Effect of clonidine on plasma ACTH, cortisol and melatonin in children

Melatonin use in the pediatric population: an evolving global concern

BACKGROUND

The impact of melatonin on pediatric populations has not yet been widely researched. This narrative review is intended to summarize the current literature regarding the efficacy and safety of melatonin for children and potential pitfalls in its clinical use, in order to assist pediatric practitioners in making evidence-based recommendations that serve the best interests of their patients and families.

DATA SOURCES

A literature review of melatonin in the pediatric population was conducted using PubMed search terms: melatonin, pediatrics, child/adolescent.

RESULTS

Melatonin use in the pediatric population world-wide has increased significantly over the past several decades. While a number of studies, largely in children with neurodevelopmental disorders with insomnia, have suggested that melatonin is generally safe and well-tolerated, a similar body of evidence is overall lacking for typically developing children and prospective studies regarding long-term adverse events are lacking. In addition, recent studies have raised concerns regarding the variable content of melatonin in over-the-counter products, as well as safety issues relating to accidental ingestions.

CONCLUSIONS

Due to a number of concerns regarding inappropriate use, lack of efficacy and safety data across pediatric populations and variability in actual content, melatonin should be used with caution in children and only under medical supervision.

Effects and mechanisms of perioperative medications on the hypothalamic pituitary adrenal response to surgical injury: A narrative review

The adrenal gland is a vital endocrine organ, and adrenal steroid synthesis and secretion are closely regulated by the hypothalamic-pituitary-adrenal (HPA) axis in response to various stimuli. Surgery or trauma can activate the HPA axis and induce the secretion of cortisol. Different cortisol responses vary with the grade of surgery. Perioperative medications have the potential to decrease the cortisol level in the body, and both excessive and insufficient cortisol levels after surgery are disadvantageous. The effect of perioperative medications on the HPA response to surgery can be divided into three levels: "adrenal insufficiency (AI)", "stress response inhibition", and "uncertainty". The clinical presentation of AI includes fatigue, nausea, vomiting, abdominal pain, muscle cramps, hypotension, hypovolemic shock and prerenal failure, which may result in fatal consequences. Stress response inhibition can reduce postoperative complications, such as pain and cognitive dysfunction. This is protective to patients during perioperative and postoperative periods. The aim of the present review is to shed light on current evidence regarding the exact effects and mechanisms of perioperative medications on the HPA response to surgical injury and provide the applicable guidance on clinical anesthesia.

Behavior Changes Associated with Metabolic Disease of Dogs and Cats

Like many physical disorders, the clinical signs associated with metabolic diseases affecting thyroid, adrenal, and pancreatic function are reflective of nonspecific changes in behavior. Additionally, patients who have underlying disorders associated with fear, anxiety, stress, conflict, and/or panic may be under treatment with medications that alter basal thyroid, glucose, and cortisol levels. Through reinforcement and punishment of behaviors associated with clinical signs caused by organic or iatrogenic endocrine disease, behaviors can be perpetuated and become persistent patterns. Screening all patients presenting with a primary behavior complaint or those with behavioral clinical signs of endocrine diseases is essential. Alleviating stress immediately while working up or treating metabolic disease reduces suffering and may stave off the adoption of behavior patterns more permanently.

Is Melatonin the "Next Vitamin D"?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements

Melatonin has become a popular dietary supplement, most known as a chronobiotic, and for establishing healthy sleep. Research over the last decade into cancer, Alzheimer's disease, multiple sclerosis, fertility, PCOS, and many other conditions, combined with the COVID-19 pandemic, has led to greater awareness of melatonin because of its ability to act as a potent antioxidant, immune-active agent, and mitochondrial regulator. There are distinct similarities between melatonin and vitamin D in the depth and breadth of their impact on health. Both act as hormones, affect multiple systems through their immune-modulating, anti-inflammatory functions, are found in the skin, and are responsive to sunlight and darkness. In fact, there may be similarities between the widespread concern about vitamin D deficiency as a "sunlight deficiency" and reduced melatonin secretion as a result of "darkness deficiency" from overexposure to artificial blue light. The trend toward greater use of melatonin supplements has resulted in concern about its safety, especially higher doses, long-term use, and application in certain populations (e.g., children). This review aims to evaluate the recent data on melatonin's mechanisms, its clinical uses beyond sleep, safety concerns, and a thorough summary of therapeutic considerations concerning dietary supplementation, including the different formats available (animal, synthetic, and phytomelatonin), dosing, timing, contraindications, and nutrient combinations.

The Role of Dexmedetomidine in Tumor-Progressive Factors in the Perioperative Period and Cancer Recurrence: A Narrative Review

Dexmedetomidine, a specific α2 adrenergic receptor agonist, is highly frequently used in the perioperatively for its favorable pharmacology, such as mitigating postoperative cognitive dysfunction. Increasing attention has been recently focused on the effect of whether dexmedetomidine influences cancer recurrence, which urges the discussion of the role of dexmedetomidine in tumor-progressive factors. The pharmacologic characteristics of dexmedetomidine, the tumor-progressive factors in the perioperative period, and the relationships between dexmedetomidine and tumor-progressive factors were described in this review. Available evidence suggests that dexmedetomidine could reduce the degree of immune function suppression, such as keeping the number of CD3+ cells, NK cells, CD4+/CD8+ ratio, and Th1/Th2 ratio stable and decreasing the level of proinflammatory cytokine (interleukin 6 and tumor necrosis factor-alpha) during cancer operations. However, dexmedetomidine exhibits different roles in cell biological behavior depending on cancer cell types. The conclusions on whether dexmedetomidine would influence cancer recurrence could not be currently drawn for the lack of strong clinical evidence. Therefore, this is still a new area that needs further exploration.

The first report of clonidine in vivo/in vitro effects on infertile women with polycystic ovary syndrome (in vivo/in vitro study)

The sympathetic nervous system (SNS) is hyperactive in women with polycystic ovary syndrome (PCOS). This study was designed in two sections: in vivo/in vitro with clonidine as the alpha-2 adrenoceptor (ADR-α₂) agonist for modulating this hyperactivity. Eighty women with PCO participated in this randomised clinical trial (in vivo). A clonidine (0.1 mg) tablet was given twice a day for two months. Polycystic ovary morphology (PCOM) and pregnancy rate were the main outcome measurements. In the candidates for in vitro fertilisation (IVF), clonidine was added to the culture medium during IVF for two study groups (PCO-clonidine/PCO-without) and two control groups (egg donors-clonidine/egg donors-without). Our results showed that the pregnancy rate significantly was higher in the study group (p = .002). The mRNA expression of ADR-α₁ and ADR-β₂ in PCO was higher than control group (p value <.001). But ADR-α₁ expression in PCO-clonidine group decreased (p value = .042), the same as ADR-α₂ expression. The intensity of this effect showed a pattern for ADR-α₁<ADR-β₂<ADR-α₂. Increase of antral follicle count (AFC) growth and pregnancy rate indicate the significant role of ADR-α₂ in PCOS. Clonidine reduced gene expression and protein levels, confirming the above results. These results would aid in pharmacological treatments, as well as assisted reproductive technologies (ARTs).Impact StatementWhat is already known on this subject? In women with PCOS, sympathetic nerve activity is higher than in healthy women. Clonidine is widely used as an alpha-2 presynaptic adrenoceptor (autoreceptor) agonist to modulate the output of the sympathetic nervous system (SNS). Our in vivo/in vitro results showed that the optimal dose of clonidine can increase the oocyte maturity and pregnancy rate in PCO women. This finding was also confirmed by the results in cumulus cell culture.What do the results of this study add? The results of administration of 0.2 mg of clonidine (in vivo) for oocyte maturation and pregnancy rate confirms the in vitro response in the cumulus cell culture of PCO women's follicle.What are the implications of these findings for clinical practice and/or further research? These findings can be used in pharmacological treatment of anovulation and assisted reproductive technology (ART).

Factors Disrupting Melatonin Secretion Rhythms During Critical Illness

OBJECTIVES

The circadian system modulates many important physiologic processes, synchronizing tissue-specific functions throughout the body. We sought to characterize acute alterations of circadian rhythms in critically ill patients and to evaluate associations between brain dysfunction, systemic multiple organ dysfunction, environmental stimuli that entrain the circadian rhythm (zeitgebers), rest-activity rhythms, and the central circadian rhythm-controlled melatonin secretion profile.

DESIGN

Prospective study observing a cohort for 24-48 hours beginning within the first day of ICU admission.

SETTING

Multiple specialized ICUs within an academic medical center.

PATIENTS

Patients presenting from the community with acute onset of either intracerebral hemorrhage as a representative neurologic critical illness or sepsis as a representative systemic critical illness. Healthy control patients were studied in using modified constant routine in a clinical research unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Light, feeding, activity, medications, and other treatment exposures were evaluated along with validated measures of encephalopathy (Glasgow Coma Scale), multiple organ system function (Sequential Organ Failure Assessment score), and circadian rhythms (profiles of serum melatonin and its urinary metabolite 6-sulphatoxymelatonin). We studied 112 critically ill patients, including 53 with sepsis and 59 with intracerebral hemorrhage. Environmental exposures were abnormal, including light (dim), nutritional intake (reduced or absent and mistimed), and arousal stimuli (increased and mistimed). Melatonin amplitude and acrophase timing were generally preserved in awake patients but dampened and delayed with increasing encephalopathy severity. Melatonin hypersecretion was observed in patients exposed to catecholamine vasopressor infusions, but unaffected by sedatives. Change in vasopressor exposure was the only factor associated with changes in melatonin rhythms between days 1 and 2.

CONCLUSIONS

Encephalopathy severity and adrenergic agonist medication exposure were the primary factors contributing to abnormal melatonin rhythms. Improvements in encephalopathy and medical stabilization did not rapidly normalize rhythms. Urinary 6-sulphatoxymelatonin is not a reliable measure of the central circadian rhythm in critically ill patients.

The immunomodulatory mechanism of dexmedetomidine

Dexmedetomidine has been increasingly introduced into the perioperative care of surgical patients. Because a subset of anesthetics/sedatives are immunomodulatory, it is critical to understand the role of dexmedetomidine in our host immune functions. Here we reviewed the role of dexmedetomidine in different immune cells. We also reviewed published clinical articles that described the role of dexmedetomidine in organ injury, cancer surgery, and infection. In animal studies, dexmedetomidine attenuated organ injury. In clinical studies, dexmedetomidine was associated with an improvement in outcomes in cardiac surgery and transplant surgery. However, there is a paucity in research examining how dexmedetomidine is associated with these outcomes. Further studies are needed to understand its clinical application from immunological standpoints.

Melatonin-Measurement Methods and the Factors Modifying the Results. A Systematic Review of the Literature

Melatonin plays an important role in regulating the sleep-wake cycle and adaptation to environmental changes. Concentration measurements in bioliquids such as serum/plasma, saliva and urine are widely used to assess peripheral rhythm. The aim of the study was to compare methods and conditions of determinations carried out with the identification of factors potentially affecting the measurements obtained. We have identified a group of modifiable and unmodifiable factors that facilitate data interpretation. Knowledge of modifiers allows you to carefully plan the test protocol and then compare the results. There is no one universal sampling standard, because the choice of method and biofluid depends on the purpose of the study and the research group.

The use of natural health products by paediatric patients in respite care

OBJECTIVES

To determine the use and potential interactions of natural health products (NHPs) with conventional medications in children with life-limiting illnesses.

METHODS

The present study was a retrospective medical record review of palliative care patients <18 years of age who were admitted for respite care to a Canadian paediatric hospice between January 1, 2008 and December 31, 2013. The NHPs were identified according to Health Canada's inclusion criteria.

RESULTS

A total of 106 children were included in the present study. Eighty-two (77.4%) had used one or more NHPs: 60 (56%) used vitamins and minerals; 45 (42.5%) used other products including probiotics, omega-3, organic acids and essential fatty acids; 34 (32.1%) used everyday consumer products; 12 (11.3%) used herb or plant-based remedies; and one (0.9%) used homeopathic remedies. Thirty-nine potential NHP-medication and 10 potential NHP-NHP interactions were identified. A considerable number of patients (n=54) used at least one medication and NHP, or two NHPs with potential interactions. The most common type of interaction was pharmacokinetic: decreasing blood concentrations of the medication, NHP or both (43.9% of NHP users); and enhancing the blood concentration of an NHP for NHP-NHP interactions (22% of NHP users).

CONCLUSION

A high proportion of patients in respite care use NHPs. Most used NHPs and medications that have potential interactions, although there were no adverse clinical manifestations in the present study. It is important to educate health care professionals about NHPs, the evidence available and lack thereof. This could reduce the most serious interactions and improve the alliance between parents and health care providers to balance the potential risks and benefits of NHPs.

Melatonin in perioperative medicine: Current perspective

Melatonin, a new addition to the armamentarium of anesthesiologist, has some unique properties that are highly desirable in routine peri-operative care. Available clinical data show that preoperative melatonin is as effective as benzodiazepines in reducing preoperative anxiety with minimal action on psychomotor performance and sleep wake cycle. It may be considered as a safe and effective alternative of benzodiazepines as preoperative anxiolytic. It may have opioid sparing effect, may reduce intraocular pressure, and have role in prevention of postoperative delirium. The short-term administration of melatonin is free from significant adverse effects also.

Perioperative melatonin use

Melatonin is a substance chiefly produced by the pineal gland and has a key role in the sleep-wake cycle. It also has an important antioxidant role. Exogenous melatonin has a short half-life and is available in a range of preparations. Newer analogues targeted for the recently discovered melatonin MT1 and MT2 receptors have also been developed. Exogenous melatonin is used as a resynchronisation agent in jet lag and for other sleep disturbances. Perioperatively, melatonin has been used as a premedicant, sedative and analgesic. It decreases paediatric emergence delirium. The antioxidant properties of melatonin are being investigated for use in sepsis and reperfusion injuries. It would appear that patients on melatonin supplements should continue taking them perioperatively because there may be benefits. Melatonin and its analogues will be increasingly encountered in the perioperative setting.

Modulation of stress by imidazoline binding sites: implications for psychiatric disorders

In this review, we present evidence for the involvement of imidazoline binding sites (IBS) in modulating responses to stress, through central control of monoaminergic and hypothalamo-pituitary-adrenal (HPA) axis activity. Pharmacological and physiological evidence is presented for differential effects of different IBS subtypes on serotoninergic and catecholaminergic pathways involved in control of basal and stress-stimulated HPA axis activity. IBS ligands can modulate behavioural and neuroendocrine responses in animal models of stress, depression and anxiety, and a body of evidence exists for alterations in central IBS expression in psychiatric patients, which can be normalised partially or fully by treatment with antidepressants. Dysfunction in monoaminergic systems and the HPA axis under basal and stress-induced activation has been extensively reported in psychiatric illnesses. On the basis of the literature, we suggest a potential therapeutic role for selective IBS ligands in the treatment of depression and anxiety disorders.

Drugs and HPA axis

This paper outlines the interferences of the most widely used drugs with hypothalamo-pituitary-adrenal function and the related laboratory parameters, with the purpose of providing practical help to clinicians during testing for hypo- or hypercortisolemic states.

Melatonin: possible implications for the postoperative and critically ill patient

There is increasing interest in the hormone melatonin in postoperative and critically ill patients. The roles of melatonin in the regulation of the sleep-wake cycle, resetting of circadian rhythm disturbances and its extensive antioxidant activity have potential applications in these patient groups. The interaction between melatonin and the stresses of surgery and critical illness are explored in the context of circadian rhythms, sleep disorders and delirium. The antioxidant activity is discussed in terms of the reduction of ischaemic reperfusion injury, prevention of multi-organ failure and treatment of sepsis. Unfortunately, there is currently insufficient evidence that exogenous melatonin is effective in preventing or treating postoperative delirium. Similarly, in the critically ill patient, sleep disorders are associated with disrupted melatonin circadian secretion, but there is a paucity of data to support routine exogenous melatonin supplementation. More clinical evidence to confirm the potential benefits of melatonin therapy is required before it can be routinely used in the postoperative or critically ill patient.

Characterization of nocturnal ultradian rhythms of melatonin in children with growth hormone-dependent and independent growth delay

To assess the existence of a possible nocturnal ultradian rhythm of melatonin in children, we analyzed 28 pediatric patients (mean age, 9.08 +/- 2.2 yr) with GH-dependent and GH-independent growth delay. Plasma melatonin was measured by RIA in children sampled every 30 min between 2100-0900 h. Statistical analysis consisted of cluster analysis to examine the presence of peaks and troughs. The pattern of melatonin levels was related to the cause of growth delay, although the means of the nocturnal concentrations of melatonin were similar in all children. Interestingly, children with a GH deficit showed a nearly normal melatonin profile, whereas children with normal GH values but abnormal growth displayed atypical profiles of melatonin. The results also prove the existence of an ultradian rhythm of melatonin in most of the patients studied. The ultradian rhythm of melatonin in children was characterized by irregular interburst intervals, thus differing from the rhythm previously described in adults that had an almost constant pulse frequency. Moreover, the existence of low and high melatonin producers was revealed in the study, a feature unrelated to the cause of growth delay. The group of children with a GH deficit showed the lowest values of integrated melatonin production and of the area of peaks and troughs. These results prove that children exhibit an ultradian rhythm of melatonin like that in adults. Whereas it is not clear whether the episodic production of melatonin is required for its biological actions, the existence of irregular pulses may reflect endocrine influences at this age and/or the immaturity of the intrinsic pulse generator.