Sigma-1 and dopamine D2/D3 receptor occupancy of pridopidine in healthy volunteers and patients with Huntington disease: a [18F] fluspidine and [18F] fallypride PET study.

PURPOSE: Pridopidine is an investigational drug for Huntington disease (HD). Pridopidine was originally thought to act as a dopamine stabilizer. However, pridopidine shows highest affinity to the sigma-1 receptor (S1R) and enhances neuroprotection via the S1R in preclinical studies. Using [18F] fluspidine and [18F] fallypride PET, the purpose of this study was to assess in vivo target engagement/receptor occupancy of pridopidine to the S1R and dopamine D2/D3 receptor (D2/D3R) at clinical relevant doses in healthy volunteers (HVs) and as proof-of-concept in a small number of patients with HD. METHODS: Using [18F] fluspidine PET (300 MBq, 0-90 min), 11 male HVs (pridopidine 0.5 to 90 mg; six dose groups) and three male patients with HD (pridopidine 90 mg) were investigated twice, without and 2 h after single dose of pridopidine. Using [18F] fallypride PET (200 MBq, 0-210 min), four male HVs were studied without and 2 h following pridopidine administration (90 mg). Receptor occupancy was analyzed by the Lassen plot. RESULTS: S1R occupancy as function of pridopidine dose (or plasma concentration) in HVs could be described by a three-parameter Hill equation with a Hill coefficient larger than one. A high degree of S1R occupancy (87% to 91%) was found throughout the brain at pridopidine doses ranging from 22.5 to 90 mg. S1R occupancy was 43% at 1 mg pridopidine. In contrast, at 90 mg pridopidine, the D2/D3R occupancy was only minimal (~ 3%). CONCLUSIONS: Our PET findings indicate that at clinically relevant single dose of 90 mg, pridopidine acts as a selective S1R ligand showing near to complete S1R occupancy with negligible occupancy of the D2/D3R. The dose S1R occupancy relationship suggests cooperative binding of pridopidine to the S1R. Our findings provide significant clarification about pridopidine's mechanism of action and support further use of the 45-mg twice-daily dose to achieve full and selective targeting of the S1R in future clinical trials of neurodegenerative disorders. Clinical Trials.gov Identifier: NCT03019289 January 12, 2017; EUDRA-CT-Nr. 2016-001757-41.

Modafinil and the risk of cardiovascular events: Findings from three US claims databases.

PURPOSE: This study examined the potential risk of cardiovascular (CV) events associated with modafinil and the consistency of the risk estimates across databases. METHODS: A retrospective, inception cohort design of patients who initiated treatment with modafinil between 2006 and 2008 was used in three US health care claims databases. Modafinil users were matched with nonusers. Patients were further divided into two cohorts of obstructive sleep apnea (OSA) and non-OSA (NOSA) cohorts. Endpoints of interest, including myocardial infarction (MI), stroke, CV hospitalizations, and all-cause death, were assessed using incidence rates and Cox proportional hazard ratios (HRs), adjusted for potential confounding factors. RESULTS: The cohorts included a total of 175 524 patients in MarketScan CM; 77 266-in IMS LifeLink; and 8174-in MarketScan Medicaid. No increased risk for MI in the OSA and NOSA cohorts was observed across all three databases. The risks of CV hospitalization in the OSA and NOSA cohorts were not different between the modafinil users and nonusers, except for IMS LifeLink database where the HR was lower than one in the modafinil users compared with the nonusers (HR, 0.69; 95% confidence interval [CI], 0.54 to 0.87). For OSA patients with prior stroke, an adjusted HR of 1.96 (95% CI, 1.02 to 3.76) was observed for stroke among modafinil users compared with nonusers. Among the NOSA, the HRs for all-cause death in the OSA were inconsistent across databases. CONCLUSIONS: Except for few CV outcomes, applying one common protocol generated consistent risk estimates of CV events following modafinil use across cohorts and databases.

A Phase I, Open-Label, Single-Dose Safety, Pharmacokinetic, and Tolerability Study of the Sumatriptan Iontophoretic Transdermal System in Adolescent Migraine Patients.

OBJECTIVE: To evaluate the safety, tolerability, and pharmacokinetics of sumatriptan delivered by the iontophoretic transdermal system (TDS) in adolescent patients. BACKGROUND: Since nausea can be a prominent and early symptom of migraine, nonoral treatment options are often required. Sumatriptan iontophoretic TDS is approved for the acute treatment of migraine in adults. The present study evaluates the pharmacokinetics of sumatriptan administered via the iontophoretic TDS in adolescents, contrasting the findings with historical data from adults. DESIGN: Patients aged 12-17 years (inclusive) with acute migraine were treated with sumatriptan iontophoretic TDS for 4 hours. Blood samples for pharmacokinetic profiling of sumatriptan were obtained prior to dosing and at predetermined time points covering the 12 hours postonset of treatment. Key pharmacokinetic endpoints included Cmax (peak plasma drug concentration), tmax (time to Cmax ), AUC0-∞ (area under the plasma concentration-time curve from time 0 to infinity), and t½ (terminal elimination half-life). Safety was evaluated by monitoring of adverse events in addition to laboratory and clinical assessments. RESULTS: The sample consisted of 37 patients, and 36 were included in the PK evaluable population. Cmax , tmax , AUC0-∞ , and t½ values were all similar between male and female patients and between younger (12-14 years) and older (15-17 years) adolescents. When compared with historical adult data, adolescent patients demonstrated similar systemic exposures to those observed in adults (mean Cmax 20.20 (±6.43) ng/mL in adolescents vs 21.89 (±6.15) ng/mL in adults; mean AUC0-∞ 98.1 (±28.1) ng·h/mL in adolescents vs 109.7 (±26.1) ng·h/mL in adults). All adverse events were mild or moderate, with application-site paresthesia being the most common (32%). No clinically relevant changes in laboratory values, vital signs, or electrocardiogram findings were observed. CONCLUSIONS: The iontophoretic TDS produced mean systemic exposures to sumatriptan in younger and older adolescents, in line with what was seen in adult subjects. It was generally well tolerated.

A Long-Term Safety and Tolerability Study of TV-46000 for Subcutaneous Use in Patients with Schizophrenia: A Phase 3, Randomized, Double-Blinded Clinical Trial.

BACKGROUND: TV-46000 is a long-acting subcutaneous antipsychotic (LASCA) formulation of risperidone that is approved by the United States Food and Drug Administration for the treatment of schizophrenia in adults. In the phase 3, randomized, double-blind RIsperidone Subcutaneous Extended-release (RISE) study, TV-46000 once monthly (q1m) and once every 2 months (q2m) significantly prolonged time to impending relapse compared with placebo [5.0-fold (q1m) and 2.7-fold (q2m)]. This phase 3, randomized, double-blind Safety in Humans of TV-46000 subcutaneous INjection Evaluation (SHINE) study was designed to evaluate the long-term safety, tolerability, and exposure of TV-46000 in schizophrenia. METHODS: Patients who completed RISE without relapse (rollover) or who were newly recruited (de novo) were eligible for the SHINE study. Patients were initially stabilized on oral risperidone for 12 weeks (completed in RISE for rollover, or in SHINE for de novo). Patients in the de novo cohort and patients who received placebo in RISE were randomized 1:1 in SHINE to receive TV-46000 q1m or q2m for up to 56 weeks. Primary endpoint for SHINE was frequency of reported adverse events (AEs); event rates [ER; events per 100 patient-years (PYs)] were calculated for each AE by patients upon general questioning. RESULTS: Overall, 336 patients were randomized in SHINE [TV-46000 q1m, n = 174; TV-46000 q2m, n = 162; of these, de novo, n = 109 and rollover, n = 227 (n = 172 patients were treated and n = 55 received placebo)]. A total of 334 patients were evaluated for safety [q1m, n = 172 (PY = 97.8); q2m, n = 162 (PY = 104.5)]. Proportions of patients (ER) with ≥ 1 AE and ≥ 1 treatment-related AE were 37% (180.0) and 21% (84.9) for TV-46000 q1m and 46% (157.9) and 20% (70.8) for TV-46000 q2m, respectively. Frequent treatment-related AEs [≥ 3% of patients in either group; proportion of patients (ER)] were injection site pain [q1m, 5% (24.5); q2m, 4% (22.0)] and injection site nodule [q1m, 2% (9.2); q2m, 6% (12.4)]. The proportions of patients with serious AEs was 5% for TV-46000 q1m and 7% for TV-46000 q2m; serious AEs reported for ≥ 2 patients overall were worsening schizophrenia [q1m, n = 1 (< 1%; ER, 1.02); q2m, n = 2 (1%; ER, 1.91)] and hyperglycemia [q1m, n = 1 (< 1%; ER, 1.02); q2m, n = 1 (< 1%; ER, 0.96)]. Of three reported deaths, none were related to treatment. Overall, eight patients discontinued treatment because of AEs. Similar or somewhat lower rates of AEs were reported for patients who rolled over from TV-46000 treatment compared with those who had no prior TV-46000 treatment (de novo and placebo rollover). Most AEs related to injection site reactions were mild; no patient had a severe reaction. CONCLUSION: Results from this long-term safety study add to the favorable safety profiles of TV-46000 q1m and q2m, consistent with other formulations of risperidone and previous studies with TV-46000. REGISTRATION: ClinicalTrials.gov, NCT03893825; 27 March 2019.

The United States Food and Drug Administration approved TV-46000 in April 2023 for the treatment of schizophrenia in adults. TV-46000 is a long-acting subcutaneous antipsychotic (LASCA) that uses technology that allows for the slow release of risperidone. TV-46000 is injected under the skin once monthly or once every 2 months. When people start taking TV-46000, they do not need an additional injection or oral risperidone. The Safety in Humans of TV-46000 subcutaneous INjection Evaluation (SHINE) was a clinical study in which patients with schizophrenia received TV-46000. SHINE was conducted in patients who completed the RIsperidone Subcutaneous Extended-release (RISE) study and new patients. All patients (TV-46000 once monthly, n = 162; TV-46000 once every 2 months, n = 172) received TV-46000 in SHINE to see whether safety results were the same long term compared with RISE. The proportions with more than one adverse event were 37% for TV-46000 once monthly and 46% for TV-46000 once every 2 months. The proportions with more than one adverse event related to treatment were 21% for TV-46000 once monthly and 20% for TV-46000 once every 2 months. Common adverse events related to treatment were injection site pain and small swelling. Serious adverse events were rare. None of the three reported deaths were related to treatment. Similar or lower rates of adverse events were reported for those who received TV-46000 in RISE compared with those with no prior TV-46000 treatment. The long-term safety results in SHINE were consistent with other forms of risperidone and previous studies with TV-46000.

Evaluation of Deutetrabenazine's Potential to Delay Cardiac Repolarization Using Concentration-QTc Analysis.

Deutetrabenazine (Austedo) is indicated in adults for chorea associated with Huntington disease and tardive dyskinesia. Escalating deutetrabenazine doses were administered to healthy volunteers who were cytochrome P450 2D6 extensive/intermediate metabolizers (EMs) or poor metabolizers (PMs) to determine pharmacokinetic exposure of parent drug and active metabolites (α-dihydrotetrabenazine [α-HTBZ] and ß-dihydrotetrabenazine [ß-HTBZ]), and collect corresponding electrocardiograms (ECGs) for evaluation of the cardiodynamic effect using concentration-QTc (C-QTc) modeling. Participants (12 EMs, 24 PMs) received placebo or single doses of deutetrabenazine (24, 48, and 72 mg) to achieve plasma concentrations exceeding therapeutic range in both cohorts. Pharmacokinetic samples were obtained over 72 hours after dosing and were time matched with 12-lead ECGs extracted from continuous ECG recordings. C-QTc analysis, using linear mixed-effects modeling and model selection procedure, characterized the relationship between plasma concentrations of deutetrabenazine, deuterated α-HTBZ and ß-HTBZ, and the change from baseline in QT interval corrected using Fridericia's formula. Deutetrabenazine exhibited linear kinetics, and a C-QTc model with deuterated α-HTBZ and ß-HTBZ was selected to best describe the C-QTc relationship in pooled EM and PM data. This model predicted a placebo-corrected Fridericia corrected QT interval prolongation higher than 10 milliseconds can be excluded at concentrations associated with the maximum recommended doses in both populations. Adverse events increased with higher exposure as reflected by the higher event number in the PM cohort receiving 48 and 72 mg doses. No subject discontinued due to cardiac-related adverse events and no clinically relevant ECG findings were reported. Thus, this study found that deutetrabenazine does not have a clinically relevant effect on QT prolongation at maximum recommended doses in either cytochrome P450 2D6 EMs or PMs.