An Open-Label Investigation of the Pharmacokinetic Profiles of Lisdexamfetamine Dimesylate and Venlafaxine Extended-Release, Administered Alone and in Combination, in Healthy Adults

Abstract

BackgroundLisdexamfetamine dimesylate (LDX), a prodrug consisting of d-amphetamine and l-lysine, is being studied in clinical trials of major depressive disorder. Additional drug-drug interaction studies were warranted.ObjectiveThis study aimed to describe the pharmacokinetics and safety of LDX and venlafaxine extended-release (VXR), alone or combined.Study DesignThe study was an open-label, two-arm, single-sequence crossover investigation with randomization to treatment sequence.Setting and ParticipantsThe study was conducted at two clinical study centres and included healthy adult males and females (18–45 years of age).InterventionThe study included two single-sequence crossover designs: LDX alone followed by LDX + VXR (Treatment Arm A); and VXR alone followed by VXR + LDX (Treatment Arm B). Drug treatment was initiated on day 1 with once-daily LDX or VXR alone with 15 days’ titration to final dose (LDX 30, 50 and 70 mg for 5 days each; VXR 75, 150 and 225 mg for 5 days each). On days 16–30, VXR, titrated to a final dose of 225 mg, or LDX, titrated to a final dose of 70 mg, was coadministered for participants in Treatment Arm A or B, respectively. On days 31–38, VXR doses were tapered.Main Outcome MeasuresOn days 1–2, 15–16 and 30–31, safety evaluations and blood samples were obtained pre-dose through 24 h post-dose for analysis of LDX, d-amphetamine, venlafaxine (VEN), and O-desmethylvenlafaxine (ODV). Combination treatment was considered bioequivalent to single treatment if 90 % confidence intervals (CIs) for geometric mean ratios (GMRs) of analytes fell within the interval 0.80–1.25 based on maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) from time zero to time of last measurable concentration (AUCτ). Safety assessments included treatment-emergent adverse events (TEAEs), pulse rate and blood pressure (BP), clinical laboratory assessments, and 12-lead electrocardiograms (ECG).ResultsAmong 80 enrolled subjects, 77 were included in pharmacokinetic and safety analyses. Combination LDX + VXR was bioequivalent to LDX alone, based on exposure to d-amphetamine (GMR [95 % CI], Cmax (ng/mL): 0.97 [0.82, 1.14], AUCτ: 0.95 [0.81, 1.12]). Exposure to VEN with LDX + VXR (vs. VXR alone) was increased (Cmax: 1.10 [0.88, 1.38], AUCτ: 1.13 [0.88, 1.45]) and ODV decreased (Cmax: 0.91 [0.77, 1.06], AUCτ: 0.83 [0.71, 0.96]), whereas composite VEN + ODV was bioequivalent to VXR alone (Cmax: 0.96 [0.84, 1.09], AUCτ: 0.98 [0.85, 1.13]). TEAEs with LDX or LDX + VXR were similar. Maximum mean increases from baseline were: pulse rate, +8.73 to 12.76 beats/min with either treatment alone and +17.67 to 20.85 beats/min with LDX + VXR; systolic BP, +4.32 to 6.56 mmHg with either treatment alone and +12.96 to 13.78 mmHg with LDX + VXR; diastolic BP, +5.39 to 5.74 mmHg with either treatment alone and +12.09 to 12.46 mmHg with LDX + VXR. One participant was withdrawn due to a serious TEAE (presyncope). No unexpected, clinically meaningful trends or changes from baseline in mean laboratory or ECG parameters were observed during the trial.ConclusionIn healthy adults, combination LDX + VXR (vs. LDX alone) did not alter exposure to d-amphetamine. Although small changes in exposure to VEN (increased) and ODV (decreased) were seen with combination treatment, total VEN + ODV exposure showed no change (vs. VEN alone). LDX + VXR led to increases in BP and pulse rate, supporting existing recommendations for vital sign monitoring when using these medications.