[Risperidone and concept of bipolar neuroleptic]

We present a review of the stimulant properties of risperidone, analyzing them according to the model of bipolar neuroleptic proposed in 1979 by Colonna and Petit. The bipolar neuroleptics (pimozide, sulpiride) present stimulant properties at low dose and sedative effects at high dose whereas monopolar neuroleptics (levomepromazine, chlorpromazine) present from the low dose sedative effects. The stimulant properties might arise from a preferential blockade of the presynaptic dopaminergic receptors, giving and enhancement of the dopaminergic transmission. Risperidone might follow the bipolar model; we review the stimulant effects in laboratory animals and in clinical settings, showing exacerbation of manic symptoms and a possible antidepressive effect. These properties could be due to the capacity to increase the cerebral monoamines by the 5-HT2A and alpha 2 antagonism. Risperidone could be used in the treatment of clinical syndromes combining depressive and psychotic symptoms.