Renal itch

Spice Up Your Kidney: A Review on the Effects of Capsaicin in Renal Physiology and Disease

Capsaicin, the organic compound which attributes the spicy flavor and taste of red peppers and chili peppers, has been extensively studied for centuries as a potential natural remedy for the treatment of several illnesses. Indeed, this compound exerts well-known systemic pleiotropic effects and may thus bring important benefits against various pathological conditions like neuropathic pain, rhinitis, itching, or chronic inflammation. Yet, little is known about the possible biological activity of capsaicin at the kidney level, as this aspect has only been addressed by sparse experimental investigations. In this paper, we aimed to review the available evidence focusing specifically on the effects of capsaicin on renal physiology, as well as its potential benefits for the treatment of various kidney disorders. Capsaicin may indeed modulate various aspects of renal function and renal nervous activity. On the other hand, the observed experimental benefits in preventing acute kidney injury, slowing down the progression of diabetic and chronic kidney disease, ameliorating hypertension, and even delaying renal cancer growth may set the stage for future human trials of capsaicin administration as an adjuvant or preventive therapy for different, difficult-to-treat renal diseases.

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.

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.

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.

Prevalence of chronic kidney disease-associated pruritus among adult dialysis patients: A meta-analysis of cross-sectional studies

Chronic kidney disease (CKD)-associated pruritus is a common adverse symptom in patients with end-stage renal disease treated by dialysis. Herein, a systematic review and meta-analysis of the prevalence of CKD-associated pruritus among adult dialysis patients was conducted.An electronic search of PubMed, Web of Science, Elsevier, Wanfang, and Chinese National Knowledge Infrastructure databases was conducted from inception to November 23, 2016, and all cross-sectional studies that reported the prevalence of CKD-associated pruritus in dialysis were collected. The pooled prevalence was estimated by random-effects model. Potential publication bias was evaluated by the funnel plot as well as Begg and Egger tests.After rigorous screening, a total of 42 studies conducted on 11,800 patients were included in this study. The overall prevalence of CKD-associated pruritus among adult dialysis patients was 55% (95% confidence interval [CI], 49-61, I = 97.6%), the stratification of which was 55% (95% CI, 45-65, I = 94.7%) in men and 55% (95% CI, 46-65, I = 93.3%) in women. In hemodialysis (HD) patients, the prevalence of CKD-associated pruritus was 55% (95% CI, 49-62, I = 97.9%), while in peritoneal dialysis (PD) patients, it was 56% (95% CI, 44-68, I = 89.9%). The prevalence of CKD-associated pruritus for mean dialysis duration <40 months was 56% (95% CI, 48-63, I = 75.1%), while that for mean dialysis duration ≥40 months was 50% (95% CI, 36-64, I = 99.1%).The prevalence of CKD-associated pruritus is high in HD and PD. The prevalence among adult dialysis patients is comparable between China and foreign countries as well as between females and males. Studies with the similar disease definition and analysis of the effects of risk factors on CKD-associated pruritus are needed.

Uremic Pruritus

Renal itch is a localized or generalized itch, affecting patients with chronic renal failure, where there is no primary skin disease and no systemic or psychological dysfunction that might cause pruritus. Uremic pruritus (UP) is an unpleasant sensation, rarely appearing in earlier stages of chronic kidney disease. Renal transplantation is the definite solution for that problem. The prevalence of UP has been reduced during the last years, possibly, due to a more efficient dialysis, with more biocompatible filters.

During the last decades a big number of substances were considered to be etiologic factors of UP, and an even bigger number of therapeutic substances appeared with promising potentials and conflicting results in the course of their use. The main reason for this disorientation is the lack of sound evidence on the pathogenetic mechanisms that may potentiate UP.

‘Inflammatory’ and ‘opioid’ hypothesis are the best studied and the reduction of UP is a fact. Nevertheless the mechanisms of the pathogenesis of UP are still under investigation and a long way has to be done in order to achieve more definite results.

Pruritus in Kidney Disease

Pruritus is a common and distressing symptom in patients with chronic kidney disease. The most recent epidemiologic data have suggested that approximately 40% of patients with end-stage renal disease experience moderate to severe pruritus and that uremic pruritus (UP) has a major clinical impact, being associated strongly with poor quality of life, impaired sleep, depression, and increased mortality. The pathogenesis of UP remains largely unclear, although several theories on etiologic or contributing factors have been proposed including increased systemic inflammation; abnormal serum parathyroid hormone, calcium, and phosphorus levels; an imbalance in opiate receptors; and a neuropathic process. UP can present somewhat variably, although it tends to affect large, discontinuous, but symmetric, areas of skin and to be most symptomatic at night. A variety of alternative systemic or dermatologic conditions should be considered, especially in patients with asymmetric pruritus or other atypical features. Treatment initially should focus on aggressive skin hydration, patient education on minimizing scratching, and optimization of the aspects of chronic kidney disease care that are most relevant to pruritus, including dialysis adequacy and serum parathyroid hormone, calcium, and phosphorus management. Data for therapy specifically for UP remain limited, although topical therapies, gabapentin, type B ultraviolet light phototherapy, acupuncture, and opioid-receptor modulators all may play a role.

Pruritus epidemiology and quality of life

The burden of chronic pruritus is increasingly recognized as significant worldwide. As wet-laboratory researchers investigate the pathophysiology of chronic pruritus, epidemiologists and health services researchers are quantifying the impact of pruritus by incidence, prevalence, and quality of life measures. Outcomes researchers are also investigating factors that may predict chronic pruritus incidence and severity. Such efforts will direct resources for research, public health intervention, and clinical care.

Pruritus in Systemic Diseases: A Review of Etiological Factors and New Treatment Modalities

Pruritus is the most frequently described symptom in dermatology and can significantly impair the patient's quality of life. In 10–50% of adults with persistent pruritus, it can be an important dermatologic clue for the presence of a significant underlying systemic disease such as renal insufficiency, cholestasis, hematologic disorder, or malignancy (Etter and Myers, 2002; Zirwas and Seraly, 2001). This review describes the presence of pruritus in different systemic diseases. It is quite important to discover the cause of pruritus for providing relief for the patients experiencing substantial morbidity caused by this condition.

A prospective study of cutaneous abnormalities in patients with chronic kidney disease

There are diverse ways in which the skin is affected by chronic kidney disease (CKD). Various specific and nonspecific skin abnormalities are observed in patients with CKD. The aim of the study was to document the prevalence of skin diseases that commonly occur in patients with CKD on medical treatment and dialysis. A total of 99 patients with CKD were examined for evidence of skin diseases. Ninety-six had at least one cutaneous abnormality attributable to CKD. The most prevalent finding was xerosis (66.7%), followed by pallor (45.45%), pruritus (43.4%), and cutaneous pigmentation (32.3%). Other cutaneous manifestations included dermatitis (27.27%); Kyrle's disease (17.17%); fungal (8.08%), bacterial (11.1%), and viral (5.05%) infections; purpura (10.1%); gynecomastia (4.04%); and yellow skin (5.05%). The common nail changes were half and half nails (36.36%) and onycholysis (13.13%). CKD is associated with various cutaneous abnormalities caused either by the disease or by treatment, the most common being xerosis and pruritus. The dermatologic complications can significantly impair the quality of life in certain individuals; therefore, earlier diagnosis and treatment is important to improve their quality of life.

Cutaneous manifestations in end-stage renal disease

The prevalence of chronic kidney disease has increased over the last years. The effects of this disease are complex and may lead to dysfunction of multiple organs, including the skin, with most patients presenting with at least one dermatologic alteration. Sometimes these symptoms can be the first clear sign of kidney disease. This article discusses the skin manifestations related to severe renal impairment or end-stage renal disease (ESRD), which are divided into nonspecific and specific, and reviews the clinical features, etiopathogenesis and therapeutic options for these dermatoses. Early recognition and treatment reduce morbidity and improve these patients' quality of life.

[Skin diseases in hemodialysis and kidney transplant patients]

Recently, the world is facing an escalate in the incidence of chronic kidney disease (CKD). Databases containing information about patients in end stage renal disease (ESRD), especially in the United States, were the sources of initial information about it. Brazil has the third largest population on dialysis in the world, and there are about 680 dialysis centers, spread across all units of the federation in the present, providing treatment to an estimated population of almost 90,000 patients. Cutaneous involvement in the chronic renal failure is characterized by a number of manifestations, which may be related to three processes: the primary renal disease, the uremic state, or the therapeutic measures used in their handling. The skin changes in these two classes of patients, dialysis and transplant recipients, have been the subject of several studies. n recent years, however, great progress has been achieved in these two therapeutic modalities, which may have changed not only the type of the dermatologic disorders associated with these two conditions, but also their intensity or frequency. This article aims to yield an update as to the topic skin diseases in hemodialysis and kidney transplant patients.

"I need to lead my own life in any case"--a study of patients in dialysis with or without a partner

OBJECTIVE

To elicit psychological and psychosocial problems existing in patients in dialysis and their partners, its being felt that the diversity involved has important implications for how service in dialysis units is delivered to patients and their partners.

METHODS

The results of a series of interviews of 39 patients in dialysis and 21 partners of theirs, each interview individual, concerning their ways of thinking and their feelings and the behaviour, were analyzed in qualitative and content-oriented terms.

RESULTS

Five basic themes could be identified: importance of treatment being individualized, dependency on an apparatus, consequences of the disease and its treatment, hopes for the future, and thoughts concerning life and death. Diversities relating to age, civil status, cultural and gender matters were disclosed.

CONCLUSION

The interview approach illustrated the importance of extended professional and individualized support in handling psychological and psychosocial disparities and needs in order to make treatment regimes more acceptable to the persons involved.

PRACTICE IMPLICATIONS

Suggestions are made concerning efforts to improve the care of patients receiving dialysis, and the importance of working with the patients and those closest to them in multidisciplinary teams.

Effectiveness of Topical Chia Seed Oil on Pruritus of End-stage Renal Disease (ESRD) Patients and Healthy Volunteers

BACKGROUND

Several studies have been performed to evaluate the efficacy of dietary n-3 fatty acid for patients with renal dysfunction. While about 40% to 80% of patients with end-stage renal disease (ESRD) complain about pruritus and xerosis, there are few reports on the effects of topical n-3 fatty acid on these symptoms.

OBJECTIVE

In order to investigate the possible beneficial effects of topical n-3 fatty acid, oils extracted from chia (Salvia hispanica) seed were formulated into topical products, the effects of which were measured.

METHODS

Five healthy volunteers having xerotic pruritus symptoms and 5 patients with pruritus caused by either ESRD or diabetes were involved in this study. A topical formulation containing 4% chia seed oils were applied for an 8-week duration. Subjective itching symptoms were assessed on a 6-point scale, as were other skin functions, namely transepidermal water loss and skin capacitance.

RESULTS

After the 8 weeks of application, significant improvements in skin hydration, lichen simplex chronicus, and prurigo nodularis were observed in all patients. A similar improvement was also observed among healthy volunteers with xerotic pruritus. Improvement of epidermal permeability barrier function and skin hydration, represented by trans-epidermal water loss and skin capacitance, respectively, were also observed. No adverse effects were observed in all the tested patients and volunteers.

CONCLUSION

Chia seed oil can be used as an adjuvant moisturizing agent for pruritic skin, including that of ESRD patients.

Evaluation of chronic pruritus in older patients

Chronic pruritus, one of the main symptoms in dermatologic diseases, is often intractable and has a high impact on a patient´s quality of life. In addition to dermatologic disorders, chronic pruritus is associated with systemic and neurologic, as well as psychologic, diseases. Aging skin is considered to be more susceptible to pruritic disorders. Thus, owing to demographic changes, pruritus is becoming more prevalent. The elderly are often afflicted with comorbidities and polypharmacy, which can complicate diagnosis and therapy. In this review we present a rational work-up adapted to the special premises and needs of geriatric patients. This may facilitate the choice of suitable therapeutic regimens.

Uraemic pruritus: clinical characteristics, pathophysiology and treatment

Pruritus is a common complication of end-stage renal disease (ESRD), affecting about one-third of dialysis patients. It is a chronic, unpleasant symptom with a strong negative impact on patients' quality of life, often inducing sleeplessness and mood disorders. Recent data show that it is also associated with increased mortality. The pathogenesis of uraemic pruritus (UP) is multifactorial. Triggering factors may include uraemia-related abnormalities (particularly involving calcium, phosphorus and parathyroid hormone metabolism), accumulation of uraemic toxins, systemic inflammation, cutaneous xerosis, and common co-morbidities such as diabetes mellitus and viral hepatitis. Recent findings suggest that the neurophysiology of itch is similar to that of pain; this has led to the hypothesis that the two phenomena also closely interact in ESRD patients, who often also experience uraemic neuropathy. The management of UP needs to address several different issues, such as optimization of dialysis efficacy and skin hydration, and correction of calcium-phosphorus metabolism abnormalities. A wide range of antipruritic drugs have been suggested for the treatment of UP, although most of them have only been tested in small, uncontrolled trials, which have yielded conflicting results. Antihistamines are now known to have little or no efficacy, although they are still often prescribed. Novel neurotropic drugs such as gabapentin, along with opioid receptor modulators such as nalfurafine, appear to be effective and well tolerated, but their efficacy has not yet been directly compared. Finally, physical therapies, including UV radiation, may also have a role in patients with refractory symptoms.

Pattern of skin and nail changes in chronic renal failure in Nepal: a hospital-based study

Chronic renal failure, regardless of its cause, often produces specific dermatological abnormalities, which can develop long before failure manifests clinically. Our aim was to study the clinical pattern of skin and nail changes in chronic renal failure and also study the associations of these changes with age, sex, etiology and duration of the chronic renal failure. A total of 104 diagnosed cases of chronic renal failure were included in the study over a period of 1 year. Equal numbers of age- and sex-matched individuals were taken as controls. The male : female ratio was 1.4:1. The mean duration of chronic renal failure was 19 +/- 20 months. Among cases and controls, 72% and 16% had skin changes, respectively. Xerosis was the most common of the skin changes (28%), followed by hyperpigmentation (20%), pruritus (15%), infectious diseases (5%) and other skin changes (33%) in chronic renal failure patients. Abnormal nail changes were seen in 82% of the cases compared to only 8% of the controls. In the cases, white nail was most common followed by brown and half-and-half nail. Pruritus was significantly higher in the dialysis group whereas the nail changes were significantly higher in the non-dialysis group. The skin and nail changes were common in chronic renal failure and manifested in various forms. Thus, thorough inspection of the integument might reveal markers of occult renal disease.

Generalized pruritus: a prospective study concerning etiology

BACKGROUND

Generalized pruritus can often be the primary manifestation of systemic disease.

OBJECTIVE

To determine how frequently generalized pruritus had a systemic etiology in an outpatient population seen in a dermatology department and whether any identifiable patient characteristics meant a systemic explanation of generalized pruritus was more likely.

METHODS

A prospective controlled study of 55 patients with generalized pruritus and 41 healthy age- and sex-matched control subjects. Clinical data were collected from patients and laboratory parameters investigated in both patients and healthy control subjects to determine the frequency of systemic disease in each group.

RESULTS

Of 55 patients, 12 had a systemic cause of pruritus. Pruritus was the initial symptom of systemic disease in eight of these patients. The underlying diseases included hypothyroidism, chronic lymphocytic leukemia, hepatitis C, hepatitis B, diabetes mellitus, lung cancer, uremia, and iron deficiency anemia. Of these, iron deficiency anemia was the most common cause. Compared with the control group, mean serum hemoglobin, iron, and cyanocobalamin (vitamin B(12)) levels in patients with generalized pruritus were lower. No other patient characteristics were statistically associated with systemic causes of pruritus.

CONCLUSION

Generalized pruritus was the initial symptom of a systemic disease in 8 of 55 patients presenting to a dermatology outpatient clinic with this complaint. A number of underlying diseases were identified, of which the most common was iron deficiency anemia.

An update on pruritus associated with CKD

The prevalence of chronic kidney disease (CKD) and end-stage renal disease is increasing worldwide. Despite improvements in dialysis methods, including the development of novel biocompatible membranes and ultrapure dialysate, CKD-associated pruritus remains a common and significant public health issue. Not only does this distressing symptom profoundly impact on quality of life and sleep, recent evidence showed that pruritus also was associated with poor patient outcome. Nonetheless, nephrologists and other health care professionals often fail to recognize and adequately address the pruritus associated with CKD. The pathophysiological mechanism of CKD-associated pruritus is poorly defined, and, as a result, the development of specific therapies has proved to be a challenge. The purpose of this review is to highlight the importance of this neglected topic by providing an overview of recent epidemiological studies, outcomes data, proposed pathophysiological mechanisms, and emerging treatment options.

Elucidating issues stressful for patients in predialysis and dialysis: from symptom to context

Biopsychosocial problems experienced by renal disease patients were studied within a contextual framework the patients themselves defined, the findings being related to sociodemographic and medical data. Participants were 72 predialysis patients and 73 patients being treated by haemodialysis or peritoneal dialysis (106 men and 39 women, aged 18-84 years). Both stress-related global and situational measures of biopsychosocial problems were assessed by questionnaire. Factor analyses revealed five factors--Bodily problems; Work and leisure time; Sleep, cramps and itching complaints; Financial problems; and Dependence-- explaining 71.1 per cent of the total variance. Fatigue loaded both on Bodily problems and Work and leisure time. Sleep disturbances, itching of the skin and muscle cramps were more stressful for the dialysis than the predialysis patients. Also, fatigue, inability to work and limitation on vacation activities appeared more stressful for the dialysis group. The study supports the usefulness of a contextual approach for gaining a better general understanding of renal disease patients' problems.

Diffuse trichostasis spinulosa in chronic renal failure

Trichostasis spinulosa is a relatively common but underdiagnosed disorder of the pilosebaceous follicles in which there is follicular hyperkeratosis of a dilated vellus hair follicle with retention of successive telogen hairs arranged in parallel among keratinaceous material. The condition is apparent as dark follicular plugs in the affected areas, most commonly affecting the face (nose and cheeks) or the trunk (interscapular area in particular). We describe a 33-year-old Indian man who was on haemodialysis for chronic renal failure and who developed unusually widespread trichostasis spinulosa over almost the entire body including the lower limbs over a period of 18 months.

Ultraviolet phototherapy for pruritus

Ultraviolet-based therapy has been used to treat various pruritic conditions including pruritus in chronic renal failure, atopic dermatitis, HIV, aquagenic pruritus and urticaria, solar, chronic, and idiopathic urticaria, urticaria pigmentosa, polycythemia vera, pruritic folliculitis of pregnancy, breast carcinoma skin infiltration, Hodgkin's lymphoma, chronic liver disease, and acquired perforating dermatosis, among others. Various mechanisms of action for phototherapy have been posited. Treatment limitations, side effects, and common dosing protocols are reviewed.

κ-Opioid System in Uremic Pruritus: Multicenter, Randomized, Double-Blind, Placebo-Controlled Clinical Studies

Uremic pruritus is a very common and frustrating condition for both patients and clinicians because no treatment has been demonstrated to be effective in relieving the itch. In this report, nalfurafine, a new kappa-opioid receptor agonist, was used to treat uremic pruritus in patients who were undergoing routine hemodialysis. Two multicenter, randomized, double-blind, placebo-controlled studies enrolled 144 patients with uremic pruritus to postdialysis intravenous treatment with either nalfurafine or placebo for 2 to 4 wk. A meta-analysis approach was used to assess the efficacy of nalfurafine. Statistically significant reductions in worst itching (P = 0.0212), itching intensity (P = 0.0410), and sleep disturbances (P = 0.0003) were noted in the nalfurafine group as compared with placebo. Improvements in itching (P = 0.0025) and excoriations (P = 0.0060) were noted for the nalfurafine-treated patients. Nalfurafine showed similar types and incidences of drug-related adverse events as did placebo. Nalfurafine was shown to be an effective and safe compound for use in this severely ill patient population.

Pruritus in hemodialysis patients

Background

Pruritus is one of the most bothersome symptoms in patients on maintenance hemodialysis (HD), however little progress is seen in our understanding of its pathogenesis. The aim of this study was to evaluate the frequency of pruritus in HD patients in Tehran, Iran, and to correlate its presence and intensity with relevant clinical and laboratory parameters.

Methods

One hundred sixty-seven patients on maintenance HD at three out-patient HD units were enrolled in the study. Itch intensity was scored as mild, moderate and severe. Some relevant clinical and laboratory parameters (age, sex, xerosis, presence of neuropathy, duration of dialysis, history of atopy and laboratory findings including hematocrit, creatinine, urea, calcium, phosphorus, parathyroid hormone [PTH] and alkaline phosphatase) were evaluated.

Results

Pruritus was found in 41.9% of patients. The intensity of itching was mild, moderate and severe, in 51.4%, 11.4% and 37.7% of patients, respectively. In 22 patients (31.4%) pruritus intensified during and after dialysis. There was no significant difference in the serum levels of creatinine, blood urea nitrogen, calcium, phosphorus, alkaline phosphatase, PTH and hematocrit between patients with and without pruritus. Age, sex, xerosis, underlying renal disease, history of atopy and duration of haemodialysis were not significantly different between the two groups. However, neuropathy was significantly more common in the pruritic group (63.8% versus 42.1%) (pv = 0.006).

Conclusion

Clinical neuropathy was the only significant finding in the pruritic group in our study. This finding justifies further research on nerve function and neurotransmitters in hemodialysis patients and the introduction of new drugs targeting neuropathy.

Gabapentin therapy for pruritus in haemodialysis patients: a randomized, placebo-controlled, double-blind trial

BACKGROUND

Uraemic pruritus is a common and distressing symptom in patients on haemodialysis for chronic renal failure. Gabapentin is an anticonvulsant that alleviates neuropathic pain. We conducted a double-blind, placebo-controlled, crossover study to assess its effectiveness against renal itch.

METHODS

We enrolled in the trial 25 adult patients on haemodialysis who were asked to daily record the severity of their pruritus on a visual analogue scale. The patients were randomly assigned to receive gabapentin for 4 weeks followed by placebo for 4 weeks or the reverse sequence. Gabapentin or placebo were administered thrice weekly, at the end of haemodialysis sessions.

RESULTS

The mean pruritus score of the cohort before the study was 8.4 +/- 0.94. After placebo intake, it decreased to 7.6 +/- 2.6 (P = 0.098). The score of four patients decreased by >50% following placebo. After gabapentin administration, the mean score decreased significantly, to 1.2 +/- 1.8 (P = 0.0001), although one patient's symptoms did not improve significantly. No patient dropped out of the study due to adverse effects from gabapentin.

CONCLUSIONS

Our study shows that gabapentin is safe and effective for treating uraemic pruritus in haemodialysis patients. Our results also support the neuropathic hypothesis of uraemic pruritus.

Hyperosmolar Solutions Selectively Block Action Potentials in Rat Myelinated Sensory Fibers: Implications for Diabetic Neuropathy

Diabetic neuropathy is a common complication of diabetes mellitus patients. It is a wide range of abnormalities affecting proximal and distal peripheral sensory and motor nerves. Although plasma hyperosmolality is a common finding in diabetes mellitus, the effects of hyperosmolality on conduction of various sensory signal components have not been addressed in detail. Here we show that in rat dorsal root ganglion (DRG) preparations from normal rats, hyperosmolar solutions (360 mmol/kg, containing increased glucose, sucrose, NaCl, or mannitol) produce a selective block of signal propagation in myelinated sensory A-fibers. In compound action potential (CAP) recordings with suction electrodes, peak A-fiber CAP amplitude was selectively decreased (20%), while the C-fiber peak remained intact or was slightly increased. Hyperosmolar solutions had smaller effects on conduction velocity (CV) of both A- and C-fibers (approximately 5% decrease). Hyperosmolality-induced CAP changes could not be observed during recordings from isolated spinal nerves but were evident during recordings from desheathed spinal nerves. In intracellular recordings, hyperosmolar solutions produced a block of spinal nerve-evoked action potential invasion into the somata of some A-fiber neurons. Removal of extracellular calcium completely prevented the hyperosmolality-induced CAP decreases. Based on these data, we propose that the decreased CAP amplitudes recorded in human patients and in animal models of diabetes are in part due to the effects of hyperosmolality and would depend on the extracellular osmolality at the time of sensory testing. We also hypothesize that hyperosmolality may contribute to both the sensory abnormalities (paresthesias) and the chronic pain symptoms of diabetic neuropathy.

Paroxetine in the treatment of severe non-dermatological pruritus: a randomized, controlled trial

Severe pruritus may be an idiopathic phenomenon or associated with advanced systemic disease. It is one of the most distressing and difficult to treat symptoms. Uncontrolled studies have suggested that, in patients experiencing severe pruritus, paroxetine appeared to have a rapid anti-pruritic effect. This study was a prospective double-blind, randomized within patient comparison of paroxetine and placebo. The intensity of pruritus was measured subjectively with a numerical analogue scale. The primary endpoint of the trial was the mean pruritus score, measured for seven days after randomization and after cross-over. The secondary endpoint was individual global response to the treatment. Response was defined as at least 50% reduction of intensity of pruritus in the last three days of the treatment period vs. baseline. Adverse effects and patient satisfaction and preferences were also recorded. Twenty-six patients were included in the study; 17 of them had solid tumors, 4 had hematological malignancies and 5 had various nonmalignant or idiopathic conditions. Eight patients had drug-induced pruritus (none opioid-induced), 7 patients had paraneoplastic pruritus and 3 had cholestatic pruritus. After a run-in period, patients were randomly assigned to treatment with 20 mg paroxetine or placebo. The crossover took place after 7 days. Two patients discontinued treatment because of adverse effects of paroxetine. Twenty-four patients treated with paroxetine had lower pruritus intensity scores over the 7 treatment periods (mean+/-SE=5.2+/-0.32) as compared to placebo (mean+/-SE=6.0+/-0.32). Mean difference between placebo and paroxetine was 0.78 (95% CI=0.37-1.19). Nine of twenty-four patients (37.5%) fulfilled criteria of response. The onset of anti-pruritic action was observed usually after 2-3 days, irrespective of the order of treatment. The outcome of this study indicates that paroxetine is effective in the treatment of severe pruritus of non-dermatological origin.

Benefits of fish oil supplementation for hemodialysis patients

A literature review on fish oil supplementation in the population undergoing chronic hemodialysis therapy suggests that supplementation may be beneficial for various challenges to health and well-being prevalent in this population. One study indicated that pruritus symptoms improved with fish oil supplementation, but not with supplementation with two other oils. In a study designed to determine whether fish oils could prevent vascular access graft thrombosis, graft patency rates were approximately 76% in the fish oil and approximately 15% in the placebo group (P>.03). In a pilot study, subjects given fish oil required 16% less erythropoietin and experienced a 3.6% increase in serum albumin levels. Some studies suggest that fish oil supplementation in hemodialysis patients is cardioprotective, with one study finding that "fish eaters" are half as likely to die as "non-fish eaters." Potential risks of supplementation include gastrointestinal distress, prolonged bleeding, and vitamin A toxicity, although the likelihood of serious side effects is probably low. Dietitians are in a position to advise physicians and/or patients regarding appropriate dosages and ways to minimize risks when supplementation seems warranted. Future research could compare the benefits of fish consumption with those of fish oil supplementation and explore the benefits of other n-3 fatty acid sources, such as flaxseed.

Itch

Itch is a common skin sensation, with substantial effects on behaviour. Neurophysiological research has permitted accurate definition of neural pathways of itch, and has confirmed the distinctiveness of itch pathways in comparison with pain. A clinical classification of itch, based on such improved understanding, describes the difference between peripheral (pruritoceptive) and central (neurogenic or neuropathic) itch. New specific and sensitive investigational methods in people and animals enable us to better understand this bothersome symptom, and have important clinical implications. We describe the clinical classification of itch, new findings on neuropathophysiology of itch, methods for assessment, and improved treatments.

A randomized, placebo-controlled, double-blind trial of ondansetron in renal itch

BACKGROUND

Renal itch is a relatively common and distressing problem for patients with chronic renal failure. Ondansetron, a serotonin type 3 receptor antagonist was developed for relief of chemotherapy induced nausea. Recently, anecdotal reports describe relief of renal itch with ondansetron.

OBJECTIVES

We performed a double-blind randomized placebo-controlled trial to objectively assess the effectiveness of ondansetron in renal itch.

PATIENTS AND METHODS

With approval from the local ethical committee, 24 patients on haemodialysis were enrolled in the trial. On a random basis 14 patients were blindly allocated to the ondansetron-placebo sequence and 10 to the placebo-ondansetron sequence. Baseline values for itch were obtained for 7 days before the treatment period and there was a 7-day washout between the treatment periods. During the treatment patients received either 8 mg of ondansetron three times a day or a placebo tablet three times a day for 2 weeks. Patients were asked to record the severity of their pruritus on a visual analogue scale (VAS) twice a day. At the end of the study patients were asked blindly which treatment they had preferred.

RESULTS

Seventeen patients completed the trial. Pruritus decreased by 16% (95% CI: 0.5-32%) during active treatment and by 25% (95% CI: 9-41%) during treatment with placebo. The change in VAS scores during treatment with ondansetron (P = 0.04) and placebo (P = 0.01) were both significant. Eleven patients expressed a preference, seven for placebo and four for ondansetron.

CONCLUSIONS

Our results show that ondansetron is no better than placebo in controlling renal itch.

Cutaneous nephrology

There are numerous cutaneous findings that may be related to coexistent renal disease. An astute clinician may use careful skin examination to make early diagnosis of renal conditions in some cases, and institute appropriate therapy as soon as indicated.

Pruritus in systemic disease: mechanisms and management

Pruritus is the most common symptom of skin disease. Even in the absence of primary cutaneous findings, severe and extensive pruritus often is associated with systemic disease. This review considers briefly the physiology of pruritus and discusses the various systemic diseases often accompanied by this bothersome symptom. In addition to exploring the possible mechanisms and potential therapies of itching in selected disorders, this review presents general recommendations for evaluating patients with unexplained pruritus and management guidelines for alleviating their discomfort.

Skin changes and tumours after renal transplantation

Skin involvement in chronic renal failure is characterised by a multitude of different aspects. Apart from the typical yellow-brown discolouration of the skin, most often patients complain of pruritus and xerosis cutis. A marked actinic elastosis is noticed. Dialysis treatment alters and partly aggravates these pre-existing skin conditions. When chronic renal failure leads to a kidney transplantation, some of the reversible skin pathology, e.g. pruritus, xeroderma, tends to ameliorate, but a high tendency to develop malignancies becomes prominent.

Vanilloid receptor ligands: hopes and realities for the future

Neurons possessing C-fibers transmit nociceptive information into the central nervous system and participate in various reflex responses. These neurons carry receptors that bind capsaicin, recently identified as the vanilloid VR1 receptor. Excitation of these cells by capsaicin is followed by a lasting refractory state, termed desensitisation, in which the neurons fail to respond to a variety of noxious stimuli. Desensitisation to capsaicin has a clear therapeutic potential in relieving neuropathic pain and ameliorating urinary bladder overactivity, just to cite 2 important examples. Vanilloids may also be beneficial in the treatment of benign prostate hyperplasia (BPH). Since the majority of elderly patients have neuropathic pain co-existent with urinary incontinence and/or BPH, a drug that ameliorates pain and improves urinary symptoms at the same time promises to be of great clinical value in geriatric medicine. In fact, capsaicin has already been shown to have a role in the treatment of conditions that can arise in the elderly, including herpes zoster-related neuropathic pain, diabetic neuropathy, postmastectomy pain, uraemic itching associated with renal failure, and urinary incontinence. The potent VR1 agonist resiniferatoxin, now in phase II clinical trials, appears to be superior to capsaicin in terms of its tolerability profile. Recent discoveries enhance the therapeutic potential of vanilloids. The recognition that VR1 also functions as a principal receptor for protons and eicosanoids implies that VR1 antagonists may be of value in the treatment of inflammatory hyperalgesia and pain. Animal experimentation has already lent support to this assumption. The discovery of VR1-expressing cells in the brain as well as in non-neural tissues such as the kidney and urothelium places VR1 in a much broader perspective than peripheral pain perception, and is hoped to identify further, yet unsuspected, indications for vanilloid therapy. The realisation that VR1 and cannabinoid CB1 receptors have overlapping ligand recognition properties may also have far-reaching implications for vanilloid therapy. In fact, arvanil, a combined agonist of VR1 and CB1 receptors, has already proved to be a powerful analgesic drug in the mouse. From academic molecular biology laboratories to industrial drug discovery centres to the clinics, there is a steady flow of new data, forcing us to constantly revise the ways we are thinking about vanilloid receptor ligands and their hopes and realities for the future. This review covers the most promising current trends in vanilloid research with special emphasis on geriatric medicine.

Ondansetron: a selective 5-HT(3) receptor antagonist and its applications in CNS-related disorders

Ondansetron is a selective 5-hydroxytryptamine(3) (5-HT(3)) receptor antagonist that has been introduced to clinical practice as an antiemetic for cancer treatment-induced and anesthesia-related nausea and vomiting. Its use under these circumstances is both prophylactic and therapeutic. It has a superior efficacy, safety and pharmacoeconomic profile compared with other groups of antiemetics, namely antidopaminergics, antihistamines and anticholinergics. However, its place in the management of anticipatory and delayed vomiting in cancer treatment and as a rescue antiemetic in surgical patients needs to be further explored. Furthermore, recent animal and human research also reflects its possible novel application in the treatment of other disease states, such as alcoholism, cocaine addiction, opioid withdrawal syndrome, anxiety disorders, gastrointestinal motility disorders, Tourette's syndrome and pruritus. This review revisits the widespread physiological and pathological effects of 5-HT and discusses both the basic science literature and the clinical developments responsible for the conventional and novel uses of ondansetron. In addition, new discoveries relating to the effects of ondansetron on other receptors/channels and their possible therapeutic applications are presented.