Population Pharmacokinetics and Exposure-Response Analyses for the Most Frequent Adverse Events Following Treatment With Lemborexant, an Orexin Receptor Antagonist, in Subjects With Insomnia Disorder

Emerging and upcoming therapies in insomnia

Insomnia, commonly treated with benzodiazepine (BZD) receptor agonists, presents challenges due to associated serious side effects such as abuse and dependence. To address these concerns, many researches have been conducted to develop and advance both pharmacological and non-pharmacological interventions. Dual orexin receptor antagonists (DORAs), which include suvorexant, daridorexant and lemborexant, have recently been approved by United States Food and Drug Administration (US FDA) as a novel pharmacotherapeutic alternative. Unlike BZD receptor agonists that act as positive allosteric modulators of the gamma-aminobutyric acid type A subunit alpha 1 receptor, DORAs function by binding to both orexin receptor types 1 and 2, and inhibiting the action of the wake-promoting orexin neuropeptide. These drugs induce normal sleep without sleep stage change, do not impair attention and memory performance, and facilitate easier awakening. However, more real-world safety information is needed. Selective orexin-2 receptor antagonists (2-SORAs) is under clinical developments. This review provides an overview of the mechanism of action in relation to insomnia, pharmacokinetics, efficacy and safety information of DORAs and SORA. According to insomnia management guidelines, the first-line treatment for chronic insomnia is cognitive behavioral therapy for insomnia (CBT-I). Although it has proven effective in improving sleep-related quality of life, it has several restrictions limitations due to a face-to-face format. Recently, prescription digital therapy such as Somryst® was approved by US FDA. Somryst®, a smartphone app-based CBT-I, demonstrated meaningful responses in patients. However, digital limitations may impact scalability. Overall, these developments offer promising alternatives for insomnia treatment, emphasizing safety, efficacy, and accessibility.

Exposure-Response Analyses of Polysomnography and Subjective Sleep Efficacy End Points From the Phase 3 Trials of Lemborexant, a Dual Orexin Receptor Antagonist for the Treatment of Insomnia

This report describes polysomnography and sleep diary exposure-response analyses from Study E2006-G000-304 (Study 304), a 1-month trial of 5- or 10-mg lemborexant, zolpidem, or placebo; and Study E2006-G000-303 (Study 303), a 6-month trial of 5- or 10-mg lemborexant or placebo. Studies 304 and 303 included 1006 (86%) and 956 (68%) (female) participants, respectively; >40% were ≥65 years, with individual lemborexant exposures derived from a previously described pharmacokinetic model. Linear mixed-effects analyses of polysomnography: latency to persistent sleep (LPS), sleep efficiency (SE), and wake after sleep onset (WASO) quantified the change from baseline given lemborexant exposure, time, and covariates, guided by consensus recommendations regarding clinical significance. A small impact of sex, body weight, and race was predicted for LPS and SE, irrespective of treatment. Effect of age on LPS was small; baseline SE was estimated to be 8% higher for a 50-year-old versus an 80-year-old, decreasing to 6% by 1 month. Baseline WASO was 13 minutes longer for Black versus White subjects, corresponding to a 5-minute lower change from baseline at the end of the study. For subjective end points, the statistically significant covariate effects for age, sex, and race were not deemed therapeutically relevant, likely reflecting physiologic sleep pattern changes across age and study subgroups. Both polysomnography and subjective analyses indicated clinically meaningful differences from baseline for both lemborexant treatments, with effects being greater for 10-mg versus 5-mg lemborexant, while indicating that covariate-specific lemborexant dose adjustments are not warranted.

Targeting Orexin Receptors for the Treatment of Insomnia: From Physiological Mechanisms to Current Clinical Evidence and Recommendations

After a detailed description of orexins and their roles in sleep and other medical disorders, we discuss here the current clinical evidence on the effects of dual (DORAs) or selective (SORAs) orexin receptor antagonists on insomnia with the aim to provide recommendations for their further assessment in a context of personalized and precision medicine. In the last decade, many trials have been conducted with orexin receptor antagonists, which represent an innovative and valid therapeutic option based on the multiple mechanisms of action of orexins on different biological circuits, both centrally and peripherally, and their role in a wide range of medical conditions which are often associated with insomnia. A very interesting aspect of this new category of drugs is that they have limited abuse liability and their discontinuation does not seem associated with significant rebound effects. Further studies on the efficacy of DORAs are required, especially on children and adolescents and in particular conditions, such as menopause. Which DORA is most suitable for each patient, based on comorbidities and/or concomitant treatments, should be the focus of further careful research. On the contrary, studies on SORAs, some of which seem to be appropriate also in insomnia in patients with psychiatric diseases, are still at an early stage and, therefore, do not allow to draw definite conclusions.

Efficacy and safety of lemborexant over 12 months in Asian adults with insomnia disorder

Study objectives

Lemborexant (LEM) is a dual orexin receptor antagonist approved for treating adults with insomnia. We analyzed the efficacy (subjective sleep outcomes) and safety of LEM over 12 months in the subgroup of Asian subjects from Study E2006-G000-303 (Study 303).

Methods

Study 303 was a 12-month, randomized, placebo-controlled (first 6 months), double-blind, parallel-group, phase 3 study of adults with insomnia disorder. During the 6-month Period 1, subjects were randomized (1:1:1) to placebo, LEM 5 mg (LEM5), or LEM 10 mg (LEM10); LEM subjects continued treatment in the following 6-month Period 2. Outcome measures included subject-reported (subjective) sleep onset latency (sSOL), sleep efficiency (sSE), wake after sleep onset (sWASO), total sleep time (sTST), Insomnia Severity Index (ISI), and Patient Global Impression–Insomnia version (PGI-I). Treatment-emergent adverse events (TEAEs) were assessed.

Results

Overall, 178 Asian subjects (Japanese, n = 161; Chinese, n = 4; other Asian, n = 13) were included. Greater decreases in sSOL and sWASO and increases in sSE and sTST from baseline were observed with LEM vs placebo at 6 months; LEM benefits were sustained through 12 months. Greater decreases in ISI total score were seen with LEM vs placebo at 6 months; improvements from baseline with LEM continued through 12 months. For each PGI-I item, LEM-treated subjects had more positive medication effects than placebo-treated subjects at 6 months; these effects were maintained with LEM in Period 2. TEAEs were generally mild to moderate.

Conclusions

LEM improved subjective sleep parameters and was well-tolerated in Asian subjects with insomnia disorder over 12 months.

Clinical trial registration

ClinicalTrials.gov, NCT02952820; ClinicalTrialsRegister.eu, EudraCT Number 2015-001463-39.

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Lemborexant improved subjective sleep measures and provided positive medication effects over 6 months versus placebo.

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Benefits of lemborexant were sustained over 12 months.

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Few (∼3%) lemborexant-treated Asian subjects discontinued treatment because of adverse events.

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Lemborexant can potentially treat Asian persons with insomnia effectively, with fewer side effects than other medications.

Population pharmacokinetic modeling of daridorexant, a novel dual orexin receptor antagonist

The analysis aimed at identifying subject-specific characteristics (covariates) influencing exposure to daridorexant and quantification of covariate effects to determine clinical relevance. Data from 13 phase I, two phase II, and two phase III studies were pooled to develop a population pharmacokinetic model describing daridorexant concentration over time. Covariate effects were quantified based on model predictions. A two-compartment model with dose-dependent bioavailability, absorption lag time, linear absorption, and nonlinear elimination described the data best. Statistically significant covariates were food status on absorption (lag time and rate constant), time of drug administration (morning, bedtime) on absorption rate constant, lean body weight on central volume of distribution and elimination, fat mass on peripheral volume of distribution and intercompartmental drug transfer, and age and alkaline phosphatase on elimination. Age, lean body weight, fat mass, and alkaline phosphatase influence exposure (area under the curve, time of maximum concentration after dose administration, maximum plasma concentration, and next-morning concentration) to a limited extent, that is, less than 20% difference from a typical subject. Morning administration is not relevant for daridorexant use by insomnia patients. The food effect with simultaneous intake of a high-fat, high-calorie food is an extreme-case scenario unlikely to occur in clinical practice. Body composition, alkaline phosphatase, and age showed clinically negligible effects on exposure to daridorexant. Lean body weight and fat mass described the pharmacokinetics of daridorexant better than other body size descriptors (body weight, height, body mass index), suggesting a convenient physiological alternative to reduce the number of covariates in population pharmacokinetic models. The results indicate that differences between subjects do not require dose adjustments.

Cost-effectiveness analysis of lemborexant for treating insomnia in Japan: a model-based projection, incorporating the risk of falls, motor vehicle collisions, and workplace accidents

BACKGROUND

Lemborexant has demonstrated statistically significant improvements in sleep onset and sleep maintenance compared with placebo and zolpidem tartrate extended release, measured both objectively using polysomnography and subjectively using sleep diaries, in the phase 3 clinical trial SUNRISE 1. This study evaluated the cost-effectiveness of lemborexant compared with suvorexant, zolpidem immediate release (IR), and untreated insomnia.

METHODS

A decision-tree model was developed for falls, motor vehicle collisions, and workplace accidents associated with insomnia and insomnia treatments from a Japanese healthcare perspective and with a 6-month time horizon. The model extracted subjective sleep onset latency treatment responses and disutility values for non-responders from SUNRISE 1. Cost-effectiveness was assessed using incremental cost per quality-adjusted life year (QALY) gained. One-way and probabilistic sensitivity analyses were conducted to evaluate the impact of parameter uncertainty on the results.

RESULTS

In the base-case analysis, the mean estimated QALYs for lemborexant, suvorexant, zolpidem-IR, and untreated insomnia were 0.4220, 0.4204, 0.4113, and 0.4163, and expected medical costs were JPY 34 034, JPY 38 371, JPY 38 139, and JPY 15 383, respectively. Lemborexant saved JPY 4337 and JPY 4105 compared with suvorexant or zolpidem-IR, respectively, while conferring QALY benefits. The incremental cost-effectiveness ratio (ICER) of lemborexant compared with that of untreated insomnia was JPY 3 220 975 /QALY. Lemborexant was dominant over suvorexant and zolpidem-IR and was cost-effective when compared with untreated insomnia. Sensitivity analyses supported the results' robustness.

CONCLUSIONS

In a Japanese clinical practice setting, lemborexant may represent a better investment for treating insomnia in the healthcare system in Japan.

Hypocretins (orexins): The ultimate translational neuropeptides

The hypocretins (Hcrts), also known as orexins, are two neuropeptides produced exclusively in the lateral hypothalamus. They act on two specific receptors that are widely distributed across the brain and involved in a myriad of neurophysiological functions that include sleep, arousal, feeding, reward, fear, anxiety and cognition. Hcrt cell loss in humans leads to narcolepsy with cataplexy (narcolepsy type 1), a disorder characterized by intrusions of sleep into wakefulness, demonstrating that the Hcrt system is nonredundant and essential for sleep/wake stability. The causal link between Hcrts and arousal/wakefulness stabilisation has led to the development of a new class of drugs, Hcrt receptor antagonists to treat insomnia, based on the assumption that blocking orexin-induced arousal will facilitate sleep. This has been clinically validated: currently, two Hcrt receptor antagonists are approved to treat insomnia (suvorexant and lemborexant), with a New Drug Application recently submitted to the US Food and Drug Administration for a third drug (daridorexant). Other therapeutic applications under investigation include reduction of cravings in substance-use disorders and prevention of neurodegenerative disorders such as Alzheimer's disease, given the apparent bidirectional relationship between poor sleep and worsening of the disease. Circuit neuroscience findings suggest that the Hcrt system is a hub that integrates diverse inputs modulating arousal (e.g., circadian rhythms, metabolic status, positive and negative emotions) and conveys this information to multiple output regions. This neuronal architecture explains the wealth of physiological functions associated with Hcrts and highlights the potential of the Hcrt system as a therapeutic target for a number of disorders. We discuss present and future possible applications of drugs targeting the Hcrt system for the treatment of circuit-related neuropsychiatric and neurodegenerative conditions.

Efficacy and safety of lemborexant in adults with insomnia: comparing Japanese and non-Japanese subgroups from the global, phase 3, randomized, double-blind, placebo-controlled SUNRISE 2 study

STUDY OBJECTIVE

Whether there are racial differences in the efficacy/safety of hypnotics has not been sufficiently investigated. We aimed to evaluate the efficacy/safety of lemborexant 5 mg and lemborexant 10 mg vs placebo once daily in a subset of Japanese patients with insomnia and to compare the results with those of non-Japanese patients.

METHODS

This subanalysis reports the results of the first 6 months (period 1, placebo-controlled) of SUNRISE 2, a 12-month, global, randomized, double-blind, phase 3 study. Changes in patient-reported sleep onset latency, patient-reported sleep efficiency, and patient-reported wake after sleep onset with lemborexant 5 mg or lemborexant 10 mg vs placebo were evaluated. Treatment-emergent adverse events were evaluated for safety.

RESULTS

In total, 949 patients were randomized (Japanese, n = 161; non-Japanese, n = 788). Groups were balanced at baseline except for the male/female ratio (P = .0002) and body mass index (P < .0001) in the Japanese vs non-Japanese subgroups. Overall, the efficacy and safety of lemborexant were similar between subgroups. In the Japanese subgroup, the subjective sleep onset latency change from baseline was significant after 7 nights and 6 months with lemborexant 10 mg vs placebo, the subjective sleep efficiency change from baseline was significant after 7 nights with lemborexant 10 mg vs placebo, and the subjective wake after sleep onset change from baseline was significant at 6 months with lemborexant 5 mg vs placebo. The incidence and severity of treatment-emergent adverse events were consistent between both subgroups.

CONCLUSIONS

Lemborexant 5 mg and 10 mg improved sleep onset and sleep maintenance over 6 months and was well-tolerated in both the Japanese and non-Japanese patients. The safety profiles of lemborexant 5 mg and 10 mg were consistent between the subgroups.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Long-term Study of Lemborexant in Insomnia Disorder (SUNRISE 2); URL: https://clinicaltrials.gov/ct2/show/NCT02952820; Identifier: NCT02952820; and Registry: ClinicalTrialsRegister.eu; Identifier: 2015-001463-39.

Evaluating lemborexant for the treatment of insomnia

INTRODUCTION

Insomnia is a complex sleep disorder that compromises quality of life and affects approximately 10% of the general population. Insomnia, defined as trouble initiating or maintaining sleep associated with impaired daytime function or distress, is treated using a comprehensive approach comprised of cognitive behavioral therapy and pharmacotherapy. Lemborexant, a dual orexin receptor antagonist, is a new pharmacotherapeutic option recently approved for the treatment of insomnia.

AREAS COVERED

Here, the authors describe lemborexant, assess its efficacy and safety profile in clinical trials, and evaluate its role in the current insomnia treatment landscape.

EXPERT OPINION

Lemborexant may offer an improved treatment option compared with other pharmacotherapies for insomnia because it is effective both over the long term and over a wide range of outcome measures. Importantly, lemborexant improves latency to sleep onset and sleep maintenance and is able to help people who experience early morning awakenings. Safety data reveal that lemborexant has minimal residual effects on morning alertness or next day function, and that patients are able to respond to an external auditory stimulus in the middle of the night. In conclusion, lemborexant represents a new, effective, and well-tolerated medication for patients with insomnia.

Physiologically-based pharmacokinetic modeling to predict drug interactions of lemborexant with CYP3A inhibitors

Lemborexant, a recently approved dual orexin receptor antagonist for treatment of adults with insomnia, is eliminated primarily by cytochrome P450 (CYP)3A metabolism. The recommended dose of lemborexant is 5 mg once per night, with a maximum recommended dose of 10 mg once daily. A physiologically-based pharmacokinetic (PBPK) model for lemborexant was developed and applied to integrate data obtained from in vivo drug-drug interaction (DDI) assessments, and to further explore lemborexant interaction with CYP3A inhibitors and inducers. The model predictions were in good agreement with observed pharmacokinetic data and with DDI results from clinical studies with CYP3A inhibitors, itraconazole and fluconazole. The model further predicted that DDI effects of weak CYP3A inhibitors (fluoxetine and ranitidine) are weak, and effects of moderate inhibitors (erythromycin and verapamil) are moderate. Based on the PBPK simulations and clinical efficacy and safety data, the maximum daily recommended lemborexant dose when administered with weak CYP3A inhibitors is 5 mg; co-administration of moderate and strong inhibitors should be avoided except in countries where 2.5 mg has been approved.

Effect of severe renal impairment on pharmacokinetics, safety, and tolerability of lemborexant

The primary aim of this study was to examine the effect of severe renal impairment (SRI) on the pharmacokinetics of lemborexant, a dual orexin receptor antagonist indicated for the treatment of insomnia. A phase 1 multicenter, single‐dose, open‐label, parallel‐group study was conducted in subjects with SRI not requiring dialysis (estimated glomerular filtration rate 15–29 ml/min/1.73 m²; n = 8) compared with demographically matched healthy subjects with normal renal function (n = 8). Plasma levels of lemborexant and its metabolites were measured over 240 h following a single oral 10‐mg dose administered in the morning. Relative to subjects with normal renal function, lemborexant maximum plasma concentration (C_max) was similar, whereas area under the plasma concentration–time curve from zero to time of last quantifiable concentration (AUC_(0‐t)) and AUC from zero to infinity (AUC_(0‐inf)) were about 1.5‐fold higher in subjects with SRI. The geometric mean ratios (90% confidence interval) were 104.8 (77.4–142.0), 150.5 (113.2–200.3), and 149.8 (113.1–198.6) for C_max, AUC_(0‐t), and AUC_(0‐inf), respectively. In both groups, the median lemborexant time to C_max (t_max) was 1 h, and the mean unbound fraction of lemborexant was ~7%. For the M4, M9, and M10 metabolites, C_max was reduced ~20% and exposure (AUC_(0‐t) and AUC_(0‐inf)) was ~1.4‐ to 1.5‐fold higher in subjects with SRI versus healthy subjects; t_max was delayed ~1.5–2 h for M4 and M10. All treatment‐emergent adverse events were mild or moderate. Lemborexant pharmacokinetics were not sufficiently altered to warrant a dose adjustment for subjects with renal impairment.

Evaluation of the CYP3A and CYP2B6 Drug-Drug Interaction Potential of Lemborexant

Lemborexant is approved for treating insomnia and is under investigation for treating irregular sleep‐wake rhythm disorder. Based on in vitro drug‐drug interaction (DDI) characteristics, phase 1, open‐label DDI studies were conducted to evaluate lemborexant's cytochrome P450 3A (CYP3A) and CYP2B6 interaction potential. Interactions between lemborexant 10 mg and strong and moderate CYP3A inhibitors (itraconazole and fluconazole), a strong CYP3A inducer (rifampin), and CYP3A (midazolam) and CYP2B6 substrates (bupropion) were evaluated. Coadministration of lemborexant with itraconazole or fluconazole resulted in 1.4‐ to 1.6‐fold and 3.7‐ to 4‐fold increases in lemborexant maximum observed concentration (C_max) and area under the concentration‐time curve from zero time extrapolated to infinity (AUC_0‐inf), respectively. Coadministration of lemborexant with rifampin resulted in >90% decreases in lemborexant C_max and AUC_0‐inf. Midazolam exposure was not affected. Coadministration of lemborexant with bupropion resulted in 49.9% and 45.5% decreases in S‐bupropion C_max and AUC_0‐inf, respectively.Comparison of estimated exposures for patients in phase 3 trials who were/were not receiving concomitant weak CYP3A inhibitors substantiated the DDI pharmacokinetic findings. Lemborexant was generally well tolerated in the phase 1 studies. In summary, lemborexant does not affect the pharmacokinetics of CYP3A substrates and has potential to induce CYP2B6. Consistent with in vitro findings, moderate and strong CYP3A inhibitors and inducers affected the pharmacokinetics of lemborexant; hence, patients taking lemborexant 5 or 10 mg should avoid coadministration with moderate and strong CYP3A inhibitors and inducers.

Population Pharmacokinetics and Exposure-Response Analyses for the Most Frequent Adverse Events Following Treatment With Lemborexant, an Orexin Receptor Antagonist, in Subjects With Insomnia Disorder

Lemborexant is a novel orexin receptor antagonist approved in the United States and Japan for the treatment of insomnia. This article describes the population pharmacokinetics (PK) of lemborexant and the relationship of its daily steady-state exposure (Cav,ss ) to the probability of most frequent treatment-emergent adverse events (TEAEs). The 12 230-observation, 1892-subject PK data set included data from 12 clinical studies with predominantly female subjects (66%) ranging in age from 18 to 88 years and from 37 to 168 kg in body weight. The 1664-subject exposure-response data set included data from 3 late-stage studies. Lemborexant pharmacokinetics were described by a 3-compartment model with combined first- and zero-order absorption with lag time and linear elimination. Oral clearance decreased with increasing body mass index (exponent, -0.428), increasing alkaline phosphatase levels (exponent, -0.118), and was 26% lower in the elderly (≥65 years). Across the adverse event analysis, the frequency of subjects experiencing TEAEs during active treatment ranged from approximately 3% to 8%, in the range estimated for placebo. With and without adjustment for age, lemborexant exposure (Cav,ss ) was not a clinically meaningful linear predictor of the probability of specific TEAEs: somnolence, nasopharyngitis, flu/influenza, urinary tract infection, upper respiratory tract infection, or headache. Given the small effect sizes of covariates of the PK model and a low degree of association of lemborexant TEAEs and exposure over the range of phase 3 (therapeutic) 5- and 10-mg doses, lemborexant can be safely administered without the need for dose adjustment.