Little effects of low dosage of levomepromazine on plasma risperidone levels.

In the present study, we investigated the effects of levomepromazine on plasma risperidone concentrations in a steady state. Twenty patients taking risperidone at a stable dose for more than 2 weeks who were considered to require levomepromazine coadministration were selected. The scores of excitement in BPRS significantly decreased 2 weeks after the coadministration of levomepromazine. Plasma risperidone concentrations and the ratio of risperidone and 9-hydroxyrisperidone (risperidone/9-hydroxyrisperidone) did not change between before and 2 weeks after the coadministration of levomepromazine. The extrapyramidal symptoms were not worsened by the coadministration of levomepromazine. These results suggest that a low dosage of levomepromazine, use as a sedative adjuvant to risperidone treatment, have no statistically significant effect on the trough plasma concentrations of risperidone.

Effect of clonazepam treatment on antipsychotic drug-induced Meige syndrome and changes in plasma levels of GABA, HVA, and MHPG during treatment.

We demonstrated the effect of clonazepam (2 mg/day) on Meige syndrome in two schizophrenic patients under continuous treatment with antipsychotic drugs, and changes in the plasma levels of gamma-aminobutyric acid (GABA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) in these cases. The plasma levels of HVA and MHPG during treatment with clonazepam were decreased in the responder, while not changed in the non-responder to clonazepam. A difference between the responder and the non-responder was not found in the plasma GABA levels. These results suggest that hyperactivities of the central dopaminergic and noradrenergic neurones are involved in the pathophysiology of Meige syndrome.