Comparison of oxycodone with morphine as adjuvant epidural analgesia and its side effects: A systematic review

Abstract

Despite morphine’s ability to deliver effective analgesia, its use as an epidural adjuvant is limited by adverse effects such as nausea, vomiting, and pruritus, which are typically intractable with conventional antihistamines. Another negative effect that we are particularly concerned about is respiratory depression. This systematic review aimed to summarize the evidence based on randomized controlled trials (RCTs) comparing epidural analgesic adjuvants between oxycodone and morphine. We searched the Cochrane Library, PubMed, and EMBASE databases from 1990 until 2021 to find RCTs published in English language, which have investigated pain score and side effects such nausea and vomiting. Three RCTs were included in the final analysis. All of them employed similar argument that epidural analgesic with oxycodone has good analgesic effects at higher dose than morphine. Oxycodone provides analgesic properties equivalent to morphine, but with less nausea and vomiting. We found that epidural analgesic with oxycodone has comparable analgesic effect to morphine, as well as lower side effects on nausea and vomiting at twice morphine doses. Future study is needed to compare epidural oxycodone with morphine in terms of analgesia and adverse effects.