A pramoxine-based anti-itch lotion is more effective than a control lotion for the treatment of uremic pruritus in adult hemodialysis patients

Current topical and systemic therapies for itch

Itch is a common distressing symptom which may be caused by multifactorial aetiologies including inflammatory skin diseases, systemic diseases, neuropathic conditions and psychogenic disorders. Itch is a term used synonymously with pruritus and is defined as acute if it lasts less than 6 weeks or chronic if it persists for more than 6 weeks. It can have the same impact on the quality of life as chronic pain and shares many of the same pathophysiological pathways. Depending on the aetiology of the itch, different pathogenic mechanisms have been postulated with a number of mediators identified. These include histamine, leukotrienes, proteases, neuropeptides, cytokines and opioids, which may activate peripheral itch-mediating C-fibres via receptors on the nerve terminals and central neuronal pathways. Therefore, there is no single universally effective anti-itch treatment available. First-line treatments for itch include topical therapies, such as emollients, mild cleansers (low pH), topical anaesthetics, steroids, calcineurin inhibitors and coolants (menthol). Treatment with systemic therapies can vary according to the aetiology of the chronic itch. Non-sedating antihistamines are helpful in conditions such as urticaria where the itch is primarily histamine mediated. Although the itch of eczema is not mediated by histamine, sedating antihistamines at night are helpful to break the itch-scratch cycle. Chronic itch may also be treated with other systemic therapies, such as anticonvulsants, antidepressants as well as mu-opioid antagonists, kappa-opioid agonists and phototherapy, depending on the cause of the itch. This article summarises the topical and systemic therapies available with our current understanding of the pathophysiology of itch.

Cutaneous manifestations of ESRD

A broad range of skin diseases occurs in patients with ESRD: from the benign and asymptomatic to the physically disabling and life-threatening. Many of them negatively impact on quality of life. Their early recognition and treatment are essential in reducing morbidity and mortality. The cutaneous manifestations can be divided into two main categories: nonspecific and specific. The nonspecific manifestations are commonly seen and include skin color changes, xerosis, half-and-half nails, and pruritus. The specific disorders include acquired perforating dermatosis, bullous dermatoses, metastatic calcification, and nephrogenic systemic fibrosis. This review article describes these conditions and considers the underlying pathophysiology, clinical presentations, diagnosis, and treatment options.

Pharmacological interventions for pruritus in adult palliative care patients

BACKGROUND

Pruritus is not the most prevalent but one of the most puzzling symptoms in palliative care patients. It can cause considerable discomfort and has a major impact on patients' quality of life. In the field of palliative care, pruritus is a symptom occurring in patients with disparate underlying diseases and based on different pathologic mechanisms but ending in the same phenomenon. The pathogenesis of pruritus is complex and not fully elucidated. Thus, it is still very difficult to treat pruritus effectively. Evidence-based treatment approaches are needed.

OBJECTIVES

The objective was to evaluate the efficacy of different pharmacological treatments for preventing or treating pruritus in adult palliative care patients.

SEARCH METHODS

A systematic literature search up to January 2012 was performed and it was updated in August 2012. The following databases were searched: The Cochrane Library (CENTRAL, DARE, CDSR) (2012, issue 8 of 12); MEDLINE (1950 to August 2012); EMBASE (1980 to August 2012) and three other databases. In addition, we searched trials registries and checked the reference lists of all relevant studies, key textbooks, reviews, and websites, and contacted investigators and specialists in pruritus and palliative care regarding unpublished data.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of different pharmacological treatments on preventing or treating pruritus in palliative care patients.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed identified titles and abstracts. Three independent review authors performed assessment of all potentially relevant studies, data extraction, assessment of risk of bias and methodological quality. Results were summarised descriptively according to the different pharmacological interventions and the type of underlying pruritus. Where possible, results were presented in meta-analyses.

MAIN RESULTS

In total, 38 reports comprising 40 studies and 1286 participants were included in the review. Altogether, 30 different treatments for pruritus in four different patient groups were included.The findings of this review indicated that the treatment of pruritus for palliative care patients is challenging and requires an individualistic approach. Results showed that effective therapeutic choices have to be guided by the pathophysiology of the pruritus. Various forms of pruritus occur, especially in the field of palliative care, and sometimes the origin of the pruritus is difficult to determine. Therefore, identifying the underlying cause of pruritus is of prime importance in order to develop tailored treatment plans, even if in palliative care the treatment is focused towards the symptom and not necessarily the underlying disease.Results show that in palliative care patients with pruritus of different natures, treatment with the drug paroxetine, a selective serotonin reuptake inhibitor, may be beneficial. For patients suffering from pruritus associated with HIV infection, indomethacin was described as the most effective drug, although the evidence was weak. For patients suffering from chronic kidney disease-associated pruritus, gabapentin may be an option. An alternative treatment for this patient group seems to be the κ-opioid receptor agonist nalfurafine, which has shown significant amelioration of pruritus and acceptable adverse effects. As they have exhibited a low incidence of adverse effects, rifampicin and flumecinol may be recommended for patients with cholestatic pruritus. The opioid antagonist naltrexone has been shown to offer a therapeutic alternative for patients suffering from uraemic or cholestatic pruritus. However, these drugs are often inappropriate in the palliative population because of the risk of reducing analgesia when giving high doses of naltrexone.

AUTHORS' CONCLUSIONS

The findings of this review indicate that the number of systemic and topical drugs used for the different subforms of pruritus is increasing. Different interventions have been shown to be effective in the treatment of pruritus of different origins. Nevertheless, an optimal therapy for pruritus is constrained due to the limited understanding of crucial itch mediators and receptors in the various subforms of itch. Ideal antipruritic therapies are still lacking, especially for palliative care patients.This systematic review also indicates that there is insufficient evidence to give any concrete recommendations regarding treatment of pruritus in palliative care patients. Due to the very small sample sizes and poor methodological quality of the majority of studies that were included, the results of this review need to be interpreted with caution. Furthermore, the generalizability is questionable. Additional studies, and particularly carefully designed treatment trials, are needed to provide valid evidence for adequate treatment of pruritus in palliative care patients.

Pruritus and renal failure

Patients with renal failure, usually end-stage renal disease (ESRD), commonly are afflicted by severe pruritus. The pathogenesis of ESRD pruritus is unknown, but improving the quality of dialysis can reduce the prevalence and severity of ESRD pruritus. Topical and systemic agents as well as broadband ultraviolet phototherapy can be extremely beneficial. Gabapentin has been recently discovered as an effective agent for the patient with ESRD pruritus. Kappa opiate agonists are promising new therapeutic options.

Topical therapies for pruritus

Itch, or pruritus, is the predominant symptom associated with acute and chronic cutaneous disease, and in some cases may be debilitating. To date, there is no single universally effective anti-itch treatment. Because the pathophysiology of itch in most cutaneous or systemic disorders remains unclear, antipruritic therapy is often directed against a variety of targets, including the epidermal barrier, immune system, or the nervous system. Topical therapy is the mainstay of dermatologic management of acute or localized itch or in patients with contraindications to systemic therapies. This review will summarize current topical therapies to treat pruritus and discuss potential future therapies.

Innovative management of pruritus

Pruritus remains a significant problem facing dermatologists and can be associated with various dermatoses and systemic derangements. At times, one can treat the underlying cutaneous or systemic process to alleviate itch. However, it is frequently challenging to identify the cause of a patient's itch and, in this situation, even more difficult to manage the symptom effectively. In this article, the authors discuss the approach to a patient with generalized pruritus without clinically obvious dermatoses. They also addresses mechanisms and management modalities of itch in common systemic diseases, including cholestasis, uremia, and neuropathic dysfunction.

Therapy of pruritus

IMPORTANCE OF THE FIELD

Pruritus is the predominant symptom of skin disease. Owing to the poorly understood pathophysiology, the development of effective treatment modalities for pruritus has proven to be particularly difficult. At present, there is no universally accepted therapy for itch. The purpose of this review is to provide an update on the treatment of pruritus.

AREAS COVERED IN THIS REVIEW

An overview of current, emerging and possible future therapies for pruritus is provided.

WHAT THE READER WILL GAIN

Insights into possible treatment regimes for pruritus in different clinical scenarios.

TAKE HOME MESSAGE

The therapy of pruritus is challenging and at present takes on an individualistic approach. Recent advancements in the mechanisms that underlie this distressing symptom have identified new targets for future therapy.