Effects of Strong Inhibition of Cytochrome P450 3A and UDP glucuronosyltransferase 1A9 and Strong Induction of Cytochrome P450 3A on the Pharmacokinetics, Safety, and Tolerability of Soticlestat: Two Drug-Drug Interaction Studies in Healthy Volunteers.

Two open-label, phase 1 studies (NCT05064449, NCT05098041) investigated the effects of cytochrome P450 (CYP) 3A inhibition (via itraconazole), UDP glucuronosyltransferase (UGT) 1A9 inhibition (via mefenamic acid), and CYP3A induction (via rifampin) on the pharmacokinetics of soticlestat and its metabolites M-I and M3. In period 1 of both studies, participants received a single dose of soticlestat 300 mg. In period 2, participants received itraconazole on days 1-11 and soticlestat 300 mg on day 5 (itraconazole/mefenamic acid study; part 1); mefenamic acid on days 1-7 and soticlestat 300 mg on day 2 (itraconazole/mefenamic acid study; part 2); or rifampin on days 1-13 and soticlestat 300 mg on day 11 (rifampin study). Twenty-eight healthy adults participated in the itraconazole/mefenamic acid study (14 per part) and 15 participated in the rifampin study (mean age, 38.1-40.7 years; male, 79-93%). For maximum observed concentration, the geometric mean ratios (GMRs) of soticlestat + itraconazole, mefenamic acid, or rifampin to soticlestat alone were 116.6%, 107.3%, and 13.2%, respectively, for soticlestat; 10.7%, 118.0%, and 266.1%, respectively, for M-I, and 104.6%, 88.2%, and 66.6%, respectively, for M3. For area under the curve from time 0 to infinity, the corresponding GMRs were 124.0%, 100.6%, and 16.4% for soticlestat; 13.3%, 117.0%, and 180.8% for M-I; and 120.3%, 92.6%, and 58.4% for M3. Soticlestat can be administered with strong CYP3A and UGT1A9 inhibitors, but not strong CYP3A inducers (except for antiseizure medications, which will be further evaluated in ongoing phase 3 studies). In both studies, all treatment-emergent adverse events were mild or moderate. SIGNIFICANCE STATEMENT: These drug-drug interaction studies improve our understanding of the potential changes that may arise in soticlestat exposure in patients being treated with CYP3A inhibitors, UGT1A9 inhibitors, or CYP3A inducers. The results build on findings from previously published soticlestat studies and provide important information to help guide clinical practice. Soticlestat has shown positive phase 2 results and is currently in phase 3 development for the treatment of seizures in patients with Dravet syndrome and Lennox-Gastaut syndrome.

Investigation of the absolute bioavailability, mass balance, metabolism, and excretion of the cholesterol 24-hydroxylase inhibitor soticlestat in healthy volunteers.

AIMS: Our aim was to determine the absolute bioavailability, mass balance, metabolism and excretion of soticlestat (TAK-935). METHODS: An open-label, two-period, single-site, phase 1 study was conducted in six healthy men. In Period 1, a single 300 mg dose of soticlestat was administered orally, followed by a 15-min intravenous infusion of [14 C]soticlestat 50 µg (~1 µCi) 10 min later. In Period 2, a single 300 mg dose (~100 µCi) of [14 C]soticlestat in solution was administered orally. Samples were collected, analysed for radioactivity or unchanged soticlestat, and profiled for metabolites. RESULTS: In Period 1, soticlestat had an absolute bioavailability of 12.6% (90% confidence interval, 7.81-20.23%). In Period 2, there was near-complete recovery of total radioactivity (TRA) following a 300 mg dose of [14 C]soticlestat: urine, 94.8% (standard deviation [SD], 1.35%); faeces, 2.7% (SD, 1.67%). Of TRA, 0.1% (SD, 0.09%) and 0.6% (SD, 0.21%) were recovered as soticlestat and metabolite M-I in urine, respectively. In plasma, soticlestat and M-I reached geometric mean maximum observed concentrations of 1352 ng/mL (geometric percent coefficient of variation [gCV%], 61.3) and 253.2 ng/mL (gCV%, 44.1) after 25 min and declined with mean terminal half-lives (SD) of 5.7 (2.90) and 2.0 (0.15) h, respectively. Soticlestat represented 4.9% of TRA in plasma. Soticlestat was rapidly eliminated primarily via O-glucuronidation to metabolite M3, which was the dominant species in plasma (92.6%) and urine (86%). CONCLUSIONS: This study indicates that soticlestat and its metabolites are rapidly cleared and eliminated, lowering the risk of dose accumulation from repeated dosing and supporting further investigation of soticlestat.

Safety and pharmacokinetics of lisdexamfetamine dimesylate in adults with clinically stable schizophrenia: a randomized, double-blind, placebo-controlled trial of ascending multiple doses.

To assess the safety and pharmacokinetics of lisdexamfetamine dimesylate (LDX), a d-amphetamine prodrug, this double-blind study enrolled adults with clinically stable schizophrenia who were adherent (≥12 weeks) to antipsychotic pharmacotherapy. The participants received placebo or ascending LDX doses (50, 70, 100, 150, 200, and 250 mg) daily for 5 days at each dose (dose periods, 1-6; days, 1-5). Of the 31 enrolled participants, 27 completed the study (placebo, n = 6; LDX, n = 21). Treatment-emergent adverse events (AEs) were reported by 4 participants receiving placebo and by 23 participants receiving LDX (all doses) with no serious AEs while on active treatment. For all periods, the mean postdose change on day 5 (up to 12 hours postdose) in systolic and diastolic blood pressure and pulse, respectively, ranged from -4.62 to 8.05 mm Hg, -3.67 to 4.43 mm Hg, and -3.57 to 14.43 beats per minute for placebo and -3.83 to 11.25 mm Hg, -1.55 to 5.80 mm Hg, and -0.36 to 21.26 beats per minute for LDX. With ascending LDX dose, the mean (SD) maximum plasma concentration for LDX-derived d-amphetamine ranged from 51.68 (10.28) to 266.27 (56.55) ng/mL. The area under the plasma concentration-time curve for 24 hours ranged from 801.8 (170.2) to 4397.9 (1085.9) ng[BULLET OPERATOR]h/mL. The d-amphetamine maximum plasma concentration and area under the plasma concentration-time curve increased linearly with ascending LDX dose. Antipsychotic agents did not markedly affect d-amphetamine pharmacokinetics. Over a wide range of ascending doses, LDX safety profile in adults with schizophrenia was consistent with previous findings with no unexpected treatment-emergent AEs. Pulse tended to increase with LDX dose; overall, blood pressure did not increase with LDX dose. Consistent with previous studies, pharmacokinetic parameters increased linearly with increasing LDX dose.

Pharmacokinetics and pharmacodynamics of guanfacine extended release in adolescents aged 13-17 years with attention-deficit/hyperactivity disorder.

The safety and efficacy of guanfacine extended release (up to 4 mg/day) for attention-deficit/hyperactivity disorder (ADHD) in children and adolescents aged 6-17 years is well documented. Data suggest that weight-adjusted doses of guanfacine extended release >0.08 mg/kg but ≤0.12 mg/kg, if tolerated, may provide additional clinical benefits. For many adolescents, such dosing would exceed 4 mg/day, the highest approved dose. This open-label multicenter study evaluated the safety, tolerability, and steady-state pharmacokinetics of guanfacine extended release at escalated forced doses ≤9 mg/day in adolescents (N = 31) aged 13-17 years with ADHD. Following doses of approximately 0.12 mg/kg, the highest weight group (>70-90 kg) exhibited lower mean clearance at steady-state than the lowest weight group (≥30-50 kg). Consistent with its known antihypertensive effects, guanfacine extended release was associated with dose-dependent decreases in blood pressure (BP) and heart rate (HR). The physiologic response of increased BP upon standing was blunted in a dose-related manner while the physiologic response of increased HR upon standing was not substantively affected. The most common treatment-emergent adverse events were somnolence, dizziness, and sinus bradycardia. These results, and those from prior studies, support further examination of the efficacy and safety of higher weight-adjusted doses of guanfacine extended release for ADHD.

Pharmacokinetics of coadministration of guanfacine extended release and methylphenidate extended release.

BACKGROUND: α2-Adrenoceptor agonists are used adjunctively to psychostimulants in treating attention-deficit/hyperactivity disorder (ADHD) when psychostimulants alone do not sufficiently reduce symptoms. However, data on the pharmacokinetic profiles and safety of combination treatments in ADHD are needed. OBJECTIVE: The primary objective of this study was to evaluate the pharmacokinetic profiles of guanfacine extended release (GXR) and methylphenidate hydrochloride (MPH) extended release, alone and in combination. STUDY DESIGN: This was an open-label, randomized, three-period crossover, drug-drug interaction study. SETTING: The study was conducted at a single clinical research center. PARTICIPANTS: Thirty-eight healthy adults were randomized in this study. INTERVENTIONS: Subjects were administered single oral doses of GXR (Intuniv(®); Shire Development LLC, Wayne, PA, USA) 4 mg, MPH (Concerta(®); McNeil Pediatrics, Titusville, NJ, USA) 36 mg, or GXR and MPH combined. MAIN OUTCOME MEASURES: Guanfacine, dexmethylphenidate (d-MPH), and l-methylphenidate (l-MPH) levels were measured with blood samples collected predose and up to 72 h postdose. Safety evaluations included treatment-emergent adverse events (TEAEs), vital signs, and electrocardiograms (ECGs). RESULTS: Thirty-five subjects completed the study. Analyses of the 90 % confidence intervals (CIs) for the geometric mean ratios of the maximum plasma concentration (Cmax) and area under the concentration-time curve extrapolated to infinity (AUC∞) values for guanfacine and d-MPH following administration of GXR or MPH alone or combined met strict bioequivalence criteria (90 % CIs within the interval of 0.80-1.25). Overall, combining GXR and MPH did not alter the pharmacokinetic parameters of either medication. Sixteen subjects (42.1 %) had at least one TEAE. The most commonly reported TEAEs included headache and dizziness following GXR, MPH, and GXR and MPH combined. Two subjects had clinically significant abnormalities in ECG results following coadministration: both events were mild and resolved the same day. CONCLUSIONS: In this short-term, open-label study of healthy adults, coadministration of GXR and MPH did not result in significant pharmacokinetic drug-drug interactions. No unique TEAEs were observed with coadministration of GXR and MPH compared with either treatment alone.