0146 Efficacy and Safety of Single Dose of TS-142, a Novel and Potent Dual Orexin Receptor Antagonist, in Insomnia Patients

Introduction

TS-142 is a novel dual orexin receptor antagonist (DORA) developed for the treatment of insomnia. Here we report its pharmacokinetic profile in the healthy subjects and its efficacy and safety in patients with insomnia.

Methods

A phase1 study was conducted to clarify pharmacokinetic profile, in which various doses of TS-142 (1–30 mg) were orally administered once to thirty two healthy subjects. Subsequently, a phase 2a study utilizing polysomnography (PSG) was carried out in patients with primary insomnia, in which 5, 10, or 30 mg of TS-142, or placebo was randomly administered in a double-blind manner. Karolinska Sleepiness Scale (KSS) and Digit Symbol Substitution Test (DSST) were also examined in the morning after PSG.

Results

Following single administration of TS-142, plasma concentration of unchanged compound reached maximum within 2.50 h (median), and then eliminated rapidly, giving mean elimination half-life between 1.32 and 3.25 h. Twenty-three patients with insomnia completed the Phase2a study. Both latency to persistent sleep (LPS) and wake after sleep onset (WASO) were significantly improved with TS-142 at all doses, in comparison with placebo (-42, -42 and -45 for LPS [min] and -28, -35 and -55 for WASO [min] in 5, 10, 30 mg, respectively). KSS and DSST administered in the morning indicated no serious hangover effects. No serious adverse events were observed in these trials.

Conclusion

The phase 1 trial showed favorable pharmacokinetic profiles. The phase 2a trial demonstrated that TS-142 was efficacious in objective sleep onset and maintenance with minimal next-day residual effects. TS-142 was generally well tolerated in both studies.

Support

Taisho Pharmaceutical. Co., Ltd.

0004 TS-142: A Novel and Potent Dual Orexin Receptor Antagonist with Sleep-Promoting Effects in Rats

Introduction

The orexin system plays a pivotal role in regulating sleep and wakefulness, thus, orexin receptors (OX1 and OX2 receptors) have gained much attention as promising therapeutic targets for the treatment of insomnia. We synthesized a novel and potent dual orexin receptor antagonist (DORA), ORN0829 (investigation code name as TS-142), which was designed to have short-acting effects. Here we report pharmacological and pharmacokinetic profiles of ORN0829 in rats.

Methods

The antagonistic activities of ORN0829 were assessed using calcium mobilization assays. Ala-orexin A-induced [Ca2+]i response was measured with CHO-K1 cells stably expressing human/rat orexin receptor. Rats implanted the EEG/EMG electrodes were orally administrated ORN0829 at doses of 1, 3 or 10 mg/kg at the dark onset and sleep-wake stages were inspected visually. In addition, pharmacokinetic profiles of ORN0829 were investigated in rats.

Results

ORN0829 inhibited Ala-orexin A-increased [Ca2+]i response with a Kb of 0.67/0.44 nmol/L (for human/rat OX1 receptor), and with a Kb of 0.84/0.80 nmol/L (for human/rat OX2 receptor), respectively, indicating that ORN0829 is a potent DORA with no species differences. ORN0829 dose-dependently increased total sleep time and reduced sleep onset latency at doses of 1, 3 and 10 mg/kg. Importantly, the ORN0829 levels in plasma and cerebrospinal fluid rapidly reached a maximum concentration, and decreased with an elimination half-life of less than 1 h.

Conclusion

The present study indicates that ORN0829 is a novel and potent DORA with sleep-promoting effects, and that it exhibits ideal pharmacokinetic profiles (rapid absorption and short half-life) in rats. A phase 2a study of TS-142 using patients with insomnia has been completed, which is presented in a separate poster.

Support

Taisho Pharmaceutical. Co., Ltd.

Involvement of glutamatergic and GABAergic transmission in MK-801-increased gamma band oscillation power in rat cortical electroencephalograms

Hypofunction of the N-methyl-D-aspartic acid receptor (NMDAr) has been considered to play a crucial role in the pathophysiology of schizophrenia. In rodent electroencephalogram (EEG) studies, non-competitive NMDAr antagonists have been reported to produce aberrant basal gamma band oscillation (GBO), as observed in schizophrenia. Aberrations in GBO power have attracted attention as a translational biomarker for the development of novel antipsychotic drugs. However, the neuronal mechanisms as well as the pharmacological significance of NMDAr antagonist-induced aberrant GBO power have not been fully investigated. In the present study, to address the above questions, we examined the pharmacological properties of MK-801 (0.1 mg/kg)-increased basal GBO power in rat cortical EEG. Riluzole (3-10 mg/kg), a glutamate release inhibitor, reduced the MK-801-increased basal GBO power. In contrast, L-838,417 (1-3 mg/kg), an α2/3/5 subunit-selective GABAA receptor-positive allosteric modulator, enhanced the GBO increase. Antipsychotics such as haloperidol (0.05-0.3 mg/kg) and clozapine (1-10 mg/kg) dose-dependently attenuated the MK-801-increased GBO power. Likewise, LY379268 (0.3-3 mg/kg), an metabotropic glutamate 2/3 receptor (mGlu2/3 receptor) agonist, reduced the GBO increase in a dose-dependent manner, which was antagonized by an mGlu2/3 receptor antagonist LY341495. These results suggest that an increase in cortical GBO power induced by NMDAr hypofunction can be attributed to the aberrant activities of both excitatory pyramidal neurons and inhibitory interneurons in local circuits. The aberrant cortical GBO power reflecting cortical network dysfunction observed in schizophrenia might be a useful biomarker for the discovery of novel antipsychotic drugs.