Objectives: The primary study objective was to assess the time course and intensity of sedation after administration of immediate-release (IR) and extended-release (XR) quetiapine fumarate in healthy subjects during dose initiation. The tolerability of the 2 formulations was also evaluated.
Methods: This was a randomized, double-blind, double-dummy, 2-period crossover study in healthy adult (age 18-50 years) subjects. It employed the dose-initiation schedule used in studies of the 2 quetiapine formulations in patients with bipolar depression: 50 mg on day 1, 100 mg on day 2, 200 mg on day 3, and 300 mg on days 4 and 5. Doses were administered in the morning. The primary end point was the level of sedation 1 hour after dosing on day 1, as rated by subjects using a visual analog scale (VAS) ranging from 0 = alert to 100 = drowsy. Secondary VAS end points included sedation over a 14-hour period on day 1, and on days 2 through 5. Blood was drawn on day 5 of both periods for determination of plasma drug concentrations by a liquid chromatography method with tandem mass-spectrometric detection. Adverse events (AEs) were recorded throughout the study.
Results: Sixty-three subjects were enrolled in the study, comprising the safety population. The perprotocol population consisted of 58 subjects (79.0% male, 21.0% female; 67.2% black, 24.1% white; mean age, 31.8 years; mean weight, 80.7 kg). One hour after dosing on day 1, sedation was significantly greater with quetiapine IR than with quetiapine XR (mean VAS score, 33.2 vs 11.3, respectively; P < 0.001). There were no significant differences in sedation between formulations at 7 hours after dosing (64.5 and 53.6), 8 hours after dosing (46.9 and 50.8), or 14 hours after dosing (both, 12.7). On day 1, numerically more subjects had a VAS score>75 (substantial sedation) 1 hour after dosing in the quetiapine IR group than in the quetiapine XR group (14 vs 4 subjects). On day 5, the mean (95% CI) quetiapine C(max) for the IR and XR formulations was 689.19 (605.83-784.02) and 381.70 (341.40-426.76) ng/mL; the mean was AUC(0-11) was 2835.89 (2517.92-3194.02) and 2515.21 (2281.76--2772.55) ng . h/mL; and the median T(max) was 2.0 and 5.0 hours. The incidence of any AEs was 21.7% with quetiapine IR and 9.8% with quetiapine XR.
Conclusion: In these healthy subjects, quetiapine XR was associated with a lower intensity of self-reported sedation compared with quetiapine IR. ClinicalTrials.gov Identifier: NCT00702676; Astra Zenecaclinicaltrials.com Identifier: D1443C00033.