Nalmefene effectively relieves thoracic epidural opioid-induced pruritus without affecting analgesia: a randomized...

Pruritus is a prominent side effect of neuraxial opioids. Pruritus is an unpleasant sensation that leads to scratching and discomfort. This trial was aimed to study nalmefene's efficacy for treating epidural opioid-induced pruritus and its effect on postoperative patient-controlled epidural analgesia (PCEA).

We recruited 166 patients who developed postoperative pruritus due to epidural opioid analgesia. Patients were randomized to the nalmefene group or control group and received either 0.5 µg/kg nalmefene or the equivalent volume of saline to evaluate nalmefene's efficacy for treating epidural opioid-induced pruritus and its effect on postoperative PCEA. The primary outcome was the complete relief rate of pruritus within 24 hours after the treatment. Secondary outcomes included postoperative pain scores, other PCEA-related adverse events, itch scores, and the time of itching relief.

A total of 160 patients were included in the final analysis. The complete pruritus relief rate in the nalmefene group was significantly higher than that in the control group within 24 hours after the treatment (68 of 80; 85% vs. 51 of 80; 63.7%, P=0.002). The median Visual Analog Scale (VAS) pain score, the incidence of other PCEA-related adverse events, and itch scores showed no difference. The Kaplan-Meier curves showed that intravenous nalmefene reduced the median [interquartile range (IQR)] time of itching relief from 15.62 (7.59-23.65) to 1.5 (0.84-2.16) hours (P<0.001). The multivariable analysis indicated that female patients without allergic history were associated with more complete relief of itching.

A single dose of intravenous nalmefene could relieve postoperative pruritus from epidural opioids without affecting analgesic effects.

The study was retrospectively registered in the Chinese Clinical Trial Registry (ChiCTR2000039596) on November 2, 2020.