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.
Uremic pruritus: roles of parathyroid hormone and substance P.
Most patients receiving maintenance hemodialysis have pruritus, but its underlying mechanism remains unknown. Secondary hyperparathyroidism is another common problem in these patients, but its role in uremic pruritus is controversial. Capsaicin can deplete substance P from the peripheral neurons and is known to be effective in the treatment of pain and itching.
                Our purpose was to evaluate the role of parathyroid hormone (PTH) and substance P in uremic pruritus and to elucidate the underlying mechanisms.
                The study contained two phases. In phase I, we analyzed the correlation between the intensity of itching and serum levels of intact PTH. In phase II, patients with moderate to severe pruritus were placed into two groups: one with high PTH levels and one with low levels. A double-blind, placebo-controlled study of capsaicin 0.025% cream was conducted in phase II.
                Serum levels of intact PTH did not correlate with the intensity of pruritus and did not significantly change during treatment with capsaicin or placebo. Capsaicin was significantly more effective in alleviating uremic pruritus than the placebo, and no serious side effects were noted.
                Uremic pruritus is not related to PTH. Substance P may act as a neurotransmitter in uremic pruritus and topical capsaicin can be used in the treatment of localized pruritus.