Randomised crossover trial of naltrexone in uraemic pruritus

Chronic kidney disease-associated pruritus: what is known and its application in children

Chronic kidney disease-associated pruritus (CKD-aP) or uremic pruritus (UP) is a frequent symptom in patients with kidney failure receiving kidney replacement therapy. Severe chronic kidney disease-associated pruritus correlates with poor outcome in patients on dialysis. It is multifactorial in etiology and has a significant impact on quality of life. There is, however, limited data for children. This review summarizes current epidemiology, clinical characteristics, pruritus scoring systems, and available therapeutic options for pruritus in patients with chronic kidney disease and those receiving dialysis. Optimal care requires proper awareness of the severity of symptoms, the impact on quality of life, and the possible long-term outcomes. Optimizing dialysis prescription and correcting electrolyte abnormalities are important treatment targets. A wide range of therapeutic options is also available although none are well-studied in children. An earlier recognition of this debilitating symptom in children and treatment is imperative. A higher resolution version of the Graphical abstract is available as Supplementary information.

Pathogenesis and Treatment of Pruritus Associated with Chronic Kidney Disease and Cholestasis

Itching is an unpleasant sensation that provokes the desire to scratch. In general, itching is caused by dermatologic diseases, but it can also be caused by systemic diseases. Since itching hampers patients' quality of life, it is important to understand the appropriate treatment and pathophysiology of pruritus caused by systemic diseases to improve the quality of life. Mechanisms are being studied through animal or human studies, and various treatments are being tested through clinical trials. We report current trends of two major systemic diseases: chronic kidney disease and cholestatic liver disease. This review summarizes the causes and pathophysiology of systemic diseases with pruritus and appropriate treatments. This article will contribute to patients' quality of life. Further research will help understand the mechanisms and develop new strategies in the future.

Perception of Spanish nephrologists on an old unsolved problem: Pruritus associated with chronic kidney disease (CKD-aP)

INTRODUCTION

Pruritus associated with chronic kidney disease is defined as the sensation of itching, in people with chronic kidney disease, in a one area or all over the body that causes the need to scratch, after having ruled out other dermatological or systemic causes. It is an old and known problem whose prevalence has been able to decrease with the improvement of dialytic techniques but which still persists and is underdiagnosed.

OBJECTIVES

The objective of this study was to analyse the current perception of nephrologists about this problem that influences the quality of life of people with chronic kidney disease through a survey.

RESULTS

135 nephrologists, most of them engaged in haemodialysis, participated. 86% considered that pruritus associated with chronic kidney disease is still a problem today that affects the quality of life. Most nephrologists believe that the main pathophysiological cause is uremic toxins (60%) and only 16% believe that it is due to the dysregulation of the opioid system/endorphins-dynorphins. Only 16% comment that the prevalence of pruritus in their centre is greater than 20%. 40% believe that the diagnosis is made because it is manifested by the patient and only 27% because it is asked by the doctor. Moreover, it is not usual to use scales to measure it or the codification in the medical records. The main treatment used is antihistamines (96%), followed by moisturizers/anaesthetics (93%) and modification of the dialysis regimen (70%).

CONCLUSIONS

Pruritus associated with chronic kidney disease is still a current problem, it is underdiagnosed, not codified and with a lack of indicated, effective and safe treatments. Nephrologists do not know its real prevalence and the different pathophysiological mechanisms involved in its development. Many therapeutic options are used with very variable results, ignoring their efficacy and applicability at the present time. The new emerging kappa-opioid-receptor agonist agents offer us an opportunity to reevaluate this age-old problem and improve the quality of life for our patients with chronic kidney disease.

Uremic pruritus: pathophysiology, clinical presentation, and treatments

Uremic pruritus is one of the most common and bothersome symptoms in patients with end-stage renal disease. Most patients with uremic pruritus experience a prolonged and relapsing course and significant impairments of quality of life. The pathophysiology of uremic pruritus is not completely understood. A complex interplay among cutaneous biology and the nervous and immune systems has been implicated, with the involvement of various inflammatory mediators, neurotransmitters, and opioids. Uremic pruritus treatment outcomes are often unsatisfactory. Clinical trials have mostly been small in scale and have reported inconsistent results. Recent evidence shows that gabapentinoids, nalfurafine, and difelikefalin are effective for relieving uremic pruritus in hemodialysis patients. This review provides an overview of the epidemiology and proposed mechanisms of uremic pruritus, then highlights the manifestations of and clinical approach to uremic pruritus. Current evidence regarding treatment options, including topical treatments, treatment of underlying disease, phototherapy, and systemic treatments, is also outlined. With a better understanding of uremic pruritus, more therapeutic options can be expected in the near future.

Nouvelles thérapies dans la prise en charge du patient avec maladie rénale chronique souffrant de prurit : une revue de la littérature New therapies in the management of chronic kidney disease associated pruritus

Chronic Kidney Disease associated Pruritus (CKD-aP) is a well-established and frequent complication observed in patient with CKD, especially in dialysis patients. However, the management of CKD-aP remains a challenge as the pathophysiology and research studies are too small. Finally, there are a few proposed treatment options with significant clinical benefits. This general review will summarize all the available treatments for the CKD-aP and will highlight the clinical efficacy and limits of the current drugs. Notably, we will focus on the implication of the opioid receptor in the pathophysiology of the CKD-aP and the recently Kappa opioid receptor agonist. © 2022 Published by Elsevier Masson SAS on behalf of Société francophone de néphrologie, dialyse et transplantation.

Alleviating symptoms in patients undergoing long-term hemodialysis: a focus on chronic kidney disease-associated pruritus

Since the breakthrough of kidney replacement therapy, increases in life expectancy for patients with end-stage kidney disease have been limited. However, patients have become increasingly vocal that, although mortality and life expectancy matter to them, the quality of their life, and particularly the relief of symptoms associated with their treatment, are in many cases more important. The majority of dialysis-associated symptoms and adverse effects do not currently have any approved treatments in this patient population, with the few treatments that are available used off-label, frequently without proven efficacy, yet still potentially adding further adverse effects to patients' current symptom burden. This article will illustrate how understanding the pathophysiology of a single, particularly burdensome symptom of dialysis (chronic kidney disease-associated pruritus) resulted in the design, development and regulatory approval of a treatment for that symptom. The pathway described here can be applied to other symptoms associated with dialysis, meaning that if we cannot add years to patients' lives, we can at least add life to their remaining years.

Uremic Pruritus: From Diagnosis to Treatment

Uremic pruritus, or chronic kidney disease-associated pruritus, is common, bothersome, and sometimes debilitating in patients with chronic kidney disease or end-stage renal disease. Due to its variable clinical manifestations, the diagnosis of uremic pruritus requires exquisite evaluation. Excluding itch resulting from other dermatological causes as well as other systemic conditions is essential for a proper diagnosis. The pathophysiology of uremic pruritus remains uncertain. Hypotheses including toxin deposition, immune system dysregulation, peripheral neuropathy, and opioid imbalance are supposed. This review summarizes the way to accurately diagnose uremic pruritus and describes the latest treatment options.

Transport of Maternally Administered Pharmaceutical Agents Across the Placental Barrier In Vitro

To understand the transport of pharmaceutical agents and their effects on developing fetus, we have created a placental microsystem that mimics structural phenotypes and physiological characteristic of a placental barrier. We have shown the formation of a continuous network of epithelial adherens junctions and endothelial cell-cell junctions confirming the integrity of the placental barrier. More importantly, the formation of elongated microvilli under dynamic flow condition is demonstrated. Fluid shear stress acts as a mechanical cue triggering the microvilli formation. Pharmaceutical agents were administered to the maternal channel, and the concentration of pharmaceutical agents in fetal channel for coculture and control models were evaluated. In fetal channel, the coculture model exhibited about 2.5 and 2.2% of the maternal initial concentration for naltrexone and 6β-naltrexol, respectively. In acellular model, fetal channel showed about 10.5 and 10.3% of the maternal initial concentration for naltrexone and 6β-naltrexol, respectively. Gene expressions of epithelial cells after direct administration of naltrexone and 6β-naltrexol to the maternal channel and endothelial cells after exposure due to transport through placental barrier are also reported.

Unravelling the pathophysiology of chronic kidney disease-associated pruritus

For decades, itch related to chronic kidney disease (CKDaP) has been a clinical problem, but the aetiology and pathophysiology of CKDaP are still not yet fully understood—currently the underlying pathophysiological mechanisms are thought to be multifactorial. As new therapeutic targets have recently been identified and clinical trials have shown promising results, our current understanding of the interrelationships has expanded significantly. Here we review the pathophysiology and recent findings on modulation and sensitization of itch contributing to the development of CKDaP, covering hypothesis regarding immune system dysfunction, metabolic changes, uremic toxin deposition, peripheral neuropathy and imbalances in the endogenous opioid system.

Palliative care for children and young people with stage 5 chronic kidney disease

Death from stage 5 chronic kidney disease (CKD 5) in childhood or adolescence is rare, but something that all paediatric renal physicians and most paediatricians will encounter. In this paper, we present the literature on three key areas of palliative care practice essential to good clinical management: shared decision-making, advance care planning, and symptom management, with particular reference to CKD 5 where kidney transplant is not an option and where a decision has been made to withdraw or withhold dialysis. Some areas of care, particularly with regard to symptom management, have not been well-studied in children and young people (CYP) with CKD 5 and recommendations with regard to drug choice and dose modification are based on adult literature, known pharmacokinetics, and clinical experience.

Pruritus in dialysis patients. Review and new perspectives

Uremic pruritus (UP) is one of the most uncomfortable symptoms for patients in dialysis. UP has a great impact on dialysis patients' quality of life and has a great prevalence between those (28-70%). Physiopathology of UP is unknown and usually is unnoticed for most nephrologists (in more than 65% of centers is underdiagnosed). This lack of awareness drives to the unsuccessful treatment of this symptom. Moreover, the fact that most studies have been carried out on small populations and the difficulty assessing UP complicates a correct therapeutical approach. For this reason, we have designed treatment algorithms based on the efficacy of the drugs but also its safeness to avoid adverse effects.

Clinical management of chronic kidney disease-associated pruritus: current treatment options and future approaches

Chronic kidney disease (CKD)-associated pruritus (CKD-aP) is an underdiagnosed yet severely distressing condition that impacts 60% of patients on dialysis and many nondialysis patients with Stages 3–5 CKD. However, despite its high prevalence, there are currently limited treatment options available for these patients and a lack of treatment guidelines for clinicians. In this manuscript, we reviewed the available literature in order to evaluate the current management and treatment options for CKD-aP, including dialysis management, topical treatments, gabapentinoids, opioids and alternative medicine. We also review the available data on CKD-aP treatments in development and propose new guidelines for managing patients with CKD-aP.

Do you feel itchy? A guide towards diagnosis and measurement of chronic kidney disease-associated pruritus in dialysis patients

Chronic kidney disease-associated pruritus (CKD-aP) is a potentially distressing condition that affects a significant proportion of patients with end-stage kidney disease undergoing dialysis. CKD-aP may lead to worsening of patients' physical and mental health-related quality of life (HRQoL) and has also been linked with worse clinical outcomes, including increased mortality. Despite these detrimental effects, evidence from real-world studies shows that CKD-aP still remains overlooked by nephrologists and underreported by patients in clinical practice. Itch is subjective and therefore its diagnosis is often dependent on patients reporting this symptom. There is an opportunity to reduce the burden of CKD-aP on dialysis patients by increasing awareness about this condition and the availability of effective treatments. It is particularly important that nephrologists and other healthcare providers routinely ask their patients if they are experiencing itch. The differential diagnosis of CKD-aP requires a step-by-step identification and exclusion of possible alternative or concomitant causes of itch. Several simple validated self-reported assessment scales are available to evaluate the presence and severity of itch in a time-efficient manner, making them suitable for use in everyday clinical practice. The impact of CKD-aP on haemodialysis patients' HRQoL should also be assessed on a regular basis. This review provides a comprehensive overview of the differential diagnosis of CKD-aP and the diagnostic tools that are available to identify itch and quantify its severity and impact on patient HRQoL. A suggested algorithm to guide the screening, diagnosis and assessment of CKD-aP among dialysis patients in real-world practice is provided.

Chronic Intractable Pruritus in Chronic Kidney Disease Patients: Prevalence, Impact, and Management Challenges - A Narrative Review

Chronic kidney disease (CKD) is recognized as a leading public health problem and causes numerous health complications. One of the most common and burdensome dermatological symptoms affecting patients undergoing dialysis is CKD-associated pruritus (CKD-aP). This condition not only has a negative impact on sleep, mood, daily activities, and quality of life but also increases the mortality risk of hemodialyzed patients. Despite that, this condition is greatly underestimated in clinical practice. Due to the complex and still not fully understood etiopathogenesis of CKD-aP, the choice of an effective therapy remains a challenge for clinicians. Most common therapeutic algorithms use topical treatment, phototherapy, and various systemic approaches. This review aimed to summarize most recent theories about the pathogenesis, clinical features, and treatment of CKD-aP.

[Pruritus associated chronic kidney disease]

Pruritus associated with chronic kidney disease is a frequent and disabling symptom in patients with severe chronic kidney disease treated by dialysis. It is associated with a poor quality of life, an increased risk of comorbidities and even mortality. Nevertheless, its prevalence is underestimated by nephrologists. The pathophysiology of pruritus associated with chronic kidney disease is not well understood, but several mechanisms seem to contribute to its occurrence: accumulation and skin deposition of uremic toxins, peripheral neuropathy causing an activation of the pruritogenic cowhage pathway, chronic microinflammation, opioid imbalance, and kidney disease-related skin xerosis. Optimization of the treatment of chronic kidney disease treatment, of dialysis parameters, and general skin care measures should always be performed prior to the introduction of systemic therapy targeting one or more of these mechanisms. The available therapeutic trials remain mostly at high risk of bias, with small patient numbers. Gabapentinoids are the molecules recommended as first-line therapy. Peripheral opioid agonists could find a place of choice in the treatment of pruritus associated with chronic kidney disease and will soon be available in France. The low level of evidence for the other molecules does not currently allow us to specify a second-line treatment for this condition.

Itch: Pathogenesis and treatment

Itch pathogenesis is broadly characterized into histaminergic and nonhistaminergic pathways and transmitted via 2 main receptor families: G protein-coupled receptors and transient receptor potential channels. In the skin, itch is primarily transmitted by unmyelinated type C and thinly myelinated type Aδ nerve fibers. Crosstalk between the immune and neural systems modulates itch transmission at the skin, spinal cord, and brain. Among the many known pruritogens, Th2 cytokines, such as interleukin-4, interleukin-13, interleukin-31, and thymic stromal lymphopoietin, are particularly important mediators that signal through shared Janus kinase pathways, representing novel targets for novel itch therapeutics. Emerging evidence has also revealed that the opioidergic system is a potent modulator of itch transmission, with increased μ-opioid activity and decreased κ-opioid activity contributing to itch pathogenesis. Optimal management of itch requires that treatment approaches be tailored to specific etiologic itch subtypes. When the etiology is unknown and patients are given a diagnosis of chronic pruritus of unknown origin, treatment should be guided by the presence of Th2 polarization, often reflected by increased blood eosinophils. In the second article of this 2-part series, we outline our current understanding of itch pathogenesis and discuss available and emerging treatments for itch.

Developmental Considerations for the Use of Naltrexone in Children and Adolescents

Naltrexone (NTX) is a well-tolerated drug with a wide safety margin and mechanism of action that affords use across a wide variety of indications in adults and children. By antagonizing the opioid reward system, NTX can modulate behaviors that involve compulsivity or impulsivity, such as substance use, obesity, and eating disorders. Evidence regarding the disposition and efficacy of NTX is mainly derived from adult studies of substance use disorders and considerable variability exists. Developmental changes, plausible disease-specific alterations and genetic polymorphisms in NTX disposition, and pharmacodynamic pathways should be taken into consideration when optimizing the use of NTX in the pediatric population. This review highlights the current state of the evidence and gaps in knowledge regarding NTX to facilitate evidence-based pharmacotherapy of mental health conditions, for which few pharmacologic options exist.

The Role of Psychiatric, Analgesic, and Antiepileptic Medications in Chronic Pruritus

Chronic pruritus is a complex yet prevalent concern without a gold standard treatment. The mainstay therapy for chronic pruritus includes topical ointments such as corticosteroids, capsaicin, local anesthetics, antihistamines, and immunomodulators. There are many different subtypes of chronic pruritus, and each unique subtype may benefit from specialized treatments. This review article sheds light on the role of psychiatric, analgesic, and antiepileptic medications in chronic pruritus. We believe that further large-scale studies are needed to determine the true effectiveness of these medications in treating chronic pruritus.

Chronic Kidney Disease-Associated Pruritus: A Review

BACKGROUND

Chronic kidney disease-associated pruritus (CKD-aP), also known as uraemic pruritus, is a disabling symptom for patients and a challenging condition for clinicians. Despite being common amongst end-stage kidney disease (ESKD) patients, it remains underestimated and underdiagnosed. The exact pathogenesis remains largely elusive, which hampers the synthesis of a definite treatment approach.

SUMMARY

Chronic pruritus (lasting 6 weeks or more in duration) is a common and potentially disabling symptom in patients with advanced CKD. A unified hypothesis of pathogenesis has not yet been concluded. Studies have shown changes in the immunochemical milieu of the skin in patients with CKD-aP with several inciting stimuli identified. However, other unrecognized factors are likely to be involved. This article will review the current observations and understanding of the postulated pathogenesis of CKD-aP, as well as the evidence for current management strategies. Key Messages: CKD-aP is a common and troubling symptom amongst ESKD patients that is associated with decreased quality of life and poor prognosis. Its exact pathogenesis, at the time of writing, is not well-understood. A stepwise approach is recommended for management. Systematic reviews show the largest body of evidence was found for the effectiveness of gabapentin. Comparison is needed between newly emerging pharmacological agents such as kappa-opioid receptor agonists and more established agents, such as the gabapentinoids. Finally, renal transplantation should be considered in severe and refractory cases who are suitable transplant candidates as it has shown an excellent outcome in most cases.

Systemic causes of non-dermatologic chronic pruritus in the pediatric population and their management: An unexplored area

Chronic pruritus associated with systemic diseases in the pediatric population has been infrequently addressed in the literature. This review focuses on chronic pruritus presenting without cutaneous manifestations. Common systemic etiologies include diseases with hepatic, renal, and hematologic origins. This encompasses several congenital liver disorders, end-stage renal disease (ESRD), and lymphoproliferative disorders such as Hodgkin's lymphoma. In this paper, an expert panel describes the clinical characteristics, pathophysiology, and therapeutic treatment ladders for chronic pruritus associated with the aforementioned systemic etiologies. Novel therapies are also reviewed. Our aim is to shed light on this unexplored area of pediatric dermatology and instigate further research.

Pruritus in dialysis patients. Review and new perspectives

Uremic pruritus (UP) is one of the most uncomfortable symptoms for patients in dialysis. UP has a great impact on dialysis patients' quality of life and has a great prevalence between those (28-70%). Physiopathology of UP is unknown and usually is unnoticed for most nephrologists (in more than 65% of centers is underdiagnosed). This lack of awareness drives to the unsuccessful treatment of this symptom. Moreover, the fact that most studies have been carried out on small populations and the difficulty assessing UP complicates a correct therapeutical approach. For this reason, we have designed treatment algorithms based on the efficacy of the drugs but also its safeness to avoid adverse effects.

Central opioid receptors mediate morphine-induced itch and chronic itch via disinhibition

Opioids such as morphine are mainstay treatments for clinical pain conditions. Itch is a common side effect of opioids, particularly as a result of epidural or intrathecal administration. Recent progress has advanced our understanding of itch circuits in the spinal cord. However, the mechanisms underlying opioid-induced itch are not fully understood, although an interaction between µ-opioid receptor (MOR) and gastrin-releasing peptide receptor (GRPR) in spinal GRPR-expressing neurons has been implicated. In this study we investigated the cellular mechanisms of intrathecal opioid-induced itch by conditional deletion of MOR-encoding Oprm1 in distinct populations of interneurons and sensory neurons. We found that intrathecal injection of the MOR agonists morphine or DAMGO elicited dose-dependent scratching as well as licking and biting, but this pruritus was totally abolished in mice with a specific Oprm1 deletion in Vgat+ neurons [Oprm1-Vgat (Slc32a1)]. Loss of MOR in somatostatin+ interneurons and TRPV1+ sensory neurons did not affect morphine-induced itch but impaired morphine-induced antinociception. In situ hybridization revealed Oprm1 expression in 30% of inhibitory and 20% of excitatory interneurons in the spinal dorsal horn. Whole-cell recordings from spinal cord slices showed that DAMGO induced outward currents in 9 of 19 Vgat+ interneurons examined. Morphine also inhibited action potentials in Vgat+ interneurons. Furthermore, morphine suppressed evoked inhibitory postsynaptic currents in postsynaptic Vgat- excitatory neurons, suggesting a mechanism of disinhibition by MOR agonists. Notably, morphine-elicited itch was suppressed by intrathecal administration of NPY and abolished by spinal ablation of GRPR+ neurons with intrathecal injection of bombesin-saporin, whereas intrathecal GRP-induced itch response remained intact in mice lacking Oprm1-Vgat. Intrathecal bombesin-saporin treatment reduced the number of GRPR+ neurons by 97% in the lumber spinal cord and 91% in the cervical spinal cord, without changing the number of Oprm1+ neurons. Additionally, chronic itch from DNFB-induced allergic contact dermatitis was decreased by Oprm1-Vgat deletion. Finally, naloxone, but not peripherally restricted naloxone methiodide, inhibited chronic itch in the DNFB model and the CTCL model, indicating a contribution of central MOR signalling to chronic itch. Our findings demonstrate that intrathecal morphine elicits itch via acting on MOR on spinal inhibitory interneurons, leading to disinhibition of the spinal itch circuit. Our data also provide mechanistic insights into the current treatment of chronic itch with opioid receptor antagonist such as naloxone.

Pharmacological Characterization of a Novel Mouse Model of Cholestatic Pruritus

Patients with cholestatic liver diseases, such as primary biliary cirrhosis, usually suffer from pruritus. However, the pathogenesis of cholestatic pruritus is unclear, and there is no current effective treatment for it. In order to find a treatment for the condition, an appropriate mouse model should be developed. Therefore, here, we established a surgically-induced mouse model of cholestatic pruritus. The bile duct was ligated in order to block bile secretion from the anterior, right, and left lobes, with the exception of the caudate lobe. Serum levels of total bile acid increased after bile duct ligation (BDL). The spontaneous hind paw scratching was also increased in BDL mice. Spontaneous scratching was reduced in BDL mice by naloxone (µ-opioid receptor antagonist), U-50,488H (κ-opioid receptor agonist), and clonidine (α2-adrenoceptor agonist). Azelastine (H₁ receptor antagonist with membrane-stabilizing activity) slightly reduced scratching. However, terfenadine (H₁ receptor antagonist), methysergide (serotonin (5-HT)₂ receptor antagonist), ondansetron (5-HT₃ receptor antagonist), proteinase-activated receptor 2-neutralizing antibody, fluvoxamine (selective serotonin reuptake inhibitor), milnacipran (serotonin-noradrenalin reuptake inhibitor), and cyproheptadine (H₁ and 5-HT₂ receptor antagonist) did not affect scratching. These results suggested that partial obstruction of bile secretion in mice induced anti-histamine-resistant itching and that central opioid system is involved in cholestatic itching.

Effectiveness and safety of different medicines for Uremia pruritus: A protocol for systematic review and network meta analysis

INTRODUCTION

A large number of patients will experience pruritus after uremia. Medicine is the preferred treatment for many doctors, but the effectiveness and safety of different medicines for uremia pruritus has not yet been comprehensively compared, based on network meta-analysis.

METHODS AND ANALYSIS

According to the retrieval strategy, two team members independently searched the literature in 7 databases, and imported the retrieval results into the EndNote Software AQ8 (V.X9). After deleting repeated articles, they read the abstract and the full text, selected the articles that met the inclusion criteria and extracted valid information. The main results were visual analogue scale (VAS) and the secondary results were verbal rating scale (VRS), Dirk R Kuypers score, and adverse event incidence. The methodological quality evaluation was conducted from 7 aspects, according to The Cochrane Collaborative Tool, Stata Statistical Software (Version 14.0, Stata Corporation, College Station, TX) was used for data analysis. The level of evidence will be assessed by the Grading of Recommendations, Development and Evaluation (GRADE) instrument).

RESULTS

The results will rank the efficacy of drugs used to treat uremic pruritus and assess their safety.

CONCLUSION

This study is the first to compare the efficacy and safety of medicines for uremic pruritus based on network analysis and will provide evidence and ideas for the treatment of uremic pruritus.

INPLASY REGISTRATION NUMBER

No. INPLASY202090103.

Interventions for itch in people with advanced chronic kidney disease

BACKGROUND

Itch in patients with chronic kidney disease (CKD) is common, often very distressing and associated with depression, reduced quality of life, and increased death. The most common first-line treatment has been the use of antihistamines despite the lack of substantial evidence for its use for uraemic itch. Few recommendations and guidelines exist for treatment.

OBJECTIVES

We aimed to determine: 1) the benefits and harms (both absolute and relative) of all topical and systemic interventions for the treatment of uraemic itch, either alone or in combination, when compared with placebo or standard care; and, 2) the dose strength or frequency, stage of kidney disease or method of dialysis used (where applicable) in cases where the effects of these interventions vary depending on co-interventions.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 17 December 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in adults with CKD stages 4 or 5 comparing treatments (pharmacological, topical, exposure, dialysis modality) for CKD associated itch to either placebo or other established treatments.

DATA COLLECTION AND ANALYSIS

Two authors independently abstracted study data and assessed study quality. Data were analysed using a random effects meta-analysis design estimating the relative effects of treatment versus placebo. Estimates of the relative effects between treatments are included where possible. For continuous measures of severity of itch up to three months, mean difference (MD) or standardised mean difference (SMD) were used. When reported, adverse effects were tabulated. The certainty of the evidence was estimated using GRADE.

MAIN RESULTS

Ninety-two RCTs, randomising 4466 participants were included. Fifty-eight studies (3285 participants) provided sufficient data to be meta-analysed. Of these, 30 compared an intervention to a placebo or control. The 10 cm Visual Analogue Scale (VAS) was the dominant instrument utilized for itch reporting and the Duo score was used in a minority of studies. GABA analogues including, gabapentin and pregabalin, reduce itch in patients with CKD (5 studies, 297 participants: 4.95 cm reduction, 95% CI 5.46 to 4.44 lower in VAS compared to placebo; high certainty evidence). Kappa opioid agonists, including nalfurafine also reduced itch in this population (6 studies, 661 participants: 1.05 cm reduction, 95% CI 1.40 to 0.71 lower in VAS compared to placebo; high certainty evidence). Ondansetron had little or no effect on itch scores (3 studies, 183 participants: 0.38 cm reduction, 95% CI 1.04 lower to 0.29 higher in VAS compared to placebo; high certainty evidence). Reduction in the severity of itch was reported with oral montelukast, turmeric, zinc sulfate and topical capsaicin. For all other interventions, the certainty of the evidence was low to moderate, and the interventions had uncertain effects on uraemic pruritus. Six studies have disclosed significant financial support from their respective manufacturers, six were affected by lack of blinding, and 11 studies have 15 participants or less. Older, smaller RCTs often failed to follow intention-to-treat protocols with unexplained dropouts after randomisation. Adverse effects were generally poorly and inconsistently reported across all RCTs. No severe adverse events were reported for any intervention.

AUTHORS' CONCLUSIONS

The RCTs of this meta-analysis contain a large array of interventions with a diverse set of comparators. For many interventions, trials are sparse. This served to make informative meta-analysis challenging. Of all treatments for uraemic pruritus, gabapentinoids (gabapentin and pregabalin) were the most studied and show the greatest reduction in itch scores. Further RCTs, even of the scale of the largest trials included in this review, are unlikely to significantly change this finding. Kappa-opioid agonists (mainly nalfurafine) also may reduce itch, but indirect comparison suggests a much more modest effect in comparison to GABA analogues. Evidence for oral montelukast, turmeric, zinc sulfate, and topical capsaicin also showed an itch score reduction. However, these reductions were reported in small studies, and warrant further investigation. Ondansetron did not reduce itch. It is somewhat unlikely that a further study of ondansetron will change this result.

Efficacy of uremic pruritus treatment in patients undergoing hemodialysis, a network meta-analysis for randomized clinical trials

INTRODUCTION

Uremic pruritus is very common in hemodialysis or renal failure patients, there were lots of available treatments such as gabapentin, pregabalin, ondansetron, etc. However, there is no quantified study comparing these treatments together, it is impossible to conduct a clinical trial involving so many treatments, so we conduct a network meta-analysis to compare them.

METHOD

We collected mean difference and standard error of visual analogue scale data as outcome. In total we collected 15 articles, 15 articles, 1180 subjects and 6 treatments included to this study.

RESULTS

In these comparisons, gabapentin showed the largest effect MD: 5.19, 95%CI [3.77, 6.61], anti-histamine MD: 4.65, 95%CI [2.22, 7.07] and pregabalin MD: 4.62, 95%CI [2.71, 6.62] showed a similar effect. Opioid pathway related treatment also showed a significant but not so large effect MD: 2.45, 95%CI [0.41, 4.49]. Ondansetron and Doxepin didn't show a significant improvement among placebo, the overall quantifying heterogeneity I²=43.1%. There is no statically difference between gabapentin, pregabalin and anti-histamine treatments.

CONCLUSIONS

So we conclude that gabapentin, pregabalin and anti-histamine has a similar efficacy on pruritus control.

Emerging Therapeutic Options for Chronic Pruritus

Chronic pruritus, defined as an unpleasant sensation resulting in a need to scratch that lasts more than 6 weeks, is a prevalent and bothersome symptom associated with both cutaneous and systemic conditions. Due to complex pathogenesis and profuse contributing factors, chronic pruritus therapy remains challenging. Regardless of the well-established antipruritic properties of classic pharmacotherapy (topical therapy, phototherapy and systemic therapy), these methods often provide insufficient relief for affected individuals. Owing to the growing interest in the field of pruritic research, further experimental and clinical data have emerged, continuously supporting the possibility of instigating novel therapeutic measures. This review covers the most relevant current modalities remaining under investigation that possess promising perspectives of approval in the near future, especially opioidergic drugs (mu-opioid antagonists and kappa-opioid agonists), neurokinin-1 receptor antagonists, biologic drugs, Janus kinase inhibitors, ileal bile acid transporter inhibitors, aryl hydrocarbon receptor agonists and histamine H₄ receptor antagonists.

Current and emerging systemic treatments targeting the neural system for chronic pruritus

INTRODUCTION

Pruritus is a debilitating symptom that significantly affects the quality of life of patients who suffer from it. Many current and emerging systemic treatments targeting the neural system have been successful in treating itch of various underlying etiologies.

AREAS COVERED

A complete search of the PUBMED and Google Scholar databases was completed and literature pertinent to current and emerging systemic anti-pruritic drugs which target the neural system was compiled. The purpose of this review is to give the reader with an overview of the current and emerging systemic therapeutic options which target the neural system for chronic pruritus. The authors then provide the reader with their expert perspectives on the future of these therapies.

EXPERT OPINION

Exciting new anti-pruritic therapies targeting the neural system which show promise include NK-1 inhibitors, opioid receptor modulators, and drugs targeting specific itch receptors such as Mrgpr, Na_v1.7, and PAR2, as well as selective GABA modulators. Future studies should be conducted in order to fully understand these exciting therapeutic options.

CKD-Associated Pruritus: New Insights Into Diagnosis, Pathogenesis, and Management

Chronic kidney disease–associated pruritus (CKD-aP) is a common, troubling and in some cases debilitating problem for patients with CKD and end-stage renal disease. Despite a prevalence rate of approximately 20% in CKD and 40% in end-stage renal disease, and a clear association with poorer psychosocial and medical outcomes, this condition is often underreported by patients and overlooked by health care providers. This is likely due, in part, to uncertainty regarding its pathogenesis and treatment. Most commonly, CKD-aP is attributed to toxin build-up, peripheral neuropathy, immune system dysregulation, or opioid dysregulation. Prior treatment studies of CKD-aP have targeted these potential etiologies but have been limited by noncontrolled design, small sample size, and non-uniform definitions of CKD-aP. Recently, several large, randomized controlled trials targeting opioid dysregulation have yielded promising results. These trials have spurred new hope for understanding and treating this condition.

Itching as the onset of pain (part 2)

Itching of the skin is a particularly unpleasant subjective sensation that causes the need to scratch. Physiological itching occurs in response to environmental irritants (friction, insect crawling, temperature changes, etc.) and disappears after elimination of the cause. Pathological itching is caused by changes in the skin or throughout the body and causes a strong need to get rid of itching by combing or any other method. Itching is a common symptom of local (dermatological) or general (systemic) disease. It can be limited (localized) or diffuse (generalized).One of the causes of itching is often noted endocrine diseases and metabolic disorders: hyper- and hypofunction of the thyroid gland, diabetes mellitus and hyperparathyroidism. In thyroid hyperfunction, generalized (inconstant and little-pronounced) itching of the skin is observed in the clinical picture only in 10 % of patients. It is accepted that itching of the skin in thyrotoxicosis syndrome is due to increased activity of kinin in combination with an increase in major metabolism and an increase in body and skin temperature (123).Itching caused by impaired bile secretion is characteristic of many diseases of the liver: primary biliary cirrhosis, sclerosing cholangitis, viral hepatitis caused by cholestasis medications and other causes of obstructive jaundice. It is in these cases that prurigo is usually generalized, but in some typical cases it is more pronounced on the feet and palms. With this pathology, itching is caused by obstruction of the biliary tract, however, and to this day, no close correlation has been found between serum bilirubin and the severity of itching.If it was previously thought that itching in pathology of the peripheral or central nervous system, such as multiple sclerosis, neuropathy, compression or irritation of nerves (e.g., paraesthetic dorsalgia, brachioradial itching) is also a significant symptom, then modern studies prove that in more cases, itching is not characteristic of most pathologies of the nervous system, so after a detailed anamnesis, examination and initial research, the patient should be referred to a related specialist, except in cases of about obvious postherpetic neuropathy, painless paresthesia, or brachioradial itching, which can often be guided in the provision of primary care.Instead, there are some psychological conditions and a number of psychiatric illnesses (obsessive-compulsive disorders, depression, and parasite illusions) that are most commonly diagnosed with the exclusion method. Neurotic squabbles are scattered on the body of the excorii, covered with scales that may occur in any area of the body that the patient may reach, but are often limited by limbs.

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.

Development and Validation of a Uremic Pruritus Treatment Algorithm and Patient Information Toolkit in Patients With Chronic Kidney Disease and End Stage Kidney Disease

CONTEXT

Uremic pruritus (UP) affects up to half of all patients with kidney disease and has been independently associated with poor patient outcomes. UP is a challenging symptom for clinicians to manage as there are no validated guidelines for its treatment.

OBJECTIVES

The study aimed to develop and validate an algorithm and patient information toolkit for the treatment of UP in patients with kidney disease.

METHODS

The study involved a literature search and development of an initial draft algorithm, followed by content and face validation of this algorithm. Validation entailed three rounds of interviews with six nephrology clinicians per round. Participants assessed the relevance of each component of the algorithm and then rated a series of statements on a scale of 1-5 to assess face validity of the algorithm. After each round, the content validity index (CVI) of each algorithm component was calculated, and the algorithm was revised by the study team in response to findings. This process was followed by a second study that developed and validated a patient information pamphlet and video.

RESULTS

Algorithm validation participants were affiliated with three institutions and included seven physicians, four registered nurses, three nurse practitioners, three pharmacists, and a dietician. The average CVI of the algorithm components across all three rounds was 0.89, with 0.80 commonly cited as the lower acceptable limit for content validation. More than 78% of participants rated each face validity statement as "Agree" or "Strongly Agree". For the patient information tools, five clinicians and 15 patients were included in validation. The average CVI was 1.00 for both tools, and the average face validity was 92%.

CONCLUSION

A treatment algorithm and patient information toolkit for managing UP in patients with kidney disease were developed and validated through expert review. Further research will be conducted on implementation of the treatment algorithm and evaluating patient-reported outcomes.

Pruritus Associated With Chronic Kidney Disease: A Comprehensive Literature Review

The prevalence of pruritus in chronic kidney disease (CKD) patients has varied over the years, and some studies suggest the prevalence may be coming down with more effective dialysis. Chronic kidney disease-associated pruritus (CKD-aP), previously called uremic pruritus, is a distressing symptom experienced by patients with mainly advanced chronic kidney disease. CKD-aP is associated with poor quality of life, depression, anxiety, sleep disturbance, and increased mortality. The incidence of CKD-aP is decreasing given improvements in dialysis treatments, but approximately 40% of patients with end-stage renal disease experience CKD-aP. While the pathogenesis of CKD-aP is not well understood, the interaction between non-myelinated C fibers and dermal mast cells plays an important role in precipitation and sensory stimulation. Other causes of CKD-aP include metabolic abnormalities such as abnormal serum calcium, parathyroid, and phosphate levels; an imbalance in opiate receptors is also an important factor. CKD-aP usually presents as large symmetric reddened areas of skin, often at night. Managing CKD-aP is a challenge. Research in this area is difficult because most studies are not comparable given their small group samples, study designs, and lack of standardized study measures. The most commonly used treatment is a combination of narrow-band ultraviolet B phototherapy and a μ-opioid receptor antagonist such as naltrexone.

Emerging Treatments and Novel Pathways in Pruritus

Itch treatment is a major challenge in the dermatologist’s practice. We encounter patients suffering from pruritus on a regular basis, and often lack diverse treatment options to adequately respond to the patients’ needs. In the last 20 years, novel pathways have been investigated that were beyond the scope of histamine. Although most did not result in a molecule available on the Canadian market, it is interesting and important as health care providers to stay up to date with new neuronal pathways involved in itch transmission and potential new therapeutic options. In this review, we will discuss pathways targeted in new topical treatments such as antagonist of proteinase-activated receptor-2, the endocannabinoid system, neurotrophins and tropomyosin-related kinase A receptor, the transient receptor potential-vanilloid or transient receptor potential-melastatine ion channels. New systemic therapies are now focusing on antagonizing the neurokinin receptor, modulating the opioidergic system, or targeting itch cytokines such as interleukin-31.

Can we use psychoactive drugs to treat pruritus?

Pruritus is a frequent complaint both in dermatology and general medicine. This burdensome symptom has a complex and multifactorial pathogenesis, with the key involvement of central nervous system in its development. Psychoactive drugs (psychopharmaceuticals) encompass several therapeutic groups utilized mainly in psychiatry. However, these drugs are occasionally used in dermatological practice and may contribute to alleviation of pruritus in a variety of cutaneous and extracutaneous disorders. This review article summarizes the role of H1-antihistamines, antidepressants, antipsychotics and antiepileptics in managing pruritus.

The Use of Naltrexone in Dermatology. Current Evidence and Future Directions

Naltrexone is a competitive opioid receptor antagonist approved as supportive treatment in alcohol dependence and opioid addiction. At a dose of 50-100 mg daily, naltrexone is used off-label in dermatology for the treatment of trichotillomania and different types of pruritus. At a dose as low as 1- 5 mg per day, naltrexone demonstrates immunomodulatory action i.e. modulates Toll-like receptors signaling, decreases release of proinflammatory cytokines (tumor necrosis factor, interleukin-6, interleukin- 12), inhibits T lymphocyte proliferation, down-regulates the expression of chemokine receptors and adhesion molecules. The efficacy of standard and low doses of naltrexone in a variety of dermatological disorders has been reported. These include diseases such as familial benign chronic pemphigus (Hailey-Hailey disease), dermatomyositis, systemic sclerosis, psoriasis and lichen planopilaris. Optimistic preliminary findings, low cost of therapy and good tolerance make naltrexone a promising alternative therapy or adjunct drug in dermatology.

Dermatologic manifestations in end stage renal disease

Skin manifestations are commonly seen in end stage renal disease (ESRD). Skin involvement in this population can be extensive and dramatically worsen quality of life. Close observation of the skin and nails of ESRD patients by clinicians allows for timely diagnosis and treatment, which ultimately improves quality of life and reduces mortality. In this article we focus on the cutaneous changes most commonly seen in ESRD patients. PubMed/Medline database search was done for published literature on skin manifestations in ESRD patients. All the available literature was reviewed and relevant articles were used to discuss about clinical features, pathogenesis, histology and treatment of each skin disorder in ESRD patients. Most commonly encountered skin manifestations in patients with ESRD are pruritus, xerosis, pigmentation changes, nail changes, perforating disorders, calcifying disorders, bullous dermatoses and nephrogenic systemic fibrosis. Skin manifestations in ESRD can be difficult to treat and multiple comorbidities in this patient population can exacerbate these disorders. Many of the treatment options are experimental with evidence largely derived from the case reports and small clinical trials. More large-scale trials are needed to firmly establish evidence based treatment guidelines. Prompt evaluation and management of these disorders improve morbidity and quality of life in ESRD patients.

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.