Review of the histamine system and the clinical effects of H1 antagonists: Basis for a new model for understanding the effects of insomnia medications

Comparative short-term safety and efficacy of hypnotics: A quantitative risk-benefit analysis

Several professional societies have provided recommendations for prescribing medications for insomnia. None has provided an integrative analysis that concurrently quantifies safety and efficacy (e.g., risk-benefit ratios). This represents an important gap for informing clinician decision-making. Accordingly, the aim of the present review is to provide such an analysis for five classes of sleep-promoting medications. Adverse event data values were extracted from the most recent FDA-approved package inserts and converted to an integer before being placebo-adjusted and standardized as a rate per 1000 (AEr). Efficacy data, pre-to-post self-reported data for active and placebo conditions were acquired from pivotal trials identified in "white papers" and systematic reviews/meta-analyses. Weighted effect sizes were calculated for subjective sleep latency, wake time after sleep onset and total sleep time, and then were averaged by medication class for each sleep continuity variable. Overall efficacy was represented by a single variable, SWT (sleep latency + wake time after sleep onset + total sleep time). Risk-benefit was represented using a simple ratio value. For safety, it was found that melatonin receptor agonists had the lowest adverse event rate (AEr = 43.1), and non-benzodiazepine benzodiazepine receptor agonists had the highest rate (AEr = 255.0). For efficacy, it was found that the pre-to-post placebo adjusted effect sizes were largest for benzodiazepines (effect size = 1.94) and smallest for melatonin receptor agonists (effect size = 0.109). For risk-benefit, histamine antagonist had the most favourable profile (risk-benefit = 69.5), while melatonin receptor agonist had the least favourable profile (risk-benefit = 395.7). Overall, the combined metric for risk-benefit suggests that treatment with a histamine antagonist is optimal and potentially represents the best first-line therapy for the medical management of insomnia.

Binding characteristics of the doxepin E/Z-isomers to the histamine H1 receptor revealed by receptor-bound ligand analysis and molecular dynamics study

Doxepin is an antihistamine and tricyclic antidepressant that binds to the histamine H1 receptor (H1R) with high affinity. Doxepin is an 85:15 mixture of the E- and Z-isomers. The Z-isomer is well known to be more effective than the E-isomer, whereas based on the crystal structure of the H1R/doxepin complex, the hydroxyl group of Thr1123.37 is close enough to form a hydrogen bond with the oxygen atom of the E-isomer. The detailed binding characteristics and reasons for the differences remain unclear. In this study, we analyzed doxepin isomers bound to the receptor following extraction from a purified H1R protein complexed with doxepin. The ratio of the E- and Z-isomers bound to wild-type (WT) H1R was 55:45, indicating that the Z-isomer was bound to WT H1R with an approximately 5.2-fold higher affinity than the E-isomer. For the T1123.37V mutant, the E/Z ratio was 89:11, indicating that both isomers have similar affinities. Free energy calculations using molecular dynamics (MD) simulations also reproduced the experimental results of the relative binding free energy differences between the isomers for WT and T1123.37V. Furthermore, MD simulations revealed that the hydroxyl group of T1123.37 did not form hydrogen bonds with the E-isomer, but with the adjacent residues in the binding pocket. Analysis of the receptor-bound doxepin and MD simulations suggested that the hydroxyl group of T1123.37 contributes to the formation of a chemical environment in the binding pocket, which is slightly more favorable for the Z-isomer without hydrogen bonding with doxepin.

Sleep medicines are often prescribed for older adults (≥75 years) without appropriate dosing instructions: A nationwide retrospective register study in Finland

BACKGROUND

Sleep medicines should be prescribed cautiously, accompanied by instructions that ensure appropriate use and reduce risks. This is especially important for older adults, for whom many of these medicines are classified as potentially inappropriate medicines.

METHODS

We investigated the use and appropriateness of dosing instructions for sleep medicines (described in the Finnish National Current Care Guideline for Insomnia) prescribed for older adults (≥75 years) and dispensed with instruction label in pharmacies. The retrospective reimbursement register data for year 2020 by the Social Insurance Institution of Finland was used as the data source (1,080,843 purchases by 143,886 individuals of which 565,228 purchases were pharmacy dispenses). The appropriateness of the pharmacy dosing instructions containing keyword(s) referring to insomnia treatment was examined according to the prescribed dose, time of intake, frequency of use, and warnings/remarks. A random sample of 1000 instructions was used to manually analyze the phrasing and appropriateness.

OUTCOMES

We focused our analysis on 58.1% (328,285 purchases by 87,396 individuals) of the pharmacy dispenses, which contained dosing instructions referring insomnia treatment. Of these, zopiclone and mirtazapine were the most prescribed drugs (134,631 and 112,463 purchases, respectively). Dose and time of intake were specified in most of the instructions (98.4% and 83.4%, respectively), whereas frequency of use was specified in 57.3%. A small percentage of the instructions included warnings/remarks (2.8%). Overall, only 2.1% of the instructions contained information about a single dose, time of intake, temporary use, and warnings/remarks and were thus defined as sufficient. Notably, 47.7% (n = 515,615) of all the purchases in our dataset were dispensed via automated multi-dose dispensing systems, which is aimed for long-term treatment.

INTERPRETATION

It is common to prescribe sleep medicines for older adults without appropriate dosing instructions, particularly excluding warnings against long-term, regular use. Actions to change the current prescribing practices are warranted.

Insomnia medications: History, characteristics, and guidelines for optimal use in clinical practice

This article reviews the history of insomnia pharmacotherapy, documenting the evolution that has occurred over time in the increasing availability of medications with novel mechanisms of action that more specifically target the neural systems that modulate sleep/wake function. This evolution provides an increasing capacity to improve the effectiveness of insomnia pharmacotherapy by allowing the selection of medications that specifically target the particular type of sleep difficulty present in each patient. As a result, they can achieve a therapeutic effect with fewer effects on aspects of brain function other than those needed to achieve benefit, thereby minimising adverse effects. The accumulated evidence-base is such that it can serve as the basis for a personalised insomnia pharmacotherapy paradigm. Here we outline a set of best-practice recommendations for how to carry out optimised personalised insomnia pharmacotherapy based on that evidence base in the hope that it will improve the treatment delivered to the many individuals suffering from insomnia.

Sophorolipid inhibits histamine-induced itch by decreasing PLC/IP3R signaling pathway activation and modulating TRPV1 activity

Biosurfactants are attracting much interest due to their potential application as therapeutic agents in the medical and cosmetic field. Previous studies have demonstrated that biosurfactant such as sophorolipid (SL) exhibits immunomodulatory effects. In this article, we found the potential of sophorolipid for inhibiting histamine-induced itch and preliminarily explored its molecular basis. First, behavioral tests indicated that SL can remit the histamine-induced scratching behaviors of mice. Second, SL can suppress the the calcium influx induced by histamine, HTMT and VUF8430 in HaCaT cells. RT-PCR analysis showed that the histamine-induced upregulation of mRNA levels of phospholipase Cγ1, 1,4,5-trisphosphate receptor (IP3R), and protein kinase Cα can be inhibted by SL, suggesting that SL may impede the PLC/IP3R signaling pathway activated by histamine. In further tests, the capsaicin-induced calcium influx can also be inhibited by SL. The immunofluorescence and molecular docking analysis indicated that SL acts as an inhibitor of transient receptor potential vanilloid-1 (TRPV1) activation to decrease calcium influx against stimuli. In summary, these results revealed that SL may inhibit histamine-induced itch by decreasing PLC/IP3R signaling pathway activation and modulating TRPV1 activity. This paper indicates that SL can be a useful treatment for histamine-dependent itch.

Off-label low dose amitriptyline for insomnia disorder: Patient-reported outcomes

PURPOSE

Low dose amitriptyline is prescribed off-label to improve sleep maintenance in patients with insomnia disorder. Data on treatment outcomes are limited. We aimed to assess patient-reported treatment effect and side effects of low dose amitriptyline for insomnia in routine care data.

METHODS

Cross-sectional study: Seven hundred fifty-two consecutive patients with insomnia disorder having sleep maintenance problems were treated in an outpatient sleep clinic with low dose amitriptyline (10-20 mg based on self-titration). Treatment was intended to improve sleep maintenance. Before the planned follow-up consultation (approximately 6 weeks after start treatment) patients completed an online treatment evaluation questionnaire. Treatment (dose, adherence), sleep, fatigue, satisfaction and side effects were assessed by multiple-choice questions with room for free-text elaboration.

RESULTS

53.7% of the patients reported to use amitriptyline up to 10 mg/day, 42.9% used a self-increased dose of mostly 20 mg/day, while 3.5% had discontinued treatment. 73.9% of the total study population reported improvement of sleep maintenance, 31.3% improved sleep onset, 35.2% improved daytime fatigue, and 45.8% reported to be (very) satisfied with treatment results. 66.1% reported at least one side effect. The reported side effects were generally the already known side effects of amitriptyline.

CONCLUSION

These patient-reported outcomes support the clinical observations that low dose amitriptyline improves sleep maintenance on the short term and that it is generally well tolerated. This further justifies randomized controlled trials in patients with insomnia disorder and sleep maintenance problems to assess the effectiveness and safety of low dose amitriptyline on the short and long term.

Recent hospitalization and risk of antidepressant initiation in people with Parkinson's disease

BACKGROUND

People with Parkinson's disease (PD) are more likely to be hospitalized and initiate antidepressant use compared to people without PD. It is not known if hospitalization increases the risk of antidepressant initiation. We studied whether a recent hospitalization associates with antidepressant initiation in people with PD.

METHODS

A nested case-control study within the nationwide register-based FINPARK cohort which includes community-dwelling Finnish residents diagnosed with PD between years 1996 and 2015 (N = 22,189) was conducted. Initiation of antidepressant use after PD diagnosis was identified from Prescription Register with 1-year washout period (cases). One matched non-initiator control for each case was identified (N = 5492 age, sex, and time since PD diagnosis-matched case-control pairs). Hospitalizations within the 14 day-period preceding the antidepressant initiation were identified from the Care Register for Health Care.

RESULTS

The mean age at antidepressant initiation was 73.5 years with median time since PD diagnosis 2.9 years. Selective serotonin reuptake inhibitors (48.1%) and mirtazapine (35.7%) were the most commonly initiated antidepressants. Recent hospitalization was more common among antidepressant initiators than non-initiators (48.3 and 14.3%, respectively) and was associated with antidepressant initiation also after adjusting for comorbidities and use of medications during the washout (adjusted OR, 95% CI 5.85, 5.20-6.59). The initiators also had longer hospitalizations than non-initiators. PD was the most common main discharge diagnosis among both initiators (54.6%) and non-initiators (28.8%). Discharge diagnoses of mental and behavioral disorders and dementia were more common among initiators.

CONCLUSIONS

Hospitalisation is an opportunity to identify and assess depressive symptoms, sleep disorders and pain, which may partially explain the association. Alternatively, the indication for antidepressant initiation may have led to hospitalisation, or hospitalisation to aggravation of, e.g., neuropsychiatric symptoms leading to antidepressant initiation.

HNMT Upregulation Induces Cancer Stem Cell Formation and Confers Protection against Oxidative Stress through Interaction with HER2 in Non-Small-Cell Lung Cancer

Background: The treatment of non-small-cell lung cancer (NSCLC) involves platinum-based chemotherapy. It is typically accompanied by chemoresistance resulting from antioxidant properties conferred by cancer stem cells (CSCs). Human epidermal growth factor receptor 2 (HER2) enhances CSCs and antioxidant properties in cancers, including NSCLC. Methods: Here, we elucidated the role of histamine N-methyltransferase (HNMT), a histamine metabolism enzyme significantly upregulated in NSCLC and coexpressed with HER2. HNMT expression in lung cancer tissues was determined using quantitative reverse transcription PCR (RT-qPCR). A publicly available dataset was used to determine HNMT’s potential as an NSCLC target molecule. Immunohistochemistry and coimmunoprecipitation were used to determine HNMT–HER2 correlations and interactions, respectively. HNMT shRNA and overexpression plasmids were used to explore HNMT functions in vitro and in vivo. We also examined miRNAs that may target HNMT and investigated HNMT/HER2’s role on NSCLC cells’ antioxidant properties. Finally, how HNMT loss affects NSCLC cells’ sensitivity to cisplatin was investigated. Results: HNMT was significantly upregulated in human NSCLC tissues, conferred a worse prognosis, and was coexpressed with HER2. HNMT depletion and overexpression respectively decreased and increased cell proliferation, colony formation, tumorsphere formation, and CSCs marker expression. Coimmunoprecipitation analysis indicated that HNMT directly interacts with HER2. TARGETSCAN analysis revealed that HNMT is a miR-223 and miR-3065-5p target. TBHp treatment increased HER2 expression, whereas shHNMT disrupted the Nuclear factor erythroid 2-related factor 2 (Nrf2)/ hemeoxygenase-1 (HO-1)/HER2 axis and increased reactive oxygen species accumulation in NSCLC cells. Finally, shHNMT sensitized H441 cells to cisplatin treatment in vitro and in vivo. Conclusions: Therefore, HNMT upregulation in NSCLC cells may upregulate HER2 expression, increasing tumorigenicity and chemoresistance through CSCs maintenance and antioxidant properties. This newly discovered regulatory axis may aid in retarding NSCLC progression and chemoresistance.

The Role of the Central Histaminergic System in Behavioral State Control

Histamine is a small monoamine signaling molecule that plays a role in many peripheral and central physiological processes, including the regulation of wakefulness. The tuberomammillary nucleus is the sole neuronal source of histamine in the brain, and histamine neurons are thought to promote wakefulness and vigilance maintenance - under certain environmental and/or behavioral contexts - through their diffuse innervation of the cortex and other wake-promoting brain circuits. Histamine neurons also contain a number of other putative neurotransmitters, although the functional role of these co-transmitters remains incompletely understood. Within the brain histamine operates through three receptor subtypes that are located on pre- and post-synaptic membranes. Some histamine receptors exhibit constitutive activity, and hence exist in an activated state even in the absence of histamine. Newer medications used to reduce sleepiness in narcolepsy patients in fact enhance histamine signaling by blunting the constitutive activity of these histamine receptors. In this chapter, we provide an overview of the central histamine system with an emphasis on its role in behavioral state regulation and how drugs targeting histamine receptors are used clinically to treat a wide range of sleep-wake disorders.

The Role of Cetirizine in the Changing Landscape of IV Antihistamines: A Narrative Review

Since 1955, the only available H1 antihistamines for intravenous administration have been first-generation formulations and, of those, only intravenously administered (IV) diphenhydramine is still approved in the USA. Orally administered cetirizine hydrochloride, a second-generation H1 antihistamine, has been safely used over-the-counter for many years. In 2019, IV cetirizine was approved for the treatment of acute urticaria. In light of this approval, this narrative review discusses the changing landscape of IV antihistamines for the treatment of histamine-mediated conditions. Specifically, IV antihistamines will be discussed as a treatment option for acute urticaria and angioedema, as premedication to prevent infusion reactions related to anticancer agents and other biologics, and as an adjunct treatment for anaphylaxis and other allergic reactions. Before the development of IV cetirizine, randomized controlled trials of IV antihistamines for these indications were lacking. Three randomized controlled trials have been conducted with IV cetirizine versus IV diphenhydramine in the ambulatory care setting. A phase 3 trial of IV cetirizine 10 mg versus IV diphenhydramine 50 mg was conducted in 262 adults who presented to the urgent care/emergency department with acute urticaria requiring antihistamines. For the primary efficacy endpoint, defined as change from baseline in a 2-h patient-rated pruritus score, non-inferiority of IV cetirizine to IV diphenhydramine was demonstrated (score - 1.6 vs - 1.5, respectively; 95% CI - 0.1, 0.3). Compared with IV diphenhydramine, IV cetirizine demonstrated fewer adverse effects including less sedation, a significantly shorter length of stay in the treatment center, and fewer returns to the treatment center at 24 and 48 h. Similar findings were demonstrated in another phase 2 acute urticaria trial and in a phase 2 trial assessing IV cetirizine for pretreatment for infusion reactions in the oncology/immunology setting. IV cetirizine is associated with similar patient outcomes, fewer adverse effects, and increased treatment center efficiency than IV diphenhydramine.

An Update on Assessment, Therapeutic Management, and Patents on Insomnia

Insomnia is an ordinary situation related to noticeable disability in function and quality of life, mental and actual sickness, and mishappenings. It represents more than 5.5 million appointments to family doctors every year. Nonetheless, the ratio of insomniacs who are treated keeps on being low, demonstrating the requirement for proceeding with advancement and dispersal of effective treatments. Accordingly, it becomes significant to provide a compelling treatment for clinical practice. It indicates a need for the determination of various critical viewpoints for the evaluation of insomnia along with various accessible alternatives for treatment. These alternatives incorporate both nonpharmacological therapy, specifically cognitive behavioural therapy for insomnia, and a number of pharmacological treatments like orexin antagonists, "z-drugs," benzodiazepines, selective histamine H1 antagonists, nonselective antihistamines, melatonin receptor agonists, antipsychotics, antidepressants, and anticonvulsants. Besides in individuals whose insomnia is due to restless leg syndrome, depression/mood disorder, or/and circadian disturbance, there is insignificant proof favouring the effectiveness of different prescriptions for the treatment of insomnia though they are widely used. Other pharmacological agents producing sedation should be prescribed with care for insomnia therapy because of greater risk of next-day sleepiness along with known adverse effects and toxicities. This review is also aimed at providing an update on various patents on dosage forms containing drugs for insomnia therapy.

A network meta-analysis of the long- and short-term efficacy of sleep medicines in adults and older adults

BACKGROUND

This study focuses on seven commonly used hypnotics to comprehensively analyze the effects of long- and short-term use on sleep outcomes among adults and older adults.

METHODS

A network meta-analysis was performed. The insomnia medications were classified into seven categories: benzodiazepines, z-drugs, melatonin, H1-antagonists, orexin receptor antagonists (ORAs), antidepressants, and anticonvulsants. We compared their efficacy of total sleep time, sleep latency, sleep efficiency and wake after sleep onset in subgroups short-term, long-term, elderly, and adults.

RESULTS

A total of 111 RCTs involving 25,923 participants were included in this study.

CONCLUSIONS

ORAs can be widely used in adults and the elderly, and both short-term and long-term use are effective for primary insomnia. H1-antagonists are more effective in adults than in the elderly. Although benzodiazepines have a more obvious effect on sleep maintenance, it is best to reduce their use due to their side effects, especially for the elderly. As a food supplement, melatonin has little effect on adults, but it still has a certain effect on the elderly.

Changes in histaminergic system in neuropsychiatric disorders and the potential treatment consequences

In contrast to that of other monoamine neurotransmitters, the association of the histaminergic system with neuropsychiatric disorders is not well documented. In the last two decades, several clinical studies involved in the development of drugs targeting the histaminergic system have been reported. These include the H3R-antagonist/inverse agonist, pitolisant, used for the treatment of excessive sleepiness in narcolepsy, and the H1R antagonist, doxepin, used to alleviate symptoms of insomnia. The current review summarizes reports from animal models, including genetic and neuroimaging studies, as well as human brain samples and cerebrospinal fluid measurements from clinical trials, on the possible role of the histaminergic system in neuropsychiatric disorders. These studies will potentially pave the way for novel histamine-related therapeutic strategies.

Effectiveness of low-dose amitriptyline and mirtazapine for insomnia disorder: study protocol of a randomised, double-blind, placebo-controlled trial in general practice (the DREAMING study)

INTRODUCTION

For over more than a decade, low-dose amitriptyline and mirtazapine are prescribed off-label for insomnia. However, placebo-controlled evidence on these antidepressants for insomnia is still lacking. Therefore, the present trial aims to assess the effectiveness of low-dose amitriptyline (10-20 mg/day) and mirtazapine (7.5-15 mg/day) in patients with insomnia disorder with difficulty maintaining sleep or early-morning awakening problems in general practice.

METHODS AND ANALYSIS

The Drug REdiscovery: low-dose Amitriptyline and Mirtazapine for INsomnia disorder in General practice (DREAMING) study is a randomised, double-blind, placebo-controlled trial in about 50 general practices. Adults (18-85 years) with insomnia disorder (Diagnostic and Statistical Manual of Mental Disorders-5) who ask their general practitioner (GP) for sleep medication when non-pharmacological treatment is deemed not effective, are eligible.

EXCLUSION CRITERIA

isolated sleep initiation problem, contraindications for or drug-drug interactions with either amitriptyline or mirtazapine. Participants (n=156) will be randomly assigned to three parallel treatment groups of 16-week treatment with either amitriptyline (one or two tablets of 10 mg/day) or mirtazapine (one or two tablets of 7.5 mg/day) or placebo (one or two tablets) alongside usual GP care. All participants start and end with single dose, but dose can be doubled following GP consultation in week 3. Questionnaire assessments will be conducted at baseline, week 6, 12, 20 and 52. The primary study outcome is self-reported insomnia severity at 6 weeks, measured with the Insomnia Severity Index (ISI) in an intention to treat analysis. Secondary outcomes include subjective sleep quality quantified by sleep indices, daytime functioning and symptoms, safety and treatment evaluation and other sleep care consumption.

ETHICS AND DISSEMINATION

The Medical Ethics Committee of the VU Medical Centre Amsterdam approved this trial. The results of this trial will be published in peer-reviewed scientific journals and presented at relevant academic conferences and to key stakeholders.

TRIAL REGISTRATION NUMBER

NTR7449.

Review of Pharmacologic Sleep Agents for Critically Ill Patients

Sleep is a dynamic restorative process that is frequently disrupted in critically ill patients. Inadequate sleep can contribute to delirium and impaired healing. The etiology is multifactorial and practitioners often use a combination of nonpharmacologic and pharmacologic therapies to promote a healthy sleep cycle. There are many pharmacologic agents that may be used to promote sleep, and they display varying degrees of efficacy and safety. The selection of agent(s) should be based on patient- and disease-specific factors. All members of the treatment team can aid in assessing and optimizing sleep for critically ill patients.

No Time for Lullabies Tracing down Pharmacological Effects & Uses of H1-Antihistamines in Children Younger than 6 Years

Objectives. To provide a qualitative and a quantitative analysis of H1-antihistamines pharmacological uses pattern among children (<6 years old) and to evaluate the parental-related awareness. Methods. A cross-sectional study was carried out at 5 retail pharmacies in Jordan over 5 months (October/2019-February/2020). Parents who requested any of H1-antihistmine agent for a child (<6 years) were invited to participate. Results. A total of 516 children, most of them were toddlers (1-3) years, received at least 1 H1-antihistamine. More than half of the cases received H1-antihistamine as self-medication (56.3%). Sedating antihistamine agents were the most frequently used among children (<6 years old) (77.9%) among which Chlorpheniramine maleate was the most commonly used agent (62.9%). About half of the children (47.0%) received H1-antihistamine to induce sleep. Whereas, 21.7% and 12.9% received them to manage flu, and allergic rhinitis (AR), respectively. Around 66.6% of the cases were classified as off-label use. Most of the parents (80.5%) were aware of the sedative adverse effects of H1-antihistamines, whereas a fewer number (31.9%) were aware of their cognitive effects. Finally, more than two thirds of parents (79.7%) were unfamiliar with off-label drug use in children. Conclusion. Despite the availability of less-sedating H1-antihistamines with a wide safety and efficacy record, the use of sedating H1-antihistamines remains popular in children.

A structure-kinetic relationship study using matched molecular pair analysis

The lifetime of a binary drug–target complex is increasingly acknowledged as an important parameter for drug efficacy and safety. With a better understanding of binding kinetics and better knowledge about kinetic parameter optimization, intentionally induced prolongation of the drug–target residence time through structural changes of the ligand could become feasible. In this study we assembled datasets from 21 publications and the K4DD (Kinetic for Drug Discovery) database to conduct large scale data analysis. This resulted in 3812 small molecules annotated to 78 different targets from five protein classes (GPCRs: 273, kinases: 3238, other enzymes: 240, HSPs: 160, ion channels: 45). Performing matched molecular pair (MMP) analysis to further investigate the structure–kinetic relationship (SKR) in this data collection allowed us to identify a fundamental contribution of a ligand's polarity to its association rate, and in selected cases, also to its dissociation rate. However, we furthermore observed that the destabilization of the transition state introduced by increased polarity is often accompanied by simultaneous destabilization of the ground state resulting in an unaffected or even worsened residence time. Supported by a set of case studies, we provide concepts on how to alter ligands in ways to trigger on-rates, off-rates, or both.

A large-scale study employing matched molecular pair (MMP) analysis to uncover the contribution of a compound's polarity to its association and dissociation rates.

Similar, or dissimilar, that is the question. How different are methods for comparison of compounds similarity?

Comparison of compounds similarity is one of the main strategies of virtual screening protocols. Both similarity and dissimilarity concepts are of great importance during the search for new active compounds. Similarity is important due to the assumption that underlies the process of searching for new drug candidates: structurally similar compounds should induce similar biological response. On the other hand, we are also interested in dissimilarity, as we usually aim to find structurally novel ligands. In the study, we compared several approaches of evaluating compound similarity. Various representations and metrics were applied and we indicated the rate of variation of the results that can occur when shifting from one strategy to another. We compared both general similarity of datasets using different approaches, as well as examined the changes in the set of nearest neighbors when changing one compound representation into another, and the influence of representation/metric settings on the clustering outcome. We hope that the study will be of great help during the preparation of virtual screening experiments, stressing the need for careful selection of the way, the compound similarity is assessed. The differences in the results that can be obtained via the application of particular strategy can significantly influence the outcome of comparison studies; therefore, its settings should be carefully selected beforerunning the comparison.

Voltage-dependent modulation of TRPA1 currents by diphenhydramine

Diphenhydramine (DPH) has been broadly used to treat allergy. When used as a topical medicine, DPH temporarily relieves itching and pain. Although transient receptor potential type A1 (TRPA1) channel is known to play roles in both acute and chronic itch and pain, whether DPH affects the activities of TRPA1 remains unclear. Using whole-cell patch clamp recordings, we demonstrated that DPH modulates the voltage-dependence of TRPA1. When co-applied with a TRPA1 agonist, DPH significantly enhanced the inward currents while suppressing the outward currents of TRPA1, converting the channel from outwardly rectifying to inwardly rectifying. This effect of DPH occurred no matter TRPA1 was activated by an electrophilic or non-electrophilic agonist and for both mouse and human TRPA1. The modulation of TRPA1 by DPH was maintained in the L906C mutant, which by itself also causes inward rectification of TRPA1, indicating that additional acting sites are present for the modulation of TRPA1 currents by DPH. Our recordings also revealed that DPH partially blocked capsaicin evoked TRPV1 currents. These data suggest that DPH may exert its therapeutic effects on itch and pain, through modulation of TRPA1 in a voltage-dependent fashion.

The Use of Sleep Medication in Youth Residential Care

Objectives: To investigate the use of sleep medication and concomitant psychotropic medication in children and adolescents placed under residential care (RC). Methods: Participants were youth 0-20 years of age placed in RC institutions at least once during 2016. Data on filled prescriptions were taken from the Norwegian Prescription Database to compare the use of sleep medication in RC with the general child population (GenPop) and how it covaried with gender, age, reasons for RC placement, and concomitant use of other psychotropic medications (antidepressants, anxiolytics, antipsychotics, and psychostimulants). Results: A total of 2171 youths were identified in RC at mean age 14 years (82% ≥ 13 years). Seventeen percent (371/2171) used sleep medications (melatonin 11%, alimemazine 7%, and benzodiazepines/z-hypnotics 2%) significantly more than the 2.3% who used in GenPop. The girl/boy ratio for medication use in RC was 1.8 (95% confidence interval [CI] = 1.5-2.2), not significantly different from the corresponding ratio in GenPop (1.4; 95% CI = 1.3-1.5). The use of sleep medication increased with age. When comparing reasons for placement in RC, medication use was particularly low among unaccompanied minor asylum seekers (2%). About half of the youths used concomitant psychotropic medication, with clear gender differences; girls used about twice as much antidepressants, anxiolytics, and antipsychotics, whereas boys used 1.3 times more psychostimulants. Conclusion: Youths in RC used more sleep medication and concomitant psychotropic medication than the GenPop, most likely reflecting the increased psychosocial strain and mental disorders reported in this population. Further studies of prevalence, assessment, and treatment of sleep problems in RC populations are warranted.

Hypnotics with novel modes of action

Insomnia and, more generally, lack of sleep are on the rise. Traditionally treated by classical hypnotics, such as benzodiazepines and Z drugs, which both act on the GABAA receptor, and other modalities, including nondrug therapies, such as cognitive behavioural therapy, there is a range of new hypnotics which are being developed or have recently received market approval. Suvorexant and the like target the orexin/hypocretin system: they should have less side effects in terms of drug-drug interactions with e.g. alcohol, less memory impairment and dependence potential compared to classical hypnotics.

The therapeutic versatility of antihistamines: A comprehensive review

Antihistamines are common and readily available medications for primary care patients and those seeking over-the-counter treatments. This article provides an overview of available antihistamines, their mechanisms of action, safety concerns in specific populations, and their therapeutic uses in several common conditions.

Sleep therapeutics and neuropsychiatric illness

Alterations in sleep are extremely common in patients with neuropsychiatric illness. In addition, sleep disorders such as insomnia, obstructive sleep apnea, rapid eye movement sleep behavior disorder, and circadian rhythm disorders commonly occur at a rate greater than the general population in neuropsychiatric conditions. Historically, sleep problems have been viewed as symptoms of associated neuropsychiatric disorders. However, there is increasing evidence suggesting a complex inter-relationship with possible bidirectional causality. The inter-relatedness of these conditions represents an opportunity for understanding mechanisms and improving clinical treatment. To the extent that sleep problems affect neuropsychiatric conditions, it may be possible to address sleep problems and have a positive impact on the course of neuropsychiatric illnesses. Further, some treatments for sleep disorders have direct effects on neuropsychiatric illnesses that may be unrelated to their effects on sleep disorders. Similarly, neuropsychiatric conditions and their treatments can affect sleep and sleep disorders. This article reviews available evidence on the effects of therapies for sleep disorders on neuropsychiatric conditions and also secondarily considers the impacts of therapies for neuropsychiatric conditions on sleep. Primary goals of this review are to identify gaps in current research, to determine the extent to which the cross-therapeutic effects of these treatments help to elucidate therapeutic or pathological mechanisms, and to assist clinicians in optimizing therapeutic choice in patients with sleep disorders and neuropsychiatric conditions.

The assessment and management of insomnia: an update

Insomnia poses significant challenges to public health. It is a common condition associated with marked impairment in function and quality of life, psychiatric and physical morbidity, and accidents. As such, it is important that effective treatment is provided in clinical practice. To this end, this paper reviews critical aspects of the assessment of insomnia and the available treatment options. These options include both non-medication treatments, most notably cognitive behavioral therapy for insomnia, and a variety of pharmacologic therapies such as benzodiazepines, "z-drugs", melatonin receptor agonists, selective histamine H1 antagonists, orexin antagonists, antidepressants, antipsychotics, anticonvulsants, and non-selective antihistamines. A review of the available research indicates that rigorous double-blind, randomized, controlled trials are lacking for some of the most commonly administered insomnia therapies. However, there are an array of interventions which have been demonstrated to have therapeutic effects in insomnia in trials with the above features, and whose risk/benefit profiles have been well characterized. These interventions can form the basis for systematic, evidence-based treatment of insomnia in clinical practice. We review this evidence base and highlight areas where more studies are needed, with the aim of providing a resource for improving the clinical management of the many patients with insomnia.

Reassessing the Role of Histaminergic Tuberomammillary Neurons in Arousal Control

The histaminergic neurons of the tuberomammillary nucleus (TMN^HDC) of the posterior hypothalamus have long been implicated in promoting arousal. More recently, a role for GABAergic signaling by the TMN^HDC neurons in arousal control has been proposed. Here, we investigated the effects of selective chronic disruption of GABA synthesis (via genetic deletion of the GABA synthesis enzyme, glutamic acid decarboxylase 67) or GABAergic transmission (via genetic deletion of the vesicular GABA transporter (VGAT)) in the TMN^HDC neurons on sleep-wake in male mice. We also examined the effects of acute chemogenetic activation and optogenetic inhibition of TMN^HDC neurons upon arousal in male mice. Unexpectedly, we found that neither disruption of GABA synthesis nor GABAergic transmission altered hourly sleep-wake quantities, perhaps because very few TMN^HDC neurons coexpressed VGAT. Acute chemogenetic activation of TMN^HDC neurons did not increase arousal levels above baseline but did enhance vigilance when the mice were exposed to a behavioral cage change challenge. Similarly, acute optogenetic inhibition had little effect upon baseline levels of arousal. In conclusion, we could not identify a role for GABA release by TMN^HDC neurons in arousal control. Further, if TMN^HDC neurons do release GABA, the mechanism by which they do so remains unclear. Our findings support the view that TMN^HDC neurons may be important for enhancing arousal under certain conditions, such as exposure to a novel environment, but play only a minor role in behavioral and EEG arousal under baseline conditions.SIGNIFICANCE STATEMENT The histaminergic neurons of the tuberomammillary nucleus of the hypothalamus (TMN^HDC) have long been thought to promote arousal. Additionally, TMN^HDC neurons may counter-regulate the wake-promoting effects of histamine through co-release of the inhibitory neurotransmitter, GABA. Here, we show that impairing GABA signaling from TMN^HDC neurons does not impact sleep-wake amounts and that few TMN^HDC neurons contain the vesicular GABA transporter, which is presumably required to release GABA. We further show that acute activation or inhibition of TMN^HDC neurons has limited effects upon baseline arousal levels and that activation enhances vigilance during a behavioral challenge. Counter to general belief, our findings support the view that TMN^HDC neurons are neither necessary nor sufficient for the initiation and maintenance of arousal under baseline conditions.

Novel pharmacological targets in drug development for the treatment of anxiety and anxiety-related disorders

Current medication for anxiety disorders is suboptimal in terms of efficiency and tolerability, highlighting the need for improved drug treatments. In this review an overview of drugs being studied in different phases of clinical trials for their potential in the treatment of fear-, anxiety- and trauma-related disorders is presented. One strategy followed in drug development is refining and improving compounds interacting with existing anxiolytic drug targets, such as serotonergic and prototypical GABAergic benzodiazepines. A more innovative approach involves the search for compounds with novel mechanisms of anxiolytic action using the growing knowledge base concerning the relevant neurocircuitries and neurobiological mechanisms underlying pathological fear and anxiety. The target systems evaluated in clinical trials include glutamate, endocannabinoid and neuropeptide systems, as well as ion channels and targets derived from phytochemicals. Examples of promising novel candidates currently in clinical development for generalised anxiety disorder, social anxiety disorder, panic disorder, obsessive compulsive disorder or post-traumatic stress disorder include ketamine, riluzole, xenon with one common pharmacological action of modulation of glutamatergic neurotransmission, as well as the neurosteroid aloradine. Finally, compounds such as D-cycloserine, MDMA, L-DOPA and cannabinoids have shown efficacy in enhancing fear-extinction learning in humans. They are thus investigated in clinical trials as an augmentative strategy for speeding up and enhancing the long-term effectiveness of exposure-based psychotherapy, which could render chronic anxiolytic drug treatment dispensable for many patients. These efforts are indicative of a rekindled interest and renewed optimism in the anxiety drug discovery field, after decades of relative stagnation.

In Silico Study of Anti-Insomnia Mechanism for Suanzaoren Prescription

Insomnia is a common and widespread sleeping disorder caused by various risk factors. Though beneficial, conventional treatments of insomnia have significant limitations. As an alternative treatment, Chinese herbal formula Suanzaoren prescription (SZRP), composed of Suanzaoren [seeds of Ziziphus jujuba var. spinosa (Bunge) Hu ex H.F.Chow] and four additional herbs, has been reported with significant anti-insomnia effects. Yet the anti-insomnia mechanism of the herb formulae remains unknown. In this study, we attempted to extrapolate the holistic anti-insomnia mechanism of SZRP through herbal targeting and network pharmacology. The results indicated that the ingredients of Suanzaoren can target multi-neurotransmitter receptors at synapse interface, which was reported to be associated with sedative and hypnotic effects, while the four additional herbs can hit multiple pathways downstream of membrane neurotransmitters. Furthermore, the four additional herbs showed highly cooperative targeting patterns in the paralleled and cross-talked pathways related to inflammatory regulation and endocrine system, which may contribute to the additional relief of insomnia caused by inflammation, anxiety, or endocrine disorder. The interesting complementary mechanism we found among the herbal groups of SZRP may provide an example to study Chinese herbal formula and offers clues to future design of anti-insomnia strategy.

British Association for Psychopharmacology consensus statement on evidence-based treatment of insomnia, parasomnias and circadian rhythm disorders: An update

This British Association for Psychopharmacology guideline replaces the original version published in 2010, and contains updated information and recommendations. A consensus meeting was held in London in October 2017 attended by recognised experts and advocates in the field. They were asked to provide a review of the literature and identification of the standard of evidence in their area, with an emphasis on meta-analyses, systematic reviews and randomised controlled trials where available, plus updates on current clinical practice. Each presentation was followed by discussion, aiming to reach consensus where the evidence and/or clinical experience was considered adequate, or otherwise to flag the area as a direction for future research. A draft of the proceedings was circulated to all speakers for comments, which were incorporated into the final statement.

Sleep Pharmacogenetics: The Promise of Precision Medicine

Pharmacogenetics is the branch of personalized medicine concerned with the variability in drug response occurring because of heredity. Advances in genetics research, and decreasing costs of gene sequencing, are promoting tremendous growth in pharmacogenetics in all areas of medicine, including sleep medicine. This article reviews the body of research indicating that there are genetic variations that affect the therapeutic actions and adverse effects of agents used for the treatment of sleep disorders to show the potential of pharmacogenetics to improve the clinical practice of sleep medicine.

Clinical and Experimental Human Sleep-Wake Pharmacogenetics

Sleep and wakefulness are highly complex processes that are elegantly orchestrated by fine-tuned neurochemical changes among neuronal and non-neuronal ensembles, nuclei, and networks of the brain. Important neurotransmitters and neuromodulators regulating the circadian and homeostatic facets of sleep-wake physiology include melatonin, γ-aminobutyric acid, hypocretin, histamine, norepinephrine, serotonin, dopamine, and adenosine. Dysregulation of these neurochemical systems may cause sleep-wake disorders, which are commonly classified into insomnia disorder, parasomnias, circadian rhythm sleep-wake disorders, central disorders of hypersomnolence, sleep-related movement disorders, and sleep-related breathing disorders. Sleep-wake disorders can have far-reaching consequences on physical, mental, and social well-being and health and, thus, need be treated with effective and rational therapies. Apart from behavioral (e.g., cognitive behavioral therapy for insomnia), physiological (e.g., chronotherapy with bright light), and mechanical (e.g., continuous positive airway pressure treatment of obstructive sleep apnea) interventions, pharmacological treatments often are the first-line clinical option to improve disturbed sleep and wake states. Nevertheless, not all patients respond to pharmacotherapy in uniform and beneficial fashion, partly due to genetic differences. The improved understanding of the neurochemical mechanisms regulating sleep and wakefulness and the mode of action of sleep-wake therapeutics has provided a conceptual framework, to search for functional genetic variants modifying individual drug response phenotypes. This article will summarize the currently known genetic polymorphisms that modulate drug sensitivity and exposure, to partly determine individual responses to sleep-wake pharmacotherapy. In addition, a pharmacogenetic strategy will be outlined how based upon classical and opto-/chemogenetic strategies in animals, as well as human genetic associations, circuit mechanisms regulating sleep-wake functions in humans can be identified. As such, experimental human sleep-wake pharmacogenetics forms a bridge spanning basic research and clinical medicine and constitutes an essential step for the search and development of novel sleep-wake targets and therapeutics.

[Pharmacotherapy of Sleep-Wake Disorders]

Pharmacotherapy of Sleep-Wake Disorders Abstract. Sleep is a complex behavior, coordinated by many different brain regions and neurotransmitters. These neurochemical systems can be pharmacologically influenced to modulate wakefulness and sleep. Excessive daytime sleepiness (EDS) is often treated with dopaminergic drugs, which in mild cases range from caffeine via (ar)modafinil to amphetamine derivatives. Tricyclic antidepressants and melatonin-based drugs are also used to promote alertness, but to a lesser extent. The drugs used to promote sleep include GABA-ergic drugs such as benzodiazepines and Z-hypnotics as well as histamine H1 receptor antagonists. Exogenous melatonin or a pharmacological combination of melatonin receptor agonists and 5-HT2C receptor antagonists are also used in mild cases. Selective and dual orexin (hypocretin) receptor antagonists (DORA) as well as drugs binding to specific 5-HT receptors are currently being investigated as future sleep-promoting drugs. However, pharmacological treatment is not always the primary treatment option, insomnia is treated first-line with cognitive behavioral therapy, and continuous positive airway pressure is used to treat sleep apnea.

Identification of Primary Natural Killer Cell Modulators by Chemical Library Screening with a Luciferase-Based Functional Assay

Natural killer (NK) cells are essential players of the innate immune response that secrete cytolytic factors and cytokines such as IFN-γ when contacting virus-infected or tumor cells. They represent prime targets in immunotherapy as defects in NK cell functions are hallmarks of many pathological conditions, such as cancer and chronic infections. The functional screening of chemical libraries or biologics would greatly help identify new modulators of NK cell activity, but commonly used methods such as flow cytometry are not easily scalable to high-throughput settings. Here we describe an efficient assay to measure the natural cytotoxicity of primary NK cells where the bioluminescent enzyme NanoLuc is constitutively expressed in the cytoplasm of target cells and is released in co-culture supernatants when lysis occurs. We fully characterized this assay using either purified NK cells or total peripheral blood mononuclear cells (PBMCs), including some patient samples, as effector cells. A pilot screen was also performed on a library of 782 metabolites, xenobiotics, and common drugs, which identified dextrometorphan and diphenhydramine as novel NK cell inhibitors. Finally, this assay was further improved by developing a dual-reporter cell line to simultaneously measure NK cell cytotoxicity and IFN-γ secretion in a single well, extending the potential of this system.

Pharmacotherapy of Insomnia

Insomnia remains a common clinical concern that is associated with negative daytime consequences for patients and represents a significant public health problem for our society. Although a variety of therapies may be employed to treat insomnia, the use of medications has been a dominant approach. Regulatory agencies have now classified insomnia medications into 4 distinct pharmacodynamics classes. Medications with indications approved for insomnia treatment include benzodiazepine receptor agonists, a melatonin receptor agonist, a selective histamine receptor antagonist, and a dual orexin/hypocretin receptor antagonist. Both pharmacodynamic and pharmacokinetic advances with hypnotic medications in recent years have expanded the pharmacopoeia to allow personalized treatment approaches for different patient populations and individual sleep disturbance patterns.

Effects of Amitriptyline and Escitalopram on Sleep and Mood in Patients With Functional Dyspepsia

BACKGROUND & AIMS

Tricyclic antidepressants are effective in reducing symptoms of functional dyspepsia (FD). We performed a post hoc analysis of data from a previous randomized clinical trial to determine whether the benefits of an antidepressant on gastrointestinal symptoms in patients with FD were mediated by improving sleep or reducing anxiety. We explored the relationships between psychological measures, quality of sleep, and relief of symptoms.

METHODS

We analyzed data from a multicenter, double-blind trial that evaluated the efficacy of antidepressants on symptoms of FD, from October 2006 through October 2012. Patients (n = 292) were randomly assigned to groups given 50 mg amitriptyline, 10 mg escitalopram, or placebo for 12 weeks. During the study, participants completed the following validated psychological questionnaires: Symptom Check List 90, Symptom Somatic Checklist, Hospital Anxiety Depression Scale, Profile of Mood States, State Trait Anxiety Inventory, and Pittsburgh Sleep Quality Index at baseline and 12 weeks following treatment.

RESULTS

Baseline scores for the psychological and sleep measures were similar among groups; after 12 weeks there were no significant differences in scores among groups. Baseline mean global Pittsburgh Sleep Quality Index scores indicated poor sleep quality in all groups at baseline and after 12 weeks. Overall, antidepressants affected sleep duration scores: patients given amitriptyline had lower (better) scores than patients given placebo or escitalopram (P = .019). In all groups, responders had decreased anxiety and improvements in some sleep components.

CONCLUSIONS

In a post hoc analysis of data from a clinical trial that evaluated the effects of antidepressants in patients with FD, amitriptyline was found to reduce symptoms of FD, but its mechanism is unlikely to involve reductions in psychological distress. The drug may modestly improve sleep. Clinicaltrials.gov no: NCT00248651.

Orexin OX2 Receptor Antagonists as Sleep Aids

The discovery of the orexin system represents the single major progress in the sleep field of the last three to four decades. The two orexin peptides and their two receptors play a major role in arousal and sleep/wake cycles. Defects in the orexin system lead to narcolepsy with cataplexy in humans and dogs and can be experimentally reproduced in rodents. At least six orexin receptor antagonists have reached Phase II or Phase III clinical trials in insomnia, five of which are dual orexin receptor antagonists (DORAs) that target both OX1 and OX2 receptors (OX2Rs). All clinically tested DORAs induce and maintain sleep: suvorexant, recently registered in the USA and Japan for insomnia, represents the first hypnotic principle that acts in a completely different manner from the current standard medications. It is clear, however, that in the clinic, all DORAs promote sleep primarily by increasing rapid eye movement (REM) and are almost devoid of effects on slow-wave (SWS) sleep. At present, there is no consensus on whether the sole promotion of REM sleep has a negative impact in patients suffering from insomnia. However, sleep onset REM (SOREM), which has been documented with DORAs, is clearly an undesirable effect, especially for narcoleptic patients and also in fragile populations (e.g. elderly patients) where REM-associated loss of muscle tone may promote an elevated risk of falls. Debate thus remains as to the ideal orexin agent to achieve a balanced increase in REM and non-rapid eye movement (NREM) sleep. Here, we review the evidence that an OX2R antagonist should be at least equivalent, or perhaps superior, to a DORA for the treatment of insomnia. An OX2R antagonist may produce more balanced sleep than a DORA. Rodent sleep experiments show that the OX2R is the primary target of orexin receptor antagonists in sleep modulation. Furthermore, an OX2R antagonist should, in theory, have a lower narcoleptic/cataplexic potential. In the clinic, the situation remains equivocal, since OX2R antagonists are in early stages: MK-1064 has completed Phase I, and MIN202 is currently in clinical Phase II/III trials. However, data from insomnia patients have not yet been released. Promotional material suggests that balanced sleep is indeed induced by MIN-202, whereas in volunteers MK-1064 has been reported to act similarly to DORAs.

Treatment of Insomnia With Traditional Chinese Herbal Medicine

Insomnia is a condition with sleep problems and many people suffered from it. Chronic insomnia can last for long time and it will severely affect people's health and the quality of life. In conventional medicine, the most commonly used the medicine is benzodiazepine. It is effective but also has significant side effects. Patients try to use some kinds of alternative medicines. Chinese medicinal herbs and formulas have been used in the treatment of insomnia for more than 2000 years in China. In recent decades, Chinese herbal medicine has been widely used in the Western countries. Many clinical studies including randomized controlled clinical trials and research on pharmacological action mechanisms of the herbs for treatment of insomnia have been conducted. It is very important and very helpful to review the published research papers to gather the available information for a critical analysis. This chapter evaluated the data from both of clinical studies and pharmacological researches on the therapeutic formulas and on some key herbs used in the treatment of insomnia. Clinical studies showed a very wide spectrum of herbs that were used in clinical treatment of insomnia. This was due to different syndrome patterns happened with insomnia. This brought complexity and difficulties to identify which are the essential key herbs or formulas. It was found Suanzaoren decoction (Ziziphus spinose decoction ) is the most frequently used formula for the treatment of insomnia. Based on the clinical data, several herbs were identified as most frequently used sedative and hypnotic herbs in Chinese herbal medicine including Suanzaoren (Ziziphus spinose ), Fuling (Poria cocos ), and Gancao (Glycyrrhiza uralensis ). The underlying pharmacological action mechanisms discovered in the studies on some key herbs used in the treatment of insomnia were evaluated. The major pharmacological action mechanisms shared by most of the sedative herbs are to act through the neurotransmitter gamma-aminobutyric acid (GABA) or via stimulation of GABAA_A receptor. Some herbs exert sedative activities via inhibition of 5-hydroxytryptamine 1A receptor. Another mechanism shown by some herbs is to upregulate the expression of orexin-A, leptin, orexin receptor-1, and leptin receptor in the brain, reducing insomnia-induced negative consequences, and thus indirectly help improvement of insomnia.

Changes in Histidine Decarboxylase, Histamine N-Methyltransferase and Histamine Receptors in Neuropsychiatric Disorders

Compared to other monoamine neurotransmitters, information on the association between the histaminergic system and neuropsychiatric disorders is scarce, resulting in a lack of histamine-related treatment for these disorders. The current chapter tries to combine information obtained from genetic studies, neuroimaging, post-mortem human brain studies and cerebrospinal fluid measurements with data from recent clinical trials on histamine receptor agonists and antagonists, with a view to determining the possible role of the histaminergic system in neuropsychiatric disorders and to pave the way for novel histamine-related therapeutic strategies.

Disrupted Sleep in Narcolepsy: Exploring the Integrity of Galanin Neurons in the Ventrolateral Preoptic Area

STUDY OBJECTIVES

To examine the integrity of sleep-promoting neurons of the ventrolateral preoptic nucleus (VLPO) in postmortem brains of narcolepsy type 1 patients.

METHODS

Postmortem examination of five narcolepsy and eight control brains.

RESULTS

VLPO galanin neuron count did not differ between narcolepsy patients (11,151 ± 3,656) and controls (13,526 ± 9,544).

CONCLUSIONS

A normal number of galanin-immunoreactive VLPO neurons in narcolepsy type 1 brains at autopsy suggests that VLPO cell loss is an unlikely explanation for the sleep fragmentation that often accompanies the disease.

Pharmacotherapy Treatment Options for Insomnia: A Primer for Clinicians

Insomnia is a prevalent disorder with deleterious effects such as decreased quality of life, and a predisposition to a number of psychiatric disorders. Fortunately, numerous approved hypnotic treatments are available. This report reviews the state of the art of pharmacotherapy with a reference to cognitive behavioral therapy for insomnia (CBT-I) as well. It provides the clinician with a guide to all the Food and Drug Administration (FDA) approved hypnotics (benzodiazepines, nonbenzodiazepines, ramelteon, low dose sinequan, and suvorexant) including potential side effects. Frequently, chronic insomnia lasts longer than 2 years. Cognizant of this and as a result of longer-term studies, the FDA has approved all hypnotics since 2005 without restricting the duration of use. Our manuscript also reviews off-label hypnotics (sedating antidepressants, atypical antipsychotics, anticonvulsants and antihistamines) which in reality, are more often prescribed than approved hypnotics. The choice of which hypnotic to choose is discussed partially being based on which segment of sleep is disturbed and whether co-morbid illnesses exist. Lastly, we discuss recent label changes required by the FDA inserting a warning about “sleep-related complex behaviors”, e.g., sleep-driving for all hypnotics. In addition, we discuss FDA mandated dose reductions for most zolpidem preparations in women due to high zolpidem levels in the morning hours potentially causing daytime carry-over effects.

New Developments in Insomnia Medications of Relevance to Mental Health Disorders

Many insomnia medications with high specificity have become available recently. They provide a window into the clinical effects of modulating specific brain systems and establish a new guiding principal for conceptualizing insomnia medications: "mechanism matters." A new paradigm for insomnia therapy in which specific drugs are selected to target the specific type of sleep difficulty for each patient includes administering specific treatments for patients with insomnia comorbid with particular psychiatric disorders. This article reviews insomnia medications and discusses the implications for optimizing the treatment of insomnia occurring comorbid with psychiatric conditions.

Insomnia disorder

Insomnia disorder affects a large proportion of the population on a situational, recurrent or chronic basis and is among the most common complaints in medical practice. The disorder is predominantly characterized by dissatisfaction with sleep duration or quality and difficulties initiating or maintaining sleep, along with substantial distress and impairments of daytime functioning. It can present as the chief complaint or, more often, co-occurs with other medical or psychiatric disorders, such as pain and depression. Persistent insomnia has been linked with adverse long-term health outcomes, including diminished quality of life and physical and psychological morbidity. Despite its high prevalence and burden, the aetiology and pathophysiology of insomnia is poorly understood. In the past decade, important changes in classification and diagnostic paradigms have instigated a move from a purely symptom-based conceptualization to the recognition of insomnia as a disorder in its own right. These changes have been paralleled by key advances in therapy, with generic pharmacological and psychological interventions being increasingly replaced by approaches that have sleep-specific and insomnia-specific therapeutic targets. Psychological and pharmacological therapies effectively reduce the time it takes to fall asleep and the time spent awake after sleep onset, and produce a modest increase in total sleep time; these are outcomes that correlate with improvements in daytime functioning. Despite this progress, several challenges remain, including the need to improve our knowledge of the mechanisms that underlie insomnia and to develop more cost-effective, efficient and accessible therapies.

Interactions of the histamine and hypocretin systems in CNS disorders

Histamine and hypocretin neurons are localized to the hypothalamus, a brain area critical to autonomic function and sleep. Narcolepsy type 1, also known as narcolepsy with cataplexy, is a neurological disorder characterized by excessive daytime sleepiness, impaired night-time sleep, cataplexy, sleep paralysis and short latency to rapid eye movement (REM) sleep after sleep onset. In narcolepsy, 90% of hypocretin neurons are lost; in addition, two groups reported in 2014 that the number of histamine neurons is increased by 64% or more in human patients with narcolepsy, suggesting involvement of histamine in the aetiology of this disorder. Here, we review the role of the histamine and hypocretin systems in sleep-wake modulation. Furthermore, we summarize the neuropathological changes to these two systems in narcolepsy and discuss the possibility that narcolepsy-associated histamine abnormalities could mediate or result from the same processes that cause the hypocretin cell loss. We also review the changes in the hypocretin and histamine systems, and the associated sleep disruptions, in Parkinson disease, Alzheimer disease, Huntington disease and Tourette syndrome. Finally, we discuss novel therapeutic approaches for manipulation of the histamine system.