.062–1.0 mg/kg) were tested in each model. First, CBD increased the effective doses 50% (or) ED₅₀ of apomorphine for induction of the sniffing and biting stereotyped behaviors. In addition, both CBD and haloperidol reduced the occurrence of stereotyped biting induced by apomorphine (6.4 mg/kg), increased plasma prolactin levels and produced palpebral ptosis, as compared to control solutions. However, CBD did not induce catalepsy even at the highest doses, in contrast to haloperidol. Such a pharmacological profile is compatible with that of an atypical antipsychotic agent, though the mechanism of action is uncertain and may not be identical to that of the dopamine antagonists.