Role of melatonin in the induction and maintenance of sleep

Comparative Pharmacokinetics of Sustained-Release versus Immediate-Release Melatonin Capsules in Fasting Healthy Adults: A Randomized, Open-Label, Cross-Over Study

Background: Exogenous melatonin, a nutraceutical for maintaining a healthy sleep-wake cycle and managing sleep disorders, requires large, repeated doses due to its low bioavailability and short half-life. This necessitates the development of a sustained-release formulation with a longer half-life and sustained plasma concentration. Therefore, exogenous novel 5 mg sustained-release melatonin capsules (Melatonin-SR, test product) were formulated. Methods: This open-label cross-over study compared the pharmacokinetics (maximum concentration [Cmax], time to reach Cmax [Tmax], area under the curve [AUC], and elimination half-life [t1/2]) and the safety of Melatonin-SR with 5 mg immediate-release melatonin capsules (Melatonin-IR, reference product) after single-dose oral administration in healthy fasting adults. Results: Sixteen participants (aged 18-45 years) were randomized (1:1) to receive either Melatonin-SR or Melatonin-IR in two periods with a 7-day washout period. Melatonin-SR reported a lower Cmax (11,446.87 pg/mL) compared to Melatonin-IR (22,786.30 pg/mL). The mean Tmax of Melatonin-SR and Melatonin-IR was 1.26 h and 0.87 h, respectively. The mean t1/2 of Melatonin-SR (5.10 h) was prolonged by five-fold compared to Melatonin-IR (1.01 h). One adverse event (vomiting) was reported following the administration of the Melatonin-IR. Conclusions: Melatonin-SR resulted in higher and sustained plasma melatonin concentrations for an extended period and was well-tolerated. Hence, Melatonin-SR may be a promising nutraceutical for maintaining healthy sleep.

Essential Oils and Melatonin as Functional Ingredients in Dogs

Simple Summary

Phytogenics are plant-based compounds with beneficial actions in feed technology and/or animal health. These so-called plant secondary metabolites are very diverse and with wide possible applications in humans and animals. Among them, essential oils (EOs) are the most used in feed for livestock and pets. Lately, melatonin has acquired new and interesting applications in dogs. Recent studies using EOs and/or melatonin in dog feeding and their involvement in health aspects are presented.

Abstract

The use of nutraceuticals or functional ingredients is increasingly widespread in human food; their use is also widespread in animal feed. These natural compounds generally come from plant materials and comprise a wide range of substances of a very diverse chemical nature. In animals, these compounds, so-called phytogenics, are used to obtain improvements in feed production/stability and also as functional components with repercussions on animal health. Along with polyphenols, isoprenoid compounds represent a family of substances with wide applications in therapy and pet nutrition. Essential oils (EOs) are a group of complex substances with fat-soluble nature that are widely used. Melatonin is an indolic amine present in all living with amphiphilic nature. In this work, we present a review of the most relevant phytogenics (polyphenol, isoprenoid, and alkaloid compounds), their characteristics, and possible uses as nutraceuticals in dogs, with special emphasis on EOs and their regulatory aspects, applied in foods and topically. Additionally, a presentation of the importance of the use of melatonin in dogs is developed, giving physiological and practical aspects about its use in dog feeding and also in topical application, with examples and future projections. This review points to the combination of EOs and melatonin in food supplements and in the topical application as an innovative product and shows excellent perspectives aimed at addressing dysfunctions in pets, such as the treatment of stress and anxiety, sleep disorders, alopecia, and hair growth problems, among others.

Plasma 5-HIAA activity indicative of serotonergic disturbances in cognitively impaired, elderly patients experiencing postoperative delirium

OBJECTIVES

Delirium frequently arises in older demented and non-demented patients in postoperative, clinical settings. To date, the underlying pathophysiological mechanisms remain poorly understood. Monoamine neurotransmitter alterations have been linked to delirium and cognitive impairment. Our aim was to investigate if this holds true in cognitively normal and impaired patients experiencing delirium following hip surgery.

METHODS

Monoamines and metabolites were measured in plasma samples of 181 individuals by means of reversed-phase ultra-high-performance liquid chromatography with electrochemical detection. Delirium and delirium severity were scored with the Confusion Assessment Method and Delirium Rating Scale-Revised-1998. Cognitive function was assessed using the Informant Questionnaire on Cognitive Decline and the Mini-Mental State Examination, multimorbidity with the Charlson Comorbidity Index.

RESULTS

Plasma 5-hydroxyindoleacetic acid (5-HIAA), the major metabolite of serotonin (5-HT), was significantly higher in delirious and non-delirious cognitively impaired subjects as compared to control individuals without delirium and cognitive impairment (p < 0.001 and p = 0.007), which remained highly significant after excluding patients taking psychotropic medication (p < 0.0001 and p = 0.003). No significant differences were found for cognitively normal delirious patients, although serotonergic levels were numerically higher compared to control counterparts.

CONCLUSIONS

Our findings indicate a general serotonergic disturbance in delirious and non-delirious postoperative patients suffering from cognitive impairment. We observed a similar, but less pronounced difference in delirious patients, which suggests serotonergic disturbances may be further aggravated by the co-occurrence of delirium and cognitive impairment.

The synergic relationship between social anxiety, depressive symptoms, poor sleep quality and body fatness in adolescents

BACKGROUND

The aim of the current study was to evaluate the cross-sectional synergic relationship among social anxiety, poor sleep quality, depressive symptoms and body fatness.

METHODS

A cross-sectional study was performed with 1,242 adolescents from a north-eastern district in Brazil. It was used the Social Anxiety Scale for Adolescents for symptoms of social anxiety, the Pittsburgh Sleep Quality Index for sleep quality and the Depression Scale of the Center for Epidemiologic Studies for depressive symptoms. Body fatness was the sum of triceps and subscapular skinfolds. Structural equation modelling was used to evaluate associations among these comorbidities.

RESULTS

Social anxiety was directly and positively associated with depressive symptoms, poor sleep quality and body fatness (β = 0.316 standard deviations [SD]; β = 0.299 SD; β = 0.072 SD, respectively). Moreover, social anxiety was indirectly associated with depressive symptoms via poor sleep quality (β = 0.113 SD). Poor sleep quality was directly associated with depressive symptoms (β = 0.377 SD). We did not observe a significant relationship of poor sleep quality and depressive symptoms with body fatness.

LIMITATIONS

This is a cross-sectional study; therefore, we cannot infer causality in the interpretation of the findings.

CONCLUSIONS

Social anxiety seemed to play pivotal role in adolescents' health, since it was associated with poor sleep quality, depressive symptoms and body fatness. Interventions targeting sleep quality, depressive symptoms and body fatness in adolescents should designate relevant effort addressing social anxiety.