Efficacy of nalfurafine hydrochloride in patients with chronic liver disease with refractory pruritus: A randomized, double‐blind trial

AIMS: Patients with chronic liver disease sometimes develop cholestasis, which induces severe whole-body pruritus that may disrupt daily activities and sleep. To determine the efficacy of nalfurafine hydrochloride (5 μg), which is a selective κ-opioid receptor agonist, in improving pruritus, we undertook a double-blind placebo-controlled study in patients with chronic liver disease with refractory pruritus. Nalfurafine hydrochloride at 2.5 μg was also used to evaluate the dose-response relationship. METHODS: In total, 318 subjects were randomly assigned to receive the placebo or nalfurafine hydrochloride (2.5 or 5 μg) given orally once daily for 84 consecutive days. Pruritus was assessed based on the visual analog scale and pruritus scores. RESULTS: Changes in the visual analog scale at week 4 (last observation carried forward) were significantly greater in the nalfurafine hydrochloride groups at 28.56 and 27.46 mm in the 2.5 μg and 5 μg groups, respectively, compared to 19.25 mm in the placebo group (P = 0.0022 and 0.0056, respectively). The major adverse drug reactions (ADRs) included pollakiuria (including nocturia), somnolence, insomnia (including middle insomnia), and constipation. Most ADRs were mild. CONCLUSIONS: Nalfurafine hydrochloride (2.5 or 5 μg daily) was effective in the treatment of refractory pruritus in patients with chronic liver disease. Furthermore, no clinically significant ADRs were observed at either dose.