Pharmacokinetics and D2 receptor occupancy of long-acting injectable risperidone (Risperdal Consta) in patients with schizophrenia.

Thirteen patients with schizophrenia received injections of 25, 50, or 75 mg of long-acting risperidone every 2 wk. Brain D2 receptor occupancy was assessed with [11C]raclopride 2 wk after the last (fifth) injection (day 71) in seven subjects and 2 wk after the third injection (day 44) in one subject. Stable plasma concentrations were reached after the third injection and steady-state concentrations of the active moiety (risperidone + 9-hydroxyrisperidone) after the fourth injection.

Treatment of schizophrenia with long-acting injectable risperidone: a 12-month open-label trial of the first long-acting second-generation antipsychotic.

Background: The long-term safety and efficacy of long-acting injectable risperidone, the first long-acting second-generation antipsychotic, were evaluated in stable patients with schizophrenia.

Method: After a 2-week run-in period during which patients with DSM-IV schizophrenia received flexible doses of 1 to 6 mg of oral risperidone, patients received injections of 25 mg, 50 mg, or 75 mg of long-acting risperidone every 2 weeks for 12 months. Severity of extrapyramidal symptoms was assessed with the Extrapyramidal Symptom Rating Scale (ESRS), and efficacy was assessed with the Positive and Negative Syndrome Scale (PANSS).

Different corticostriatal patterns of L-DOPA utilization in patients with untreated schizophrenia and patients treated with classical antipsychotics or clozapine.

Positron emission tomography (PET) has been shown to be of great importance in elucidating the mechanism of action of antipsychotic drugs. In psychotic patients L-[11C]DOPA PET has been used to demonstrate some differences in dopaminergic activity compared with that in healthy volunteers. Ten healthy volunteers were investigated with PET and L-[11C]DOPA.

D(2) and 5HT(2A) receptor occupancy of different doses of quetiapine in schizophrenia: a PET study.

Objective: Quetiapine is a novel antipsychotic agent with many atypical features, including low D(2) and higher 5HT(2A) affinity in vitro, low propensity to induce extra-pyramidal side effects and minimal effects on prolactin levels. The purpose of this study was to investigate, using positron emission tomography (PET), the relationship between plasma concentrations of different doses of quetiapine and occupancy of D(2) and 5HT(2A) receptors in schizophrenic patients.

Methods: Five patients were treated with quetiapine (titrated to 750 or 450 mg/day) for 28 days, subsequently reduced weekly in a descending-dose schedule.

Analysis and pharmacokinetics of quetiapine and two metabolites in human plasma using reversed-phase HPLC with ultraviolet and electrochemical detection.

A sensitive and specific HPLC assay for the measurement of the antipsychotic compound quetiapine in human plasma has been developed and validated. The assay employs a three-step liquid liquid extraction of quetiapine and its 7-hydroxylated and 7-hydroxylated, N-dealkylated metabolites from human plasma, and utilizes ultraviolet (UV) detection of quetiapine and electrochemical detection of the metabolites. The method provides a linear response from a quantitation limit of 2.