Chemical synapses are the predominant neuron-to-neuron contact in the central nervous system. Presynaptic boutons of neurons contain hundreds of vesicles filled with neurotransmitters, the diffusible signaling chemicals. Changes in the number of synapses are associated with numerous brain disorders, including Alzheimer's disease and epilepsy. However, all current approaches for measuring synaptic density in humans require brain tissue from autopsy or surgical resection. We report the use of the synaptic vesicle glycoprotein 2A (SV2A) radioligand [(11)C]UCB-J combined with positron emission tomography (PET) to quantify synaptic density in the living human brain. Validation studies in a baboon confirmed that SV2A is an alternative synaptic density marker to synaptophysin. First-in-human PET studies demonstrated that [(11)C]UCB-J had excellent imaging properties. Finally, we confirmed that PET imaging of SV2A was sensitive to synaptic loss in patients with temporal lobe epilepsy. Thus, [(11)C]UCB-J PET imaging is a promising approach for in vivo quantification of synaptic density with several potential applications in diagnosis and therapeutic monitoring of neurological and psychiatric disorders.

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Identifying patients that are at high risk for seizure clusters, providing them with formal action plans and educating them about use of rescue medication for seizure clusters can help ameliorate the outcomes in this group of epilepsy patients.

Objective To evaluate the safety and efficacy of a novel formulation of midazolam administered as a single‐dose nasal spray (MDZ–NS) in the outpatient treatment of patients experiencing seizure clusters (SCs). Methods This was a phase III, randomized, double‐blind, placebo‐controlled trial (ClinicalTrials.gov NCT01390220) with patients age ≥12 years on a stable regimen of antiepileptic drugs. Following an in‐clinic test dose phase (TDP), patients entered an outpatient comparative phase (CP) and were randomized (2:1) to receive double‐blind MDZ–NS 5 mg or placebo nasal spray, administered by caregivers when they experienced an SC. The primary efficacy end point was treatment success (seizure termination within 10 minutes and no recurrence 10 minutes to 6 hours after trial drug administration). Secondary efficacy end points were proportion of patients with seizure recurrence 10 minutes to 4 hours, and time‐to‐next seizure >10 minutes after double‐blind drug administration. Safety was monitored throughout. Results Of 292 patients administered a test dose, 262 patients were randomized, and 201 received double‐blind treatment for an SC (n = 134 MDZ–NS, n = 67 placebo, modified intent‐to‐treat population). A significantly greater proportion of MDZ–NS‐ than placebo‐treated patients achieved treatment success (53.7% vs 34.4%; P = 0.0109). Significantly, fewer MDZ–NS‐ than placebo‐treated patients experienced seizure recurrence (38.1% vs 59.7%; P = 0.0043). Time‐to‐next seizure analysis showed early separation (within 30 minutes) between MDZ–NS and placebo that was maintained throughout the 24‐hour observation period (21% difference at 24 hours; P = 0.0124). Sixteen patients (5.5%) discontinued because of a treatment‐emergent adverse event (TEAE) during the TDP and none during the CP. During the CP, 27.6% and 22.4% of patients in the MDZ–NS and placebo groups, respectively, experienced ≥1 TEAE. Significance MDZ–NS was superior to placebo in providing rapid, sustained seizure control when administered to patients experiencing an SC in the outpatient setting and was associated with a favorable safety profile.

Objective To evaluate safety‐ and seizure‐related outcomes with repeated intermittent use of a novel formulation of midazolam administered as a single‐dose nasal spray (MDZ‐NS) in the outpatient treatment of patients experiencing seizure clusters (SCs). Methods In this open‐label extension trial (ClinicalTrials.gov NCT01529034), patients aged ≥12 years and on a stable regimen of antiepileptic drugs who completed the original phase III, randomized controlled trial were enrolled. Caregivers administered MDZ‐NS 5 mg when patients experienced SCs; a second dose could be given if seizures did not terminate within 10 minutes or recurred within 10 minutes‐6 hours. Patients were monitored for treatment‐emergent adverse events (TEAEs) throughout, and the main seizure‐related outcome was treatment success, defined as seizure termination within 10 minutes and no recurrence 10 minutes‐6 hours after drug administration. Results Of 175 patients enrolled, 161 (92.0%) received ≥1 MDZ‐NS dose, for a total of 1998 SC episodes. Median time spent by patients in the trial was 16.8 months (range = 1‐55.7 months). TEAEs were experienced by 40.4% of patients within 2 days of drug administration and 57.1% overall. TEAEs reported by most patients (within 2 days and overall) were nasal discomfort (12.4%) and somnolence (9.3%). One patient each discontinued due to treatment‐related nasal discomfort and somnolence. There were no patients with treatment‐related respiratory depression, and none with TEAEs indicative of drug abuse or dependence. Treatment success criteria were met in 55% (1108/1998) of SC episodes after administration of a single 5‐mg dose and in 80.2% (617/769) with the second dose. Treatment success was consistent over treated episode number. Significance Repeated, intermittent, acute treatment of patients experiencing SCs with MDZ‐NS in the outpatient setting was well tolerated over an extended period, with maintenance of efficacy suggesting lack of development of tolerance.