A retrospective study of clinical usage of quetiapine XR and quetiapine IR in outpatients with schizophrenia in Denmark.

OBJECTIVES: The atypical antipsychotic quetiapine is a first-line treatment for schizophrenia. This non-interventional study (NCT01212575) evaluated the clinical use of its two formulations, extended release (XR) and immediate release (IR), in outpatients with schizophrenia spectrum disorder. METHODS: Patients who had received at least one dose of quetiapine XR and/or IR were included. A dosage ≥400 mg/day was defined as antipsychotic. Medical records data were collected retrospectively. RESULTS: Of 186 enrolled patients, 99 (53%) and 87 (47%) received quetiapine XR and IR, respectively. Use in antipsychotic dosage was seen for 89% XR versus 63% IR patients (mean daily dose ≥400 mg/day; p < 0.0001). 75% XR and 53% IR patients used dosages ≥600 mg/day (p = 0.0019). Quetiapine XR was used at higher mean daily dosages than IR (748 vs 566 mg/day; p = 0.006). Forty-three patients (23%) used both formulations concomitantly; 55 patients (30%) used either XR or IR. Quetiapine IR was used as-needed in 44 patients (23%); one patient used XR as-needed. CONCLUSIONS: Quetiapine XR was used more often in higher (antipsychotic) dosages; quetiapine IR more frequently on an as-needed administration basis. Concomitant use was seen. These findings probably reflect the different profiles of XR/IR and advocate the need for both formulations to offer treatment choice.

Use of quetiapine XR and quetiapine IR in clinical practice for hospitalized patients with schizophrenia: a retrospective study.

Quetiapine fumarate, a first-line treatment for schizophrenia, exists in two formulations: extended release (XR) and immediate release (IR). This naturalistic, noninterventional study evaluated use of quetiapine XR/IR among in-patients with schizophrenia [ClinicalTrials.gov identifier: NCT01214135]. Data were collected from medical records. Categorical and numerical outcomes were compared using χ(2) and t tests. Of 178 enrolled patients, 66% and 34% used quetiapine XR and IR respectively. Based on mean daily dose, XR was used as antipsychotic medication in 64% of patients compared with 40% of patients on IR (dose ≥ 400 mg/day; p = 0.002) and in higher doses than IR (494 versus 345 mg/day; p = 0.001; calculated averages). Schizophrenia was more commonly reported as reason for use of XR than IR (20% versus 0%; p = 0.0003). Patients with comorbid substance abuse or somatic disease were more likely to receive XR (p = 0.003; p = 0.03). Treatment cessation due to nonadherence was less common in patients on XR (3.4% versus 12%; p = 0.03). Polypharmacy was seen in 98% of patients. Quetiapine XR/IR usage varies in hospitalized patients with schizophrenia. XR is more often used in antipsychotic dosage; IR is more commonly used at lower doses as add-on therapy. Both quetiapine XR and IR have their place in clinical practice and provide treatment choice in schizophrenia.

Pharmacology of a novel selective 5-hydroxytryptamine1B receptor antagonist, AR-A000002.

The terminal 5-HT(1B) autoreceptors have attracted great pharmacological interest since they are potential targets for compounds modifying serotonergic neurotransmission. In the present work the in vivo biochemical properties of AR-A000002 ((R)-N-[5-methyl-8-(4-methylpiperazin-1-yl)-1,2,3,4-tetrahydro-2-naphthyl]-4-morpholinobenzamide), a novel selective 5-HT(1B) receptor antagonist, are reported. The effects of AR-A000002 on: 5-HT metabolism was measured as the ratio between 5-HIAA and 5-HT concentrations in different brain regions; 5-HT synthesis was measured as the accumulation of 5-HTP after inhibition of the aromatic amino acid decarboxylase activity with m-hydroxybenzylhydrazine (NSD1015); 5-HT release was measured using the microdialysis technique. 5-HT, 5-HIAA and 5-HTP concentrations were analyzed using high power liquid chromatography (HPLC) with electrochemical detection. AR-A000002 significantly enhanced 5-HT metabolism (5-HIAA/5-HT ratio) and 5-HT synthesis in guinea pig brain in the dose range 0.9-18 mg/kg s.c. (ED(50)=1 mg/kg s.c. in the four brain regions examined) with maximal effect seen after 2-4 h. AR-A000002 (9 mg/kg s.c.) significantly increased the extracellular concentrations of 5-HT and 5-HIAA by 20% in the guinea pig frontal cortex, measured with the in vivo microdialysis technique in freely moving guinea pigs. AR-A000002 (9 mg/kg s.c.) in combination with the 5-HT uptake inhibitor citalopram (5 mg/kg s.c.) increased the extracellular 5-HT concentration in guinea pig frontal cortex from 250 to 400% of the basal level. Citalopram alone decreased the extracellular 5-HIAA levels to 70% of the basal value. AR-A000002 counteracted the citalopram-induced decrease in 5-HIAA. Since the basal level of extracellular 5-HIAA was 160 times higher than that of 5-HT the 20% increase in 5-HIAA concentrations indicates that only a few percent of the exocytotically released 5-HT from the nerve terminals reached the extracellular space when the re-uptake mechanism was intact. The results also show that the terminal 5-HT(1B) autoreceptors are tonically activated under drug-free as well as citalopram conditions. The increase in plasma level of cortisol after AR-A000002 administration may indicate stimulation of post-synaptic 5-HT receptors. AR-A000002 also blocked 5-HT(1B) agonist-induced (CP-135,807) decrease in 5-HT metabolism and hypothermia (ED(50)=1 mg/kg s.c.), thus indicating competition between these two drugs. It is concluded that AR-A000002 is a 5-HT(1B) receptor antagonist that enhances the serotonergic neurotransmission in guinea pig brain.