Treatment of pruritus with topically applied opiate receptor antagonist

Functional magnetic resonance imaging in prurigo nodularis: A call to study neural sensitization phenomena

Prurigo nodularis is a chronic pruritic, inflammatory skin condition characterized by nodular skin lesions in a typical distribution pattern caused by various dermatologic and/or nondermatologic conditions. In recent years, significant advances have been made in the understanding of the cutaneous pathophysiology of prurigo nodularis, resulting in novel treatment options such as interleukin-4, -13, -17, and -31 or Janus kinase inhibitors. Many aspects of the neurophysiology are largely unknown, including the processing in the central structural and functional network involved in prurigo nodularis. Functional neuroimaging allows noninvasive assessment of brain function and structure. Due to its high spatial resolution and temporal precision, functional magnetic resonance imaging has proven to be a suitable method for exploring neural mechanisms and assessing pharmacologic effects in dermatologic research. In this systematic review, the current knowledge of functional magnetic resonance imaging in the context of prurigo nodularis and its centrally active treatment options is summarized.

Exploring itch in hidradenitis suppurativa with lessons from atopic dermatitis and psoriasis

Itch is a prominent symptom in many cutaneous disorders, including atopic dermatitis (AD), prurigo nodularis, and psoriasis. Itch is also a common but overlooked concern in patients with hidradenitis suppurativa (HS). Currently, the mechanisms underlying itch in HS remain unclear. To gain a better understanding, we reviewed the literature on pruritus in HS and other itch-predominant disorders, AD, and psoriasis. In HS, psoriasis, and AD, we found that itch often co-localized with pain and occurred more frequently at night. Furthermore, itch was found to negatively affect sleep and increase the risk for comorbid psychiatric disorders in HS, psoriasis, and AD. However, HS-, psoriasis-, and AD-related itch differ in temporality. Itch in AD is often described as chronic, while itch in HS and psoriasis is often described as episodic. HS-associated itch is likely multifactorial, and several mechanisms have been proposed including peripheral sensitization, central sensitization, and neuroinflammation. Prior studies in HS highlight enhanced IgE production and a dense infiltration of mast cells, along with a variety of cytokines and chemokines. Furthermore, alterations in the skin microbiome may contribute to itch in HS. To date, few therapies have been studied to treat itch in HS. Given the efficacy of several biologics and small molecules in treating itch in AD and psoriasis, similar agents may be explored in future HS studies. Alternative therapies to target neurological and psychiatric contributions to itch may include anticonvulsants, cannabinoids, and nonpharmacological treatments. In conclusion, pathomechanisms of itch in HS remain to be fully elucidated. However, we can draw on lessons from other pruritic disorders to begin addressing the symptom of it and identify important questions for future study.

Adjunctive Management of Itch in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin condition that can be difficult to treat due to a complex etiology and diverse clinical presentations. Itch is the most common symptom associated with AD with profound negative impact on quality of life. Thus, the adjunctive management of itch in patients with AD is needed to control and reduce disease burden. Supplemental treatment options are continuously emerging and undergoing testing in clinical trials. This article summarizes the latest data on topical and systemic adjunctive therapies for AD safety and efficacy in reducing itch.

Impact of pruritus in patients undergoing hemodialysis in Italy: a patient-based survey

BACKGROUND

Itching is an annoying symptom which afflicts patients with chronic renal failure. We aimed to assess the impact and patient's perception and experience of itching in the dialysis population in Italy.

METHODS

A questionnaire was developed by the National Hemodialysis and Dialysis Association of Italy (ANED) and administered to 996 hemodialysis recipients across 153 Italian dialysis centers. The main outcomes investigated by the questionnaire were patients' satisfaction on answers regarding the nature of itching; continuing to talk about itching with the nephrologist; beliefs about resolution of itching.

RESULTS

A total of 1903 patients from 153 centers responded to the questionnaire. Patients who responded had a mean age of 67.9 ± 13.8 years (63.9% male) and were stratified by itch discomfort graded as mild (35.9%), moderate (29.6%), and severe (34.4%). Severe itching disrupted patients' daily lives, strained their relationships, caused anxiety, and diminished their quality of life. Patients with severe itch were more likely to talk about it with dialysis staff and to undertake dermatological visits. However, only 18.0% of patients reporting severe itching found the clinicians' responses satisfactory, compared to 49.1% of mild itch patients. Those who continued talking to nephrologists about itching received more satisfactory response. However, 40.8% believed itching could not be alleviated and were less likely to discuss it with nephrologists.

CONCLUSIONS

There is an intricate relationship between the severity of itching, patient perceptions, and healthcare communication among hemodialysis patients. A substantial proportion of patients experiencing severe itching expressed feelings of resignation, highlighting the pressing need for enhanced clinician-patient communication.

Topical Treatments in Atopic Dermatitis: An Expansive Review

Atopic dermatitis (AD) is a common inflammatory skin condition found worldwide. It impacts patient quality of life (QoL) and is thought to arise as an inflammatory response to epidermal barrier dysfunction and hypersensitivity. AD can lead to large out-of-pocket costs and increased healthcare expenses over a lifetime. An analysis of all randomized control trials conducted since 1990 on topical therapies for AD were reviewed, including 207 trials in the final analysis. It was found that an average of 226 patients were enrolled over 2.43 arms. Common topical treatments included corticosteroids, calcineurin inhibitors, JAK inhibitors, and phosphodiesterase inhibitors. The most utilized tools to identify treatment efficacy were the EASI, IGA, SCORAD, and PGA. There was a paucity of data on trials that evaluated efficacy, QoL, and cost of treatment simultaneously. This review highlights the need for comprehensive trials that evaluate multiple aspects of treatment, including financial cost and QoL impact, to ensure each patient has the best treatment modality for the management of their AD.

An update on mechanisms of pruritus and their potential treatment in primary cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas (CTCL), which include mycosis fungoides (MF) and Sézary syndrome (SS), are a group of lymphoproliferative disorders characterized by clonal accumulation of neoplastic T-lymphocytes in the skin. Severe pruritus, one of the most common and distressing symptoms in primary CTCL, can significantly impair emotional well-being, physical functioning, and interpersonal relationships, thus greatly reducing quality of life. Unfortunately, effectively managing pruritus remains challenging in CTCL patients as the underlying mechanisms are, as of yet, not fully understood. Previous studies investigating the mechanisms of itch in CTCL have identified several mediators and their corresponding antagonists used for treatment. However, a comprehensive overview of the mediators and receptors contributing to pruritus in primary CTCL is lacking in the current literature. Here, we summarize and review the mediators and receptors that may contribute to pruritus in primary CTCL to explore the mechanisms of CTCL pruritus and identify effective therapeutic targets using the PubMed and Web of Science databases. Studies were included if they described itch mediators and receptors in MF and SS. Overall, the available data suggest that proteases (mainly tryptase), and neuropeptides (particularly Substance P) may be of greatest interest. At the receptor level, cytokine receptors, MRGPRs, and TRP channels are most likely important. Future drug development efforts should concentrate on targeting these mediators and receptors for the treatment of CTCL pruritus.

Pathomechanism of Pruritus in Psoriasis and Atopic Dermatitis: Novel Approaches, Similarities and Differences

Pruritus is defined as an unpleasant sensation that elicits a desire to scratch. Nearly a third of the world's population may suffer from pruritus during their lifetime. This symptom is widely observed in numerous inflammatory skin diseases-e.g., approximately 70-90% of patients with psoriasis and almost every patient with atopic dermatitis suffer from pruritus. Although the pathogenesis of atopic dermatitis and psoriasis is different, the complex intricacies between several biochemical mediators, enzymes, and pathways seem to play a crucial role in both conditions. Despite the high prevalence of pruritus in the general population, the pathogenesis of this symptom in various conditions remains elusive. This review aims to summarize current knowledge about the pathogenesis of pruritus in psoriasis and atopic dermatitis. Each molecule involved in the pruritic pathway would merit a separate chapter or even an entire book, however, in the current review we have concentrated on some reports which we found crucial in the understanding of pruritus. However, the pathomechanism of pruritus is an extremely complex and intricate process. Moreover, many of these signaling pathways are currently undergoing detailed analysis or are still unexplained. As a result, it is currently difficult to take an objective view of how far we have come in elucidating the pathogenesis of pruritus in the described diseases. Nevertheless, considerable progress has been made in recent years.

Angelica Yinzi Alleviates Pruritus-Related Atopic Dermatitis through Skin Repair, Antioxidation, and Balancing Peripheral μ- and κ-opioid Receptors

Background

Angelica Yinzi (AYZ) is a Chinese traditional herbal formula reported to attenuate itches and inflammation caused by atopic dermatitis (AD). However, the underlying mechanism of AYZ in the attenuation of itchiness and inflammation remains unknown.

Objective

This study investigated the mechanism of AYZ in reducing itchiness in mice with 1-chloro-2,4-dinitrobenzene- (DNCB-)-induced atopic dermatitis.

Methods

Hematoxylin and eosin (H&E) and toluidine blue staining were used to evaluate pathological changes in skin tissue, while an enzyme-linked immunosorbent assay (ELISA) was used to assess the cytokine levels in the skin. After that, qRT-PCR was performed to determine the mRNA levels of cytokines in the skin. Immunofluorescence and western blotting analysis were further used to assess µ-opioid receptor (MOR) expression and immunohistochemistry to assess the p-ERK, p-AKT, and κ-opioid receptor (KOR).

Results

The AYZ treatment alleviated the AD clinical symptoms, including decreasing the scratching frequency, the ear thickness, and the infiltration of mast cells, lymphocytes, inflammatory cells, and mononuclear cells. In addition, AYZ inhibited the expression of interleukin (IL)-13, thymic stromal lymphopoietin (TSLP), and reduced neuraminidase (NA), corticotropin-releasing factor (CRF), and reactive oxygen species (ROS) expression. Markers involved in itches, such as p-ERK and p-AKT, were significantly downregulated following AYZ treatment. Besides, AYZ significantly increased MOR expression and downregulated KOR in the epidermis and spinal cord.

Conclusion

Our findings imply that AYZ ameliorates pruritus-related AD through skin repair, antioxidation, and balancing peripheral MOR and KOR. The findings in this study lay a theoretical foundation for the control mechanism of peripheral itch.

Efficacy and Safety of Fig (Ficus carica L.) Leaf Tea in Adults with Mild Atopic Dermatitis: A Double-Blind, Randomized, Placebo-Controlled Preliminary Trial

Atopic dermatitis (AD) is a chronic, recurrent pruritic skin disease with repeated remissions and exacerbations. Various factors, such as allergies, skin conditions and lifestyle, combine to cause AD, making it difficult to cure completely. Although AD symptoms are suppressed with medications, this is a long-term effort and burden on patients. Thus, safer drugs and alternatives are needed. We previously found that consumption of tea prepared from fig (Ficus carica L.) leaves alleviated allergy and AD symptoms in cultured cells and animals. Therefore, here, we conducted a double-blind, randomized, controlled study in patients with mild AD to evaluate the safety and AD-relieving effects of prolonged consumption of fig leaf tea. Positive effects of fig leaf tea consumption were confirmed in 14 of 15 participants. Eczema Area and Severity Index values were significantly lowered in the fig leaf tea-treated group than in the placebo-treated group. The effect weakened 4 weeks after the end of the intervention, suggesting that continued intake of fig leaf tea was effective. Further assessments confirmed the safety of fig leaf tea consumption and revealed no variations that might pose a health hazard. Therefore, we postulate that fig leaf tea is a natural and safe therapeutic option for AD.

Druggable Targets and Compounds with Both Antinociceptive and Antipruritic Effects

Pain and itch are both important manifestations of various disorders, such as herpes zoster, atopic dermatitis, and psoriasis. Growing evidence suggests that both sensations have shared mediators, overlapping neural circuitry, and similarities in sensitization processes. In fact, pain and itch coexist in some disorders. Determining pharmaceutical agents and targets for treating pain and itch concurrently is of scientific and clinical relevance. Here we review the neurobiology of pain and itch and discuss the pharmaceutical targets as well as novel compounds effective for the concurrent treatment of these sensations.

Peripheral itch sensitization in atopic dermatitis

Atopic dermatitis is a skin disorder caused by skin dryness and barrier dysfunction, resulting in skin inflammation and chronic itch (or pruritus). The pathogenesis of atopic dermatitis is thought to be initiated by a lowering of the itch threshold due to dry skin. This lowering of the itch threshold is at least partially due to the increase in intraepidermal nerve fibers and sensitization of sensory nerves by interleukin (IL)-33 produced and secreted by keratinocytes. Such skin is easily prone to itch due to mechanical stimuli, such as rubbing of clothing and chemical stimuli from itch mediators. In patients with atopic dermatitis, once itch occurs, further itch is induced by scratching, and the associated scratching breaks down the skin barrier. Disruption of the skin barrier allows entry into the epidermis of external foreign substances, such as allergens derived from house dust mites, leading to an increased induction of type 2 inflammatory responses. As a result, type 2 cytokines IL-4, IL-13, and IL-31 are mainly secreted by Th2 cells, and their action on sensory nerve fibers causes further itch sensitization. These sequences of events are thought to occur simultaneously in patients with atopic dermatitis, leading to a vicious itch-scratch cycle. This vicious cycle becomes a negative spiral that leads to disease burden. Therefore, controlling itch is essential for the treatment of atopic dermatitis. In this review, we summarize and discuss advances in the mechanisms of peripheral itch sensitization in atopic dermatitis, focusing on skin barrier-neuro-immune triadic connectivity.

Opioidergic Signaling-A Neglected, Yet Potentially Important Player in Atopic Dermatitis

Atopic dermatitis (AD) is one of the most common skin diseases, the prevalence of which is especially high among children. Although our understanding about its pathogenesis has substantially grown in recent years, and hence, several novel therapeutic targets have been successfully exploited in the management of the disease, we still lack curative treatments for it. Thus, there is an unmet societal demand to identify further details of its pathogenesis to thereby pave the way for novel therapeutic approaches with favorable side effect profiles. It is commonly accepted that dysfunction of the complex cutaneous barrier plays a central role in the development of AD; therefore, the signaling pathways involved in the regulation of this quite complex process are likely to be involved in the pathogenesis of the disease and can provide novel, promising, yet unexplored therapeutic targets. Thus, in the current review, we aim to summarize the available potentially AD-relevant data regarding one such signaling pathway, namely cutaneous opioidergic signaling.

Overcoming drug delivery barriers and challenges in topical therapy of atopic dermatitis: A nanotechnological perspective

Atopic dermatitis (AD) is an inflammatory disorder centered around loss of epidermal barrier function, and T helper 2 (Th2) immune responses. The current understanding of disease heterogeneity and complexity, limits the rational use of existing topical, systemic therapeutic agents, but paves way for development of advanced therapeutic agents. Additionally, advanced nanocarriers that deliver therapeutics to target cells, seem to offer a promising strategy, to overcome intrinsic limitations and challenges of conventional, and traditional drug delivery systems. Ever-evolving understanding of molecular target sites and complex pathophysiology, adverse effects of current therapeutic options, inefficient disease recapitulation by existing animal models are some of the challenges that we face. Also, despite limited success in market translatibility, nanocarriers have demonstrated excellent preclinical results and have been extensively studied for AD. Detailed research on behavior of nanocarriers in different patients and tailored therapy to account for phenotypic variability of the disease are the new research avenues that we look forward to.

2020 guidelines for the diagnosis and treatment of cutaneous pruritus

The mechanisms underlying itch are not fully understood. Physicians usually encounter difficulty controlling itch in generalized pruritus. Since only a small percentage of patients with generalized pruritus respond to antihistamines (H₁ receptor antagonists), a variety of itch mediators and mechanisms other than histaminergic signals are considered to be involved in itch for these non-responsive patients. In 2012, we created guidelines for generalized pruritus. Those guidelines have been updated and revised to make some of the definitions, diagnostic terms, and classifications more applicable to daily clinical practice. Cutaneous pruritus as designated in these guidelines is a disease characterized by itch without an observable rash. Generalized pruritus (without skin inflammation) is defined as the presence of itch over a wide area, and not localized to a specific part of the body. This entity includes idiopathic pruritus, pruritus in the elderly, symptomatic pruritus, pregnancy-associated pruritus, drug-induced pruritus, and psychogenic pruritus. Localized pruritus (without skin inflammation) represents fixed itch localized to a specific part of the body, and includes anogenital pruritus, scalp pruritus, notalgia paresthetica, and brachioradial pruritus. These guidelines outline the current concepts and specify the diagnostic methods/treatments for cutaneous pruritus.

Effectiveness of a treatment algorithm for hemodialysis-associated pruritus in terms of changes in medications

Background

Hemodialysis-associated pruritus (HAP) is a serious complication that occurs in 60–80% of hemodialysis patients, which not only decreases quality of life but also worsens prognosis. We have developed a treatment algorithm to take a comprehensive cause-specific approach to HAP and used it at our facility since June 2009. In this treatment algorithm, moisturizers and topical steroids are used depending on skin condition and severity of pruritus; administration of nalfurafine hydrochloride is considered in treatment-resistant cases. If pruritus improves, we attempt to taper topical steroids by switching to lower potency or by dose reduction or discontinuation. Here, we examined the effectiveness of the treatment algorithm over 9 years in terms of changes in medications.

Methods

Subjects were hemodialysis patients who received treatment for HAP at our facility: 89 in May 2009 before introduction of the algorithm, and 131 in April 2013, 164 in October 2014, 190 in October 2015, 181 in October 2016, 215 in October 2017, and 224 patients in October 2018 after its introduction. A questionnaire survey was conducted on the presence of pruritus, severity (using a visual analogue scale [VAS] and Shiratori severity scores), frequency, and insomnia due to pruritus. Changes in medications were investigated using medical records and compared.

Results

The proportion of patients with pruritus decreased significantly from 96.6% in 2009 to 66.8% in 2018 (p < 0.001). Median VAS score significantly decreased from 53.0 mm in 2009 to 24.5 mm in 2018 (p < 0.001), and the proportion of patients with insomnia due to pruritus also significantly decreased from 25.8% in 2009 to 2.2% in 2018 (p < 0.001). The proportion of patients who used moisturizers significantly increased from 34.8 to 89.7% (p < 0.001). The proportion of patients receiving topical steroids decreased from 47.2 to 35.7%, but the difference was not significant (p = 0.085).

Conclusions

The treatment algorithm was shown to be useful for improving HAP, but future challenges were identified, including promoting use of lower potency topical steroids or discontinuation. Further prospective studies are required to confirm the role of each treatment intervention in a comprehensive cause-specific approach to HAP.

Naltrexone for cholestatic itch: a systematic review

BACKGROUND

Cholestatic itch is caused by intrahepatic liver diseases, such as primary biliary cirrhosis and extrahepatic obstruction of the biliary tree, often caused by tumours. The pathophysiology of cholestatic itch is complex and no single treatment has proved definitive. Naltrexone is an opioid receptor antagonist, which reduces central opioidergic tone, believed to be raised in patients with cholestatic pruritus.

AIM

To review and assess the efficacy of oral naltrexone for the treatment of cholestatic itch.

METHODS

Search of electronic databases, grey literature, clinical trials registries and handsearching for studies including naltrexone for cholestatic itch. Full papers were obtained if relevant and studies graded.

RESULTS

Thirteen papers were included in the analysis, including three randomised controlled trials, one controlled clinical trial, one open-label pilot study, seven case reports and one retrospective notes review. All studies found naltrexone to be effective in relieving pruritus. In all five studies performing statistical analysis, naltrexone significantly reduced pruritus compared with baseline. 37% of patients reported side effects, notably opioid withdrawal-type reactions and recurrence of previous pain, from all pathologies.

CONCLUSIONS

Oral naltrexone therapy helps relieve cholestatic itch and although it should be used with caution in patients using exogenous opioids for analgesia, it should be considered when treating refractory pruritus in patients with end-stage liver disease.

Intractable Itch in Atopic Dermatitis: Causes and Treatments

Itch or pruritus is the hallmark of atopic dermatitis and is defined as an unpleasant sensation that evokes the desire to scratch. It is also believed that itch is a signal of danger from various environmental factors or physiological abnormalities. Because histamine is a well-known substance inducing itch, H₁-antihistamines are the most frequently used drugs to treat pruritus. However, H₁-antihistamines are not fully effective against intractable itch in patients with atopic dermatitis. Given that intractable itch is a clinical problem that markedly decreases quality of life, its treatment in atopic dermatitis is of high importance. Histamine-independent itch may be elicited by various pruritogens, including proteases, cytokines, neuropeptides, lipids, and opioids, and their cognate receptors, such as protease-activated receptors, cytokine receptors, Mas-related G protein-coupled receptors, opioid receptors, and transient receptor potential channels. In addition, cutaneous hyperinnervation is partly involved in itch sensitization in the periphery. It is believed that dry skin is a key feature of intractable itch in atopic dermatitis. Treatment of the underlying conditions that cause itch is necessary to improve the quality of life of patients with atopic dermatitis. This review describes current insights into the pathophysiology of itch and its treatment in atopic dermatitis.

Topical application of sebacoyl dinalbuphine ester-loaded nanostructured lipid carriers alleviate pruritus in scratching mouse model

Sebacoyl dinalbuphine ester (SDE) is a nalbuphine (NA) prodrug capable of biotransformation in vivo and prolong the duration of NA, maximize its effect in pain and pruritus management. However, the large molecular weight, low skin penetration, and stability concerns of SDE make it difficult to be used in local skin delivery. Nanostructured lipid carrier (NLC) is a lipid-based nanoparticulate system that has the potential for formulating SDE in order to promote drug delivery through the skin. The aim of this study was to develop SDE-loaded NLC formulations (SDE-NLC) with good stability, sustained release characteristics, and sufficient antipruritic effect. SDE was successfully encapsulated into NLC and the formulation increased the stability of SDE, enhanced skin penetration through hair follicles, and sustained SDE release during pruritus management. We also demonstrated that topical application of SDE-NLCs significantly reduced the number of scratches in pruritus-induced mice. Both NA and SDE were found in the skin strata, but only NA was detectable in the plasma, indicating rapid conversion of SDE into NA. All results demonstrated that SDE-NLC formulation protected SDE from degradation in vitro, while the released prodrug was converted into NA in vivo and extended antipruritic effect. The formulation has the potential of improving the life quality of patients with chronic pruritus.

Substance use disorders and chronic itch

Chronic pruritus is one dermatologic manifestation of an underlying substance use disorder. Recent literature has uncovered similarities between the general neurologic mechanisms of addiction and chronic itch, largely involving activation of the dopaminergic reward circuits within the brain and imbalances between mu and kappa opioid receptor activation. It is likely that the use of specific drugs, like central nervous system stimulants and opioids, results in further activation and imbalances within these pathways, perpetuating both addiction and pruritus simultaneously. Opioid users often present to dermatology clinics with a generalized pruritus, whereas individuals using central nervous system stimulants like cocaine and methylenedioxymethamphetamine (MDMA), as well as legally prescribed drugs like treatments for attention deficit hyperactivity disorder, frequently complain of crawling, delusional infestation-like sensations underneath the skin. Because of these overlapping mechanisms and similar clinical presentations to many other chronically itchy conditions, it is necessary for dermatologists to consider and investigate an underlying substance use disorder to effectively treat these patients.

Small molecule drugs for the treatment of pruritus in patients with atopic dermatitis

Chronic pruritus is a cardinal symptom of the inflammatory skin disease atopic dermatitis (AD). Pathogenic mechanisms in the periphery, spinal cord and the brain have been implicated in AD-related pruritus. Therefore, both systemic and topical administration of drugs could potentially provide relief. Despite efforts to elucidate the mechanisms behind AD-related pruritus and the relative contribution of peripheral nervous system and central nervous system (CNS), specific and successful treatment options have not yet been developed. Several small molecule drugs are currently being investigated to treat AD and AD-related pruritus. These small molecule drugs can be applied systemically but also topically, as they are able to penetrate into the skin due to their small size. Small molecule drugs specifically targeting peripheral itch transmission, e.g. peripherally selective κ-opioid receptors agonists and neurokinin 1 receptors antagonists, have so far been unable to improve AD-related pruritus when applied systemically, possibly because of the lack of CNS activity. Current evidence from clinical and preclinical trials with centrally acting or peripherally selective oral κ-opioid receptors agonists implies that CNS activity is required for an antipruritic effect. CNS activity is, however, directly associated with CNS-mediated side-effects. On the other hand, topical application of small molecules with anti-inflammatory activity such as Janus kinase inhibitors and phosphodiesterase 4 inhibitors, and also of κ-opioid receptor agonists, has shown promising results regarding their ability to reduce AD-related pruritus. In conclusion, topical application of anti-inflammatory compounds appears to be a highly promising strategy for the treatment of AD-related pruritus.

Opioid receptors expression in the skin of haemodialysis patients suffering from uraemic pruritus

BACKGROUND

Uraemic pruritus is a common symptom in patients with chronic kidney disease undergoing haemodialysis (HD) treatment. Etiopathogenesis of uraemic pruritus is complex and not fully explained, but there are reports indicating a possible role of peripheral opioid system in its pathomechanism.

OBJECTIVES

This study was undertaken to analyse the expression of mu- and kappa-opioid receptors in the skin of HD patients with and without uraemic pruritus.

METHODS

Forty patients suffering from chronic kidney disease, treated with haemodialysis (21 pruritic and 19 non-pruritic), were included. The expression of mu- and kappa-opioid receptors in their skin was evaluated with immunohistochemistry.

RESULTS

The significant (P < 0.02) decrease in kappa-opioid receptor expression was shown in the skin of pruritic patients in comparison with the skin of those without itch (1.07 ± 0.62 and 1.66 ± 0.85, respectively). Moreover, there was a significant negative correlation between intensity of pruritus and expression of kappa-opioid receptors (r = -0.63, P = 0.002). There was no difference in the expression of mu-opioid receptor expression in the skin of pruritic and non-pruritic HD patients.

CONCLUSIONS

This study indicates that changes in peripheral opioid system may play an important role in the uraemic itch pathogenesis and that future studies are necessary to fully understand this mechanism.

Interventions for chronic pruritus of unknown origin

BACKGROUND

Pruritus is a sensation that leads to the desire to scratch; its origin is unknown in 8% to 15% of affected patients. The prevalence of chronic pruritus of unknown origin (CPUO) in individuals with generalised pruritus ranges from 3.6% to 44.5%, with highest prevalence among the elderly. When the origin of pruritus is known, its management may be straightforward if an effective treatment for the causal disease is available. Treatment of CPUO is particularly difficult due to its unknown pathophysiology.

OBJECTIVES

To assess the effects of interventions for CPUO in adults and children.

SEARCH METHODS

We searched the following up to July 2019: Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, and trials registries. We checked the reference lists of included studies for additional references to relevant trials.

SELECTION CRITERIA

We sought to include randomised controlled trials and quasi-randomised controlled trials that assessed interventions for CPUO, as defined in category VI ('Other pruritus of undetermined origin, or chronic pruritus of unknown origin') of the International Forum for the Study of Itch (IFSI) classification, in children and adults. Eligible interventions were non-pharmacological or topical or systemic pharmacological interventions, and eligible comparators were another active treatment, placebo, sham procedures, or no treatment or equivalent (e.g. waiting list).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were 'Patient- or parent-reported pruritus intensity' and 'Adverse events'. Our secondary outcomes were 'Health-related quality of life', 'Sleep disturbances', 'Depression', and 'Patient satisfaction'. We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We found there was an absence of evidence for the main interventions of interest: emollient creams, cooling lotions, topical corticosteroids, topical antidepressants, systemic antihistamines, systemic antidepressants, systemic anticonvulsants, and phototherapy. We included one study with 257 randomised (253 analysed) participants, aged 18 to 65 years; 60.6% were female. This study investigated the safety and efficacy of three different doses of oral serlopitant (5 mg, 1 mg, and 0.25 mg, once daily for six weeks) compared to placebo for severe chronic pruritus; 25 US centres participated (clinical research centres and universities). All outcomes were measured at the end of treatment (six weeks from baseline), except adverse events, which were monitored throughout. A pharmaceutical company funded this study. Fifty-five per cent of participants suffered from CPUO, and approximately 45% presented a dermatological diagnosis (atopic dermatitis/eczema 37.3%, psoriasis 6.7%, acne 3.6%, among other diagnoses). We unsuccessfully attempted to retrieve outcome data from study authors for the subgroup of participants with CPUO. Participants had pruritus for six weeks or longer. Total study duration was 10 weeks. Participants who received serlopitant 5 mg may have a greater rate of relief of patient-reported pruritus intensity as measured by the visual analogue scale (VAS; a reduction in VAS score indicates improvement) compared to placebo (126 participants, risk ratio (RR) 2.06, 95% confidence interval (CI) 1.27 to 3.35; low-certainty evidence). We are uncertain of the effects of serlopitant 5 mg compared to placebo on the following outcomes due to very low-certainty evidence: adverse events (127 participants; RR 1.48, 95% CI 0.87 to 2.50); health-related quality of life (as measured by the Dermatology Life Quality Index (DLQI); a higher score indicates greater impairment; 127 participants; mean difference (MD) -4.20, 95% CI -11.68 to 3.28); and sleep disturbances (people with insomnia measured by the Pittsburgh Sleep Symptom Questionnaire-Insomnia (PSSQ-I), a dichotomous measure; 128 participants; RR 0.49, 95% CI 0.24 to 1.01). Participants who received serlopitant 1 mg may have a greater rate of relief of patient-reported pruritus intensity as measured by VAS compared to placebo; however, the 95% CI indicates that there may also be little to no difference between groups (126 participants; RR 1.50, 95% CI 0.89 to 2.54; low-certainty evidence). We are uncertain of the effects of serlopitant 1 mg compared to placebo on the following outcomes due to very low-certainty evidence: adverse events (128 participants; RR 1.45, 95% CI 0.86 to 2.47); health-related quality of life (DLQI; 128 participants; MD -6.90, 95% CI -14.38 to 0.58); and sleep disturbances (PSSQ-I; 128 participants; RR 0.38, 95% CI 0.17 to 0.84). Participants who received serlopitant 0.25 mg may have a greater rate of relief of patient-reported pruritus intensity as measured by VAS compared to placebo; however, the 95% CI indicates that there may also be little to no difference between groups (127 participants; RR 1.66, 95% CI 1.00 to 2.77; low-certainty evidence). We are uncertain of the effects of serlopitant 0.25 mg compared to placebo on the following outcomes due to very low-certainty evidence: adverse events (127 participants; RR 1.29, 95% CI 0.75 to 2.24); health-related quality of life (DLQI; 127 participants; MD -5.70, 95% CI -13.18 to 1.78); and sleep disturbances (PSSQ-I; 127 participants; RR 0.60, 95% CI 0.31 to 1.17). The most commonly reported adverse events were somnolence, diarrhoea, headache, and nasopharyngitis, among others. Our included study did not measure depression or patient satisfaction. We downgraded the certainty of evidence for all outcomes due to indirectness (only 55% of study participants had CPUO) and imprecision. We downgraded outcomes other than patient-reported pruritus intensity a further level due to concerns regarding risk of bias in selection of the reported result and some concerns with risk of bias due to missing outcome data (sleep disturbances only). We deemed risk of bias to be generally low.

AUTHORS' CONCLUSIONS

We found lack of evidence to address our review question: for most of our interventions of interest, we found no eligible studies. The neurokinin 1 receptor (NK1R) antagonist serlopitant was the only intervention that we could assess. One study provided low-certainty evidence suggesting that serlopitant may reduce pruritus intensity when compared with placebo. We are uncertain of the effects of serlopitant on other outcomes, as certainty of the evidence is very low. More studies with larger sample sizes, focused on patients with CPUO, are needed. Healthcare professionals, patients, and other stakeholders may have to rely on indirect evidence related to other forms of chronic pruritus when deciding between the main interventions currently used for this condition.

Synergistic Effect of H1-Antihistamines on Topical Corticosteroids for Pruritus in Atopic Dermatitis: A Systematic Review and Meta-Analysis

Background

Although oral antihistamines (H1-histamine receptor antagonists) are the main treatment option for pruritus in general skin dermatosis, their effect in treating pruritus of atopic dermatitis (AD) has not yet been established.

Objective

We conducted a systematic review and meta-analysis to evaluate the effectiveness of combined therapy of H1-antihistamines and topical steroids.

Methods

We systematically searched MEDLINE, Embase, and CENTRAL databases for articles published from 1967 to 2015. We identified 1,206 studies and assessed their titles, abstract, and full-text. Random effects meta-analysis was used to calculate mean differences (MD) with 95% confidence intervals (CI).

Results

Two studies satisfying the inclusion criteria of antihistamine therapy with mandatory topical steroid use were selected. Comparing antihistamine monotherapy with combination therapy, patients treated with the addition of antihistamine to topical corticosteroids showed a statistically significant clinical improvement (standard MD, −0.24; 95% CI, −0.42 to −0.05; p=0.01).

Conclusion

H1-antihistamines may have a synergistic effect when combined with topical steroids by influencing various associative factors of chronic pruritus in AD.

Therapeutic Potential of Kappa Opioid Agonists

Many original research articles have been published that describe findings and outline areas for the development of kappa-opioid agonists (KOAs) as novel drugs; however, a single review article that summarizes the broad potential for KOAs in drug development does not exist. It is well-established that KOAs demonstrate efficacy in pain attenuation; however, KOAs also have proven to be beneficial in treating a variety of novel but often overlapping conditions including cardiovascular disease, pruritus, nausea, inflammatory diseases, spinal anesthesia, stroke, hypoxic pulmonary hypertension, multiple sclerosis, addiction, and post-traumatic cartilage degeneration. This article summarizes key findings of KOAs and discusses the untapped therapeutic potential of KOAs in the treatment of many human diseases.

The Antipruritic Effect of Phototherapy

Phototherapy is widely used to treat inflammatory skin diseases such as psoriasis and atopic dermatitis. Repeated suberythemogenic doses of UV-light reduce inflammation in these diseases and ultimately may lead to a complete disappearance of cutaneous symptoms for weeks or months. Chronic pruritus is an important and highly distressing symptom of many of these inflammatory skin diseases. Interestingly, pruritus is also reduced or completely abolished by UV-treatment of psoriasis and atopic dermatitis, and sometimes reduction of pruritus is the first indication for skin improvement by phototherapy. The cutaneous nervous system is an integral part of skin anatomy, and free nerve endings of sensory cutaneous nerve fibers reach up into the epidermis getting in close contact with epidermal cells and mediators from epidermal cells released into the intercellular space. Stimulation of “pruriceptors” within this group of sensory nerve fibers generates a neuronal signal eventually transmitted via the dorsal root and the spinal cord to the brain, where it is recognized as “itch”. UV-light may directly affect cutaneous sensory nerve fibers or, via the release of mediators from cells within the skin, indirectly modulate their function as well as the transmission of itch to the central nervous system inducing the clinically recognized antipruritic effect of phototherapy.

C-Terminal Residue of Ultrashort Peptides Impacts on Molecular Self-Assembly, Hydrogelation, and Interaction with Small-Molecule Drugs

Single molecular changes on a tripeptide can have dramatic effects on their self-assembly and hydrogelation. Herein, we explore C-terminal residue variation on two consistent ultrashort peptide backbones, i.e. acetylated-Leu-Ile-Val-Ala-Gly-Xaa and acetylated-Ile-Val-Xaa (Xaa = His, Arg, Asn). The objective of this study is to identify candidates that can form hydrogels for small-molecule drug (SMD) delivery. Haemolysis and cytotoxicity (with human adipose-derived mesenchymal stem cells) assays showed that the new soluble peptides (Xaa = His, Arg) are cytocompatible. Gelation studies showed that all but acetylated-Ile-Val-Arg could gel under physiological conditions. Longer peptidic backbones drive self-assembly more effectively as reflected in field emission scanning electron microscopy (FESEM) and circular dichroism spectroscopy studies. Rheological studies revealed that the resultant hydrogels have varying stiffness and yield stress, depending on the backbone and C-terminal residue. Visible spectroscopy-based elution studies with SMDs (naltrexone, methotrexate, doxorubicin) showed that besides the C-terminal residue, the shape of the SMD also determines the rate and extent of SMD elution. Based on the elution assays, infrared spectroscopy, and FESEM, we propose models for the peptide fibril-SMD interaction. Our findings highlight the importance of matching the molecular properties of the self-assembling peptide and SMD in order to achieve the desired SMD release profile.

Itching, chloroquine, and malaria: a review of recent molecular and neuroscience advances and their contribution to mechanistic understanding and therapeutics of chronic non-histaminergic pruritus

Chloroquine (CQ) is an antimalarial drug that elicits severe pruritus in black Africans with malaria fever. This acute itching (2-7 days duration) exhibits age dependency and a racial and genetic predilection. CQ itch is non-histaminergic, which makes it both a good model and a tool to probe the mechanisms of chronic itch. This review focuses on recently discovered mechanisms, neuroscience, mediators, and receptors that are implicated in molecular studies of CQ pruritus. CQ pruritus mechanisms are also compared to that of itching following other systemic diseases, such as chronic kidney disease, chronic liver disease, skin disorders, and burns. There are striking similarities between CQ itching pathways and other chronic itch secondary to systemic disease with or without skin lesions, which have not been previously highlighted. Prominent among these are the shared roles of skin, neural and spinal μ opiate receptors, kappa opiate receptor, nitric oxide, serotonin via 5HT1B/D receptors, cytokines, especially interleukins, and tumor necrosis factor. There is elaborate "cross talk" among the diverse mediators and receptors involved in CQ-induced pruritus. CQ also binds to the mas-related G protein coupled receptors MrgprA3/MrgprX1 present in a small proportion (4-5%) of dorsal root ganglion neurons and skin. The mrgprA3 CQ receptors are coupled to PLC-β3 and a chloride channel to initiate skin itch action potentials in C nerve fibers. Mrgpra3/X1 couples to TRPA1 for calcium influx into neuronal cells at noncutaneous sites. Central CQ itch occurs via gastrin-related peptide (GRP) and its receptor (GRPR) in the dorsal spinothalamic tracts, as well as glutamic mediated GRP projection to parabrachial nucleus. The possibility of chronic itch therapy based on personalized medicine, genetics, and transcriptomics or the use of itch "polypill/polycream" are discussed.

Itch and psyche: psychiatric aspects of pruritus

Itch, also referred to as pruritus, is an unpleasant cutaneous sensation provoking the desire to scratch. It is often an uncomfortable, subjective sensation responsible for decreased quality of life in a variety of psychodermatological conditions. Comorbid psychiatric conditions, including depression and anxiety, are frequently associated with itch and scratch cycle. The reciprocal and intricate relationship between the psyche and itch has been widely studied. The neurobiology of itch involves the complexity of specific mediators, itch-related neuronal pathways, and central processing of itch. The connection between itch and the psyche can be grouped under three headings: pruritic diseases with psychosocial sequelae, pruritic diseases aggravated by psychosocial factors, and psychiatric disorders causing pruritus. Itch and pain modulation go together in most circumstances and involve various substances including histamine, interleukins, protease-activated receptors, transient receptor potential receptors, opioids, and cannabinoids. The close interaction between keratinocytes and nerve endings modulating pain and itch also play a major role. Management of itch associated with its psychosomatic components is directed at an underlying cause and adopting a holistic approach to address not only dermatologic and somatosensory aspects, but also the cognitive, emotional, and psychosocial components. An integrated multidisciplinary team consisting of a dermatologist, psychiatrist, psychologist, and social worker is vital in addressing the multifaceted aspects of pruritus.

Investigating endogenous µ-opioid receptors in human keratinocytes as pharmacological targets using novel fluorescent ligand

Opioids in skin function during stress response, regeneration, ageing and, particularly in regulating sensation. In chronic pruritus, topical treatment with Naltrexone changes μ-opioid receptor (μ-OR) localization to relieve itch. The molecular mechanisms behind the effects of Naltrexone on μ-OR function in reduction of itching behavior has not been studied. There is an immediate need to understand the endogenous complexity of μ-OR dynamics in normal and pathological skin conditions. Here we evaluate real-time behavior of μ-OR-Endomorphine complexes in the presence of agonist and antagonists. The μ-OR ligand Endomorphine-1 (EM) was conjugated to the fluorescent dye Tetramethylrhodamine (TAMRA) to investigate the effects of agonist and antagonists in N/TERT-1 keratinocytes. The cellular localization of the EM-TAMRA was followed through time resolved confocal microscopy and population analysis was performed by flow cytometry. The in vitro analyses demonstrate fast internalization and trafficking of the endogenous EM-TAMRA-μ-OR interactions in a qualitative manner. Competition with Endomorphine-1, Naltrexone and CTOP show both canonical and non-canonical effects in basal and differentiated keratinocytes. Acute and chronic treatment with Naltrexone and Endomorphine-1 increases EM-TAMRA binding to skin cells. Although Naltrexone is clinically effective in relieving itch, the mechanisms behind re-distribution of μ-ORs during clinical treatments are not known. Our study has given insight into cellular mechanisms of μ-OR ligand-receptor interactions after opioid agonist and antagonist treatments in vitro. These findings potentially offer opportunities in using novel treatment strategies for skin and peripheral sensory disorders.

Notalgia Paresthetica: A Novel Approach to Treatment with Cryolipolysis

Notalgia paresthetica, a neurosensory syndrome that typically occurs on the upper back, has multiple clinical symptoms with variable degrees of expression in each individual afflicted with the condition. The involved site is usually hyperpigmented and is associated with burning, coldness, hypoesthesia, increased pain, pruritus and/or tingling. In the affected area, the number of nerve fibers may be increased and the cutaneous sensory nerves are altered secondary to localized impingement, central injury, or both. Although multiple therapeutic approaches for notalgia paresthetica have been described, none specifically address the essential pathogenesis of the condition—the altered cutaneous nerves. Cryolipolysis is a well-tolerated nonsurgical technique to reduce the subcutaneous fat layer. Selective apoptosis of adipocytes occurs since the lipid-rich fat cells are more susceptible to cold injury than the surrounding water-rich cells. Not only a marked decrease in pain sensitivity but also a sustained reduction in the density of myelinated and unmyelinated cutaneous nerves has been observed in cryolipolysis-treated skin. Therefore, cryolipolysis is a logical approach to the treatment of notalgia paresthetica. One or more cryolipolysis treatments may be necessary for complete or partial resolution of the individual’s notalgia paresthetica-related cutaneous symptoms. In conclusion, evaluation of cryolipolysis as a noninvasive treatment of patients with notalgia paresthetica is warranted.

Naltrexone Inhibits IL-6 and TNFα Production in Human Immune Cell Subsets following Stimulation with Ligands for Intracellular Toll-Like Receptors

The opioid antagonist naltrexone hydrochloride has been suggested to be a potential therapy at low dosage for multiple inflammatory conditions and cancers. Little is known about the immune-modulating effects of naltrexone, but an effect on the activity of toll-like receptor 4 (TLR4) has been reported. We analyzed the effects of naltrexone hydrochloride on IL-6 secretion by peripheral blood mononuclear cells (PBMC) in vitro following stimulation with ligands for TLR4 and for the intracellular receptors TLR7, TLR8, and TLR9. Naltrexone did not affect cell viability or induce apoptosis of PBMC. Intracellular staining demonstrated that naltrexone inhibited production of IL-6 and TNFα by monocyte and plasmacytoid dendritic cell subsets within the PBMC population following treatment with ligands for TLR7/8 and TLR9, respectively. No effect of cytokine production by PBMC following stimulation of TLR4 was observed. Additionally, naltrexone inhibited IL-6 production in isolated monocytes and B cells after TLR7/8 and TLR9 stimulation, respectively, but no effect on IL-6 production in isolated monocytes after TLR4 stimulation was observed. These findings indicate that naltrexone has the potential to modulate the secretion of inflammatory cytokines in response to intracellular TLR activity, supporting the hypothesis that it may have potential for use as an immunomodulator.

Adjunctive Management of Itch in Atopic Dermatitis

Itch, or pruritus, is a hallmark feature of atopic dermatitis (AD). The impact of AD-related pruritus can range from mildly distressing or distracting to completely disabling. Traditionally, management of itch in AD patients has focused on restoring the altered skin barrier with topical emollients and/or reducing inflammation. A growing emphasis has been placed on directly targeting the neural transmission pathways that mediate itch signaling. Off-label use of neuromodulatory agents has helped reduce this aggravating symptom in atopic patients. This article reviews the current literature on the use of neuromodulatory agents and nonpharmacologic alternative therapies used to treat AD-related pruritus.

Psychocutaneous disease: Pharmacotherapy and psychotherapy

Building a strong therapeutic alliance with the patient is of utmost importance in the management of psychocutaneous disease. Optimal management of psychocutaneous disease includes both pharmacotherapy and psychotherapy. This article reviews psychotropic medications currently used for psychocutaneous disease, including antidepressants, antipsychotics, mood stabilizers, and anxiolytics, with a discussion of relevant dosing regimens and adverse effects. Pruritus management is addressed. In addition, basic and complex forms of psychotherapy, such as cognitive-behavioral therapy and habit-reversal training, are described.

Pharmacological interventions for pruritus in adult palliative care patients

BACKGROUND

This is an update of the original Cochrane review published in 2013 (Issue 6). Pruritus occurs in patients with disparate underlying diseases and is caused by different pathologic mechanisms. In palliative care patients, pruritus is not the most prevalent but is one of the most puzzling symptoms. It can cause considerable discomfort and affects patients' quality of life.

OBJECTIVES

To assess the effects of different pharmacological treatments for preventing or treating pruritus in adult palliative care patients.

SEARCH METHODS

For this update, we searched CENTRAL (the Cochrane Library), and MEDLINE (OVID) up to 9 June 2016 and Embase (OVID) up to 7 June 2016. In addition, we searched trial registries and checked the reference lists of all relevant studies, key textbooks, reviews and websites, and we contacted investigators and specialists in pruritus and palliative care regarding unpublished data.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) assessing the effects of different pharmacological treatments, compared with a placebo, no treatment, or an alternative treatment, for preventing or treating pruritus in palliative care patients.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the identified titles and abstracts, performed data extraction and assessed the risk of bias and methodological quality. We summarised the results descriptively and quantitatively (meta-analyses) according to the different pharmacological interventions and the diseases associated with pruritus. We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created 10 'Summary of findings' tables.

MAIN RESULTS

In total, we included 50 studies and 1916 participants in the review. We added 10 studies with 627 participants for this update. Altogether, we included 39 different treatments for pruritus in four different patient groups.The overall risk of bias profile was heterogeneous and ranged from high to low risk. However, 48 studies (96%) had a high risk of bias due to low sample size (i.e. fewer than 50 participants per treatment arm). Using GRADE criteria, we downgraded our judgement on the quality of evidence to moderate in seven and to low in three comparisons for our primary outcome (pruritus), mainly due to imprecision and risk of bias.In palliative care participants with pruritus of different nature, the treatment with the drug paroxetine, a selective serotonin reuptake inhibitor, reduced pruritus by 0.78 points (numerical analogue scale from 0 to 10; 95% confidence interval (CI) -1.19 to -0.37; one RCT, N = 48, quality of evidence: moderate) compared to placebo.For participants suffering from uraemic pruritus (UP), gabapentin was more effective than placebo (visual analogue scale (VAS): 0 to 10), mean difference (MD) -5.91, 95% CI -6.87 to -4.96; two RCTs, N = 118, quality of evidence: moderate). The κ-opioid receptor agonist nalfurafine showed amelioration of UP (VAS 0 to 10, MD -0.95, 95% CI -1.32 to -0.58; three RCTs, N = 422, quality of evidence: moderate) and only few adverse events. Moreover, cromolyn sodium relieved UP participants from pruritus by 2.94 points on the VAS (0 to 10) (95% CI -4.04 to -1.83; two RCTs, N = 100, quality of evidence: moderate) compared to placebo.In participants with cholestatic pruritus (CP), data favoured rifampin (VAS: 0 to 100, MD -24.64, 95% CI -31.08 to -18.21; two RCTs, N = 42, quality of evidence: low) and flumecinol (RR > 1 favours treatment group; RR 1.89, 95% CI 1.05 to 3.39; two RCTs, N = 69, quality of evidence: low) and showed a low incidence of adverse events in comparison with placebo. The opioid antagonist naltrexone reduced pruritus for participants with CP (VAS: 0 to 10, MD -2.26, 95% CI -3.19 to -1.33; two RCTs, N = 52, quality of evidence: moderate) compared to placebo. However, effects in participants with UP were inconclusive (percentage difference -12.30%, 95% CI -25.82% to 1.22%, one RCT, N = 32). Furthermore, large doses of opioid antagonists (e.g. naltrexone) could be inappropriate in palliative care patients because of the risk of reducing analgesia.For participants with HIV-associated pruritus, it is uncertain whether drug treatment with hydroxyzine hydrochloride, pentoxifylline, triamcinolone or indomethacin reduces pruritus because the evidence was of very low quality (e.g. small sample size, lack of blinding).

AUTHORS' CONCLUSIONS

Different interventions tended to be effective for CP and UP. However, therapies for patients with malignancies are still lacking. Due to the small sample sizes in most meta-analyses and the heterogeneous methodological quality of the included trials, the results should be interpreted cautiously in terms of generalisability.

Are itch and scratching the nausea and vomiting of skin?

The physiologic similarities between itch and nausea may not be evident initially, but they share the role of repelling irritants and toxins from the body by inducting scratching and vomiting, respectively. In addition, itch and nausea frequently occur together in certain conditions such as uraemia. Here we show that the mechanisms underlying itch and nausea overlap and that advances in either field may influence the identification of novel drug targets, particularly for itch.

Scoping systematic review of treatments for eczema

Background

Eczema is a very common chronic inflammatory skin condition.

Objectives

To update the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) systematic review of treatments for atopic eczema, published in 2000, and to inform health-care professionals, commissioners and patients about key treatment developments and research gaps.

Data sources

Electronic databases including MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Skin Group Specialised Register, Latin American and Caribbean Health Sciences Literature (LILACS), Allied and Complementary Medicine Database (AMED) and Cumulative Index to Nursing and Allied Health Literature (CINAHL) were searched from the end of 2000 to 31 August 2013. Retrieved articles were used to identify further randomised controlled trials (RCTs).

Review methods

Studies were filtered according to inclusion criteria and agreed by consensus in cases of uncertainty. Abstracts were excluded and non-English-language papers were screened by international colleagues and data were extracted. Only RCTs of treatments for eczema were included, as other forms of evidence are associated with higher risks of bias. Inclusion criteria for studies included availability of data relevant to the therapeutic management of eczema; mention of randomisation; comparison of two or more treatments; and prospective data collection. Participants of all ages were included. Eczema diagnosis was determined by a clinician or according to published diagnostic criteria. The risk of bias was assessed using the Cochrane Collaboration risk-of-bias tool. We used a standardised approach to summarising the data and the assessment of risk of bias and we made a clear distinction between what the studies found and our own interpretation of study findings.

Results

Of 7198 references screened, 287 new trials were identified spanning 92 treatments. Trial reporting was generally poor (randomisation method: 2% high, 36% low, 62% unclear risk of bias; allocation concealment: 3% high, 15% low, 82% unclear risk of bias; blinding of the intervention: 15% high, 28% low, 57% unclear risk of bias). Only 22 (8%) trials were considered to be at low risk of bias for all three criteria. There was reasonable evidence of benefit for the topical medications tacrolimus, pimecrolimus and various corticosteroids (with tacrolimus superior to pimecrolimus and corticosteroids) for both treatment and flare prevention; oral ciclosporin; oral azathioprine; narrow band ultraviolet B (UVB) light; Atopiclair™ and education. There was reasonable evidence to suggest no clinically useful benefit for twice-daily compared with once-daily topical corticosteroids; corticosteroids containing antibiotics for non-infected eczema; probiotics; evening primrose and borage oil; ion-exchange water softeners; protease inhibitor SRD441 (Serentis Ltd); furfuryl palmitate in emollient; cipamfylline cream; andMycobacterium vaccaevaccine. Additional research evidence is needed for emollients, bath additives, antibacterials, specialist clothing and complementary and alternative therapies. There was no RCT evidence for topical corticosteroid dilution, impregnated bandages, soap avoidance, bathing frequency or allergy testing.

Limitations

The large scope of the review coupled with the heterogeneity of outcomes precluded formal meta-analyses. Our conclusions are still limited by a profusion of small, poorly reported studies.

Conclusions

Although the evidence base of RCTs has increased considerably since the last NIHR HTA systematic review, the field is still severely hampered by poor design and reporting problems including failure to register trials and declare primary outcomes, small sample size, short follow-up duration and poor reporting of risk of bias. Key areas for further research identified by the review include the optimum use of emollients, bathing frequency, wash products, allergy testing and antiseptic treatments. Perhaps the greatest benefit identified is the use of twice weekly anti-inflammatory treatment to maintain disease remission. More studies need to be conducted in a primary care setting where most people with eczema are seen in the UK. Future studies need to use the same core set of outcomes that capture patient symptoms, clinical signs, quality of life and the chronic nature of the disease.

Funding

The National Institute for Health Research Programme Grants for Applied Research programme.

Methylnaltrexone: its pharmacological effects alone and effects on morphine in healthy volunteers

RATIONALE

Methylnaltrexone bromide (MTNX) is a peripherally acting mu-opioid receptor antagonist, prescribed for the treatment of opioid-induced constipation in patients with advanced illness who are receiving palliative care. Studies have used this drug to determine if other opioid-induced effects besides constipation are altered by MTNX in humans and have suggested, based on their results, that these other effects are altered by peripheral opioid actions.

OBJECTIVE

The primary objective of this report is to present results that provide indirect evidence that MTNX has centrally mediated effects, albeit slight, and secondarily to describe the effects of MTNX on psychopharmacological effects of morphine.

METHODS

In a crossover, randomized, placebo-controlled, double-blind study, 29 healthy volunteers received 0.45 mg/kg MTNX or saline subcutaneously, followed by saline intravenously. In three other conditions, 0.143 mg/kg of morphine sulfate administered intravenously was preceded by subcutaneous administration of 0, 0.225, or 0.45 mg/kg MTNX. Before and after drug administration, subjective and physiological measures, including pupil diameter, were assessed.

RESULTS

Two separate analyses confirmed that 0.45 mg/kg MTNX alone induced a slight degree of miosis, a centrally mediated opioid agonist effect. This dose had minimal subjective effects. MTNX at either or both the 0.225 and 0.45 mg/kg dose reduced some subjective effects of morphine without altering miosis.

CONCLUSIONS

We present indirect evidence that MTNX crosses the blood-brain barrier in humans. Therefore, whether the reductions in subjective effects of morphine by MTNX that were observed in past studies and in this study can be attributed to peripheral mechanisms is open to question.

Ex vivo studies for the passive transdermal delivery of low-dose naltrexone from a cream; detection of naltrexone and its active metabolite, 6β-naltrexol, using a novel LC Q-ToF MS assay

Naltrexone (NTX) is a long-acting opiate antagonist. Low-dose naltrexone (LDN) therapy has shown promising results in the treatment of several autoimmune disorders. Our aim was to formulate NTX into a cream for the delivery of LDN and develop an analytical technique for the quantification of NTX and its active metabolite 6-β-naltrexol (NTXol) during transdermal diffusion cell permeation studies. A 1% w/w NTX cream was formulated and drug permeation was examined over 24 h using static Franz diffusion cells mounted with pig skin. A Liquid Chromatography Quadrupole-Time of Flight Mass Spectrometry (LC-MS Q-ToF) method was developed for the detection of NTX and NTXol in the receptor solution, skin membrane and residual cream on the donor chamber after completion of the diffusion studies. The cream formulation exhibited steady state release of NTX over 24 h after an initial lag time of 2.74 h. The bioconversion of NTX to NTXol in the skin membrane was 1.1%. It was concluded that the cream may be an effective formulation for the sustained transdermal delivery of LDN. The novel LC Q-ToF MS method allowed the accurate measurement of NTX and NTXol levels across the diffusion cell assemblies and the quantification of NTX metabolism in the skin.