Approach to Evaluating QT Prolongation of Quetiapine Fumarate in Late Stage of Clinical Development Using Concentration-QTc Modeling and Simulation in Japanese Patients With Bipolar Disorder.

PURPOSE: Quetiapine has been reported to prolong the QT interval, and has been used as a positive control in thorough QT studies. The objective of the present study was to evaluate, in the late stages of clinical development, the QT-prolongation effects of the extended-release (XR) formulation of quetiapine at the approved dose in Japanese patients with bipolar disorder, using concentration-QT modeling and simulation. METHODS: Plasma concentrations of quetiapine and 4 of its metabolites (M1, M2, M4, and M5), and the QT interval corrected using the Fridericia formula (QTcF), were used for the concentration-QT analysis. Data from intensive electrocardiogram monitoring at predose and at 4, 6, 10, and 24 h after the administration of the last dose were pooled from a Phase I trial (6949-CL-0006) and from sparse sampling in late-stage clinical trials (6949-CL-0005, -0021, -0022, and -0023) in Japanese patients (N = 505). The upper limit of 1-sided 95% confidence interval (CI) of the changes from baseline in QTcF (ΔQTcF) at the geometric mean Cmax of a therapeutic dose of 300 mg once daily was predicted using a linear mixed-effects model, with the intercept as a random effect specifying a subject effect. FINDINGS: For quetiapine and M2, but not M1, M4, or M5, positive slopes were observed between ΔQTcF and concentration. The predicted upper limits of the 1-sided 95% CIs did not exceed the regulatory threshold of 10 msec. Therefore, QTc prolongation is unlikely to be clinically relevant at the approved dose of quetiapine XR. IMPLICATIONS: In this pooled data analysis of the QT-prolongation effects of the quetiapine XR, positive relationships between ΔQTcF and quetiapine and M2 concentrations were observed. However, the predicted upper limits of the 1-sided 95% CIs did not exceed 10 msec. Therefore, QTc prolongation is unlikely to be clinically relevant at the approved dose. ClinicalTrials.gov identifiers: NCT01725282, NCT01919008, NCT01725308, NCT01737268, and NCT02362412.

Population Pharmacokinetics Analysis of Quetiapine Extended-release Formulation in Japanese Patients with Bipolar Depression.

PURPOSE: The objectives of this study were to explore covariates of plasma quetiapine concentrations after oral administration of quetiapine extended-release formulation (XR), and to examine the exposure-response relationship in Japanese patients with bipolar depression, using population pharmacokinetics (PopPK) modeling. METHODS: In a multicenter, randomized, double-blind, placebo-controlled study of quetiapine XR in patients with bipolar depression, plasma for the measurement of quetiapine concentration was collected at weeks 2, 4, 8, 12, 20, 28, and 52 during oral administration of 150 or 300 mg once daily of quetiapine XR before bedtime. A PopPK model of quetiapine XR was developed using nonlinear mixed-effects modeling with first-order conditional estimation with interactions. The exposure-response relationship was examined using post-hoc exposures. The post-hoc AUC estimate was plotted against the change in the Montgomery-Åsberg Depression Rating Scale (ΔMADRS) total score from baseline to 8 weeks following once-daily doses at 300 mg. FINDINGS: The final PopPK analysis dataset contained 322 patients and 1162 observations (cutoff data at week 28; cutoff date, February 2016). The plasma quetiapine concentration-time profile in patients with bipolar depression after oral administration of quetiapine XR was represented well using a 1-compartment with first-order absorption model. Covariate analysis led to the selection of γ-glutamyl transpeptidase on apparent oral clearance and body weight on apparent volume of distribution as covariates. The final population mean values of apparent oral clearance and apparent volume of distribution were 87.7 L/h and 277 L, respectively, and the interindividual %CVs were 32.6% and 75.0%, respectively. IMPLICATIONS: The effects of covariates on PK parameters were not large compared with the interindividual variability. In addition, there was no clear relationship between the AUC and ΔMADRS. ClinicalTrials.gov identifier: NCT01725308.

Pharmacokinetics and Safety of Enzalutamide in Healthy Chinese Male Volunteers.

PURPOSE: This open-label, single-dose study evaluated the pharmacokinetic profiles of enzalutamide and its major metabolites and the safety of enzalutamide in healthy, Chinese male volunteers. METHODS: Fourteen volunteers (median age, 28.5 years) received a single oral dose of enzalutamide (160 mg) under fasting conditions on day 1 and were followed for 50 days. Pharmacokinetic profiles were obtained for enzalutamide and its major metabolites, carboxylic acid metabolite (M1; inactive metabolite) and N-desmethyl enzalutamide (M2; active metabolite), on day 1 up to 1176 hours (49 days). Safety data were also collected. FINDINGS: Enzalutamide plasma concentration rapidly increased (median Tmax, 1.5 hours) followed by a slow decrease (mean t½, 90.7 hours). M1 and M2 plasma concentrations increased gradually with a median Tmax of 72.0 and 121 hours, respectively. M1 and M2 mean metabolite-to-parent ratios were 0.2 and 1.3, respectively. Mean AUC0-∞ of enzalutamide plus M2 was 828 µg h/mL versus 368 µg h/mL for enzalutamide alone. Mean t½, maximum concentration, and Tmax of enzalutamide plus M2 were comparable with those of enzalutamide. Drug-related treatment-emergent adverse events were reported in 4 men (28.6%): 1 each of upper respiratory tract infection, chest discomfort, increased blood bilirubin, and decreased white blood cell count. No deaths or serious treatment-emergent adverse events were observed. IMPLICATIONS: The pharmacokinetic profiles of enzalutamide, M1, M2, and enzalutamide plus M2 in healthy Chinese men were generally consistent with those in white men. No new safety concerns were found. Chinese Clinical Trial Registration identifier: CTR20150635.