Assessment of centanafadine in adults with attention-deficit/hyperactivity disorder: A matching-adjusted indirect comparison vs lisdexamfetamine dimesylate, atomoxetine hydrochloride, and viloxazine extended-release.

BACKGROUND: Head-to-head trials comparing centanafadine, an investigational therapy for adults with attention-deficit/hyperactivity disorder (ADHD), with other treatment options are lacking. OBJECTIVE: To compare safety and efficacy outcomes of centanafadine sustained-release vs lisdexamfetamine dimesylate (lisdexamfetamine), atomoxetine hydrochloride (atomoxetine), and viloxazine extended-release (viloxazine ER), respectively, using matching-adjusted indirect comparison (MAIC). METHODS: This MAIC included patient-level data pooled from 2 centanafadine trials (NCT03605680 and NCT03605836) and published aggregate data from comparable trials of 3 comparators-lisdexamfetamine (NCT00334880), atomoxetine (NCT00190736), and viloxazine ER (NCT04016779)-in adult patients with ADHD. Propensity score weighting was used to match characteristics of individual patients from the centanafadine trials to aggregate baseline characteristics from the respective comparator trials. Safety outcomes were rates of adverse events for which information was available in the centanafadine and respective comparator trials. Efficacy outcome was mean change from baseline in the Adult ADHD Investigator Symptom Rating Scale (AISRS) score (ADHD Rating Scale [ADHD-RS] was used as proxy in the comparison with lisdexamfetamine). Anchored indirect comparisons were conducted across matched populations of the centanafadine and respective comparator trials. RESULTS: After matching, baseline characteristics in the centanafadine trials were the same as those in the respective comparator trials. Compared with lisdexamfetamine, centanafadine was associated with a significantly lower risk of lack of appetite (risk difference [RD] in percentage points: 23.42), dry mouth (19.27), insomnia (15.35), anxiety (5.21), nausea (4.90), feeling jittery (3.70), and diarrhea (3.47) (all P < 0.05) but a smaller reduction in the AISRS/ADHD-RS score (6.58-point difference; P < 0.05). Compared with atomoxetine, centanafadine was associated with a significantly lower risk of nausea (RD in percentage points: 18.64), dry mouth (17.44), fatigue (9.21), erectile dysfunction (6.76), lack of appetite (6.71), and urinary hesitation (5.84) (all P < 0.05) and no statistically significant difference in the change in AISRS score. Compared with viloxazine ER, centanafadine was associated with a significantly lower risk of fatigue (RD in percentage points: 11.07), insomnia (10.67), nausea (7.57), and constipation (4.63) (all P < 0.05) and no statistically significant difference in the change in AISRS score. CONCLUSIONS: In an anchored MAIC, centanafadine showed a significantly better short-term safety profile than lisdexamfetamine, atomoxetine, and viloxazine ER; efficacy was lower than with lisdexamfetamine and comparable (ie, nondifferent) with atomoxetine and viloxazine ER. This MAIC provides important insights on the relative safety and efficacy of common treatment options to help inform treatment decisions in adults with ADHD. Safety assessment was limited to rates of adverse events reported in both trials of a given comparison. STUDY REGISTRATION NUMBERS: NCT03605680, NCT03605836, NCT00334880, NCT00190736, and NCT04016779.

The role of placebo response in the efficacy outcome assessment in viloxazine extended-release pivotal trials in paediatric subjects with attention-deficit/hyperactivity disorder.

AIMS: Four Phase 3 studies evaluated efficacy and safety of viloxazine extended-release in the treatment of attention-deficit/hyperactivity disorder (ADHD). The primary efficacy objective-change from baseline in ADHD Rating Scale-5 (ADHD-RS-5) Total score at end of study (EOS)-was not met in one of the studies (812P304). A band-pass analysis was performed to evaluate the impact of placebo response on the results. METHODS: The distribution of placebo response at EOS of each trial was evaluated. The 2.5th and 97.5th percentiles of the distribution of ADHD-RS-5 Total score were used as boundaries for the band-pass analysis. An independent mixed model for repeated measures analysis was conducted for each trial using all eligible data (active and placebo) from the total and band-pass filtered populations. RESULTS: The 2.5th and 97.5th percentiles at EOS were 3.5 and 53.5, respectively. Application of the band-pass filter (filtering out all subjects [active, n = 305 (32.1%) and placebo, n = 134 (33.5%)] of clinical sites with placebo scores <3.5 or >53.5) revealed statistically significant improvement at the primary endpoint (600-mg/d viloxazine ER vs. placebo) in Study 812P304 (mean [confidence interval] = 4.9537 [0.5405-9.3669]), previously masked by a high placebo response (mean [confidence interval] = 3.5756 [-0.3332-7.4844]). The outcome of the analysis indicated that the impact of the band-pass adjustment is greater when placebo response is higher. CONCLUSION: This analysis indicated that a higher placebo response in Study 812P304 confounded the assessment of treatment effect. Application of the band-pass methodology confirmed the positive results of the 3 prior studies and the signal detection confounder in the fourth study.

Population Pharmacokinetics of Viloxazine Extended-Release Capsules in Pediatric Subjects With Attention Deficit/Hyperactivity Disorder.

Viloxazine extended-release capsules (viloxazine ER; Qelbree) is a novel nonstimulant, recently approved by the US Food and Drug Administration for the treatment of ADHD in pediatrics. Here, we characterize the pharmacokinetics (PK) of viloxazine and its major metabolite, 5-HVLX-gluc, using a population PK model and evaluate the impact of 1-4 days of missed viloxazine ER doses on viloxazine PK. Data from 4 phase 3 trials in pediatric subjects treated with viloxazine ER were used to establish the PK model. Covariate analysis was conducted on the final base model. The impact of 1-4 days of missed doses on steady-state viloxazine PK was evaluated using Monte Carlo simulations. A 1-compartmental linear model with first-order absorption and elimination of the parent drug and first-order metabolite formation and elimination properly described the population PK of viloxazine and 5-HVLX-gluc. Body weight impacted the systemic exposure of viloxazine and 5-HVLX-gluc. Predicted PK parameters at steady state (mean ± standard deviation) in children receiving viloxazine ER were determined. Cmax was 1.60 ± 0.70 µg/mL at 100 mg, 2.83 ± 1.31 µg/mL at 200 mg, and 5.61 ± 2.48 µg/mL at 400 mg. AUC0-t was 19.29 ± 8.88 µg·h/mL at 100 mg, 34.72 ± 16.53 µg·h/mL at 200 mg, and 68.00 ± 28.51 µg·h/mL at 400 mg. PK parameters for adolescents receiving viloxazine ER were also determined. Cmax was 2.06 ± 0.90 µg/mL at 200 mg, 4.08 ± 1.67 µg/mL at 400 mg, and 6.49 ± 2.87 µg/mL at 600 mg. AUC0-t was 25.78 ± 11.55 µg·h/mL at 200 mg, 50.80 ± 19.76 µg·h/mL at 400 mg, and 79.97 ± 36.91 µg·h/mL at 600 mg. Simulations revealed that, regardless of the duration of the dosing interruption, viloxazine concentration returned to steady-state levels after approximately 2 days of once-daily dosing of viloxazine ER.

Metabolism and in vitro drug-drug interaction assessment of viloxazine.

Viloxazine is currently being developed as a treatment for attention deficit/hyperactivity disorder (ADHD). The aim of these studies is to update the understanding of the rat and human metabolism and the in vitro drug-drug interaction profile of viloxazine to a degree where it meets current regulatory standards for such investigations. In vivo absorption-distribution-metabolism-excretion (ADME) studies demonstrated that in humans 5-hydroxylation followed by glucuronidation is the major metabolic route. This route was also seen as a minor route in rats where the major route is O-deethylation with subsequent sulfation. In humans, the 5-hydoxylation pathway is mediated by CYP2D6. An estimate for the fraction of the metabolism via this pathway suggests a PM/EM difference of <2-fold, making it highly unlikely that this will be an issue of clinical significance. Viloxazine forms a unique N-carbamoyl glucuronide in humans. The chemical reactivity characteristics of this metabolite are similar to stable glucuronide conjugates and dissimilar from acyl glucuronides; therefore, it is regarded as a stable Phase II conjugate. In vitro drug-drug interaction (DDI) testing indicates that viloxazine is not a significant inhibitor or inducer of CYPs and transporters with the exception of CYP1A2.