Intractable pruritus is a challenging symptom of burn-induced hypertrophic scars. The exact pathogenesis of itch is unknown and conventional management with anti-histamines is often insufficient. Proposed treatments for pruritus include exposure to a cooling surface and maintenance of a well-hydrated environment. The authors of this study developed and examined the effectiveness of a novel guar gum-based hydrogel (CQ-01) impregnated with nanoemulsions containing peppermint oil, menthol or methyl salicylate. The use of oil-in-water nanoemulsions was designed to reduce pruritus exacerbation from the oily organic additives, whilst releasing cooling agents in a controlled fashion. Following on from a pilot study to determine dosage and an exploratory study to prove a beneficial effect, the authors performed a multi-centre, prospective controlled trial on 74 burn patients with severe pruritus. CQ-01 was applied for a 24-hour period and a change in score on the JW scale for assessment of pruritus in burn patients was the measured endpoint. CQ-01 produced statistically and clinically significant reductions in JW score compared to controls, persisting throughout the eight-day trial period, with maximum effect observed on day two. Smaller follow-up studies in 10 individuals suggested that there was no tachyphylaxis phenomenon with repeated use of CQ-01. Use of the same additives in an aqueous cream had only a 24-hour duration of benefit. Skin irritation was the only documented side-effect, which resolved with removal of the hydrogel. Although effectively unblinded (due to smell of the additives), this is a relatively well designed prospective study with clinically significant results supporting the use of cooling hydrogels in the treatment of pruritus. Extrapolation of their use for all pruritic wounds and scars is not discussed in the study, however, similar hydrogels (CQ-03) have subsequently been developed and licensed for that indication. 

Effective symptomatic treatment for severe and intractable pruritus associated with severe burn-induced hypertrophic scars: a prospective multicenter, controlled trial.
Wu J, Xu R, Zhan J, et al.

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Lewis Dingle

St John's Hospital, Livingston, UK.

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