Conditions: Chronic Pruritus
Keywords: arsenic exposure naloxone placebo single-blind randomized trial
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 126
Healthy volunteers: no

Brief summary:
The purpose of this study is to assess the efficacy and safety of sublingual naloxone in the treatment of chronic itch in patients under arsenic exposure.

Detailed description:
This study aims to determine the efficacy and safety of sublingual naloxone in the treatment of chronic, refractory itch in patients under long-term arsenic exposure. In this study, 120 subjects with a moderate-to-severe symptom of itching (numeric rating scale, NRS≥3) will be recruited and randomly treated with either sublingual naloxone (60 subjects) or placebo (60 subjects). The severity of itching will be evaluated in the wash out phase, baseline, and one week after the treatment through reporting of subjective symptomatology (itch NRS) via the interview. Quality of sleep measured by the Pittsburgh Sleep Quality Index (PSQI) and Dermatology Life Quality Index (DLQI) will serve as the secondary outcome.

Arms:
arm 1: Naloxone at an sublingual dose of 0.4 mg daily will be given to each subject. arm 2: Sublingual placebo will be given to each subject.

Interventions: intervention 1: Naloxone intervention 2: Placebo
Intervention descriptions: intervention 1: Naloxone at an sublingual dose of 0.4 mg daily for one week will be given to each subject. Subjects will self-administer the drug at supervision in the primary care center. intervention 2: Placebo will be given to each subject for one week. Subjects will self-administer the drug at supervision in the primary care center.

Protocol document:
Prot_SAP_000.pdf: 
Study Protocol and Statistical Analysis Plan 
 
Treatment of Chronic Itch in Patients Under Arsenic Exposure With Sublingual Naloxone: A Double-
blind Randomized Controlled Trial 
 
NCT number: 2018/NAL/CSU/PRU 
Date: 2020.10.1 
 
Study design 
To test whether the inhibition of β-endorphin (μ-opioid) receptor alleviates itch in patients under chronic 
arsenic exposure, we conducted a randomized, double-blind, placebo-controlled trial. We randomly assigned 
patients to naloxone (0.4 mg/qd, sublingual) and placebo (0.4 mg/qd, sublingual) using a computer-generated 
sequence of random numbers during January 2019 to March 2019. The trial consisted of a one-week 
treatment period and a one-week withdrawl period. The primary outcome (severity of itch) was evaluated 
using the NRS through a face-to-face interview on baseline (Day 0) and the last day of the treatment period 
(Day 7), and a telephone interview on the last day of the withdrawl period (Day 14). The participants were 
also inquired about the possible adverse events of naloxone such as headache, sleep difficulty, sickness, and 
dizziness in each interview. 
 
Inclusion and exclusion criteria 
The inclusion criteria include: the participants must be above 18 years, be able to understand the study 
protocol and sign informed consent voluntarily, and report moderate-to-severe itch (NRS≥3). Participants 
were excluded if they used anti-histamines, anti- inflammatory, anti-pruritic, analgesic, antidepressant, or 
anti-epileptic agents within 2 weeks prior to the study, or had a history of pruritic skin diseases such as 
eczema and psoriasis. 
 
Statistical analysis 
In the randomized controlled trial, an intention-to-treat (ITT) analysis was performed to evaluate the efficacy of 
naloxone. The last observation carry-forward (LOCF) imputation method was used for unmeasured data in 
drop-out participants. Mixed effect models were used to estimate the efficacy, by constructing a model: Y 
= β0 + β1Group + β2Time + β3(Group×Time) + ei + υij, where β3 is the estimate for efficacy; ei and υij refer to 
the errors between individuals and within an individual (repeated measurements), respectively. Statistical 
analyses were performed in R Statistical Software 3.4.1. The significance level for all statistical tests was 0.05.