A case of risperidone-induced hypothermia.

Risperidone is one of the second-generation antipsychotics (SGAs). Use of SGAs or so-called atypical antipsychotics is becoming more frequent because they are more efficacious and safer than typical antipsychotics. This is due to their ability to occupy some other receptors as well as dopamine type 2 (D(2)) receptors in the brain. Risperidone has more affinity for serotonin type 2 (5-HT(2)) than for D(2) receptors. This accounts for its better treatment of negative symptoms of schizophrenia and fewer extrapyramidal side effects when compared with typical antipsychotics. Common side effects associated with risperidone include extrapyramidal symptoms, dizziness, nausea, weight gain, sleep disturbance, and sexual dysfunction. We describe here a case of risperidone-induced hypothermia. Body temperature is regulated by the preoptic anterior hypothalamus with involvement of dopamine, serotonin, norepinephrine, and alpha-adrenergic receptors. Experimental data suggest that stimulation of 5-HT(2) and dopamine receptors can increase the body temperature. Additional clinical evidence indicates potent antagonists of 5-HT(2) are more likely to cause hypothermia. Risperidone has higher potency for occupying 5-HT(2) than D(2) receptors.