The analgesic efficacy and pharmacokinetics of epidural oxycodone after gynaecological laparotomy: a randomized, double-blind, double-dummy comparison with intravenous administration

Abstract

Aim: The aim of the present study was to compare the analgesic efficacy of epidural and intravenous (i.v.) oxycodone at the same dose.

Methods: In this randomized, double-blind, double-dummy clinical trial, 30 women, aged 24-67 years, undergoing elective gynaecological laparotomy, were administrated either i.v. saline and epidural oxycodone 0.1 mg·kg^-1 (EPI group; n = 15) or i.v. oxycodone 0.1 mg·kg^-1 and epidural saline (IV group; n = 15). For multimodal analgesia, patients received i.v. paracetamol and dexketoprofen, and a triple-mixture epidural infusion after the first 4 h postoperatively. The primary outcome was the total dose of i.v. fentanyl for rescue analgesia during the first 4 h postoperatively.

Results: All patients required fentanyl during the first 4 h. The median number of fentanyl doses were three (quartiles 1, 8) in the EPI group and seven (6, 9) in the IV group (mean difference 3.1; 95% confidence interval 0.9, 5.2; P = 0.01). After the first 4 h, the two groups needed a similar total dose of epidural infusion. Patient satisfaction was similarly high in both groups, and both administration routes were well tolerated.

Conclusions: The data support the superiority of epidural oxycodone compared with that of i.v. administration in pain management after laparotomy.

Keywords: analgesia; epidural; laparotomy; oxycodone.

Figure 1

Study flow chart. i.v., intravenous

Figure 2

Fentanyl doses during the first 4 h. The EPI group received intravenous saline and epidural oxycodone; the IV group received intravenous oxycodone and epidural saline

Figure 3

Pain scores at rest (A), while coughing (B) and during wound compression (B). These were lower in the EPI group (who received intravenous saline and epidural oxycodone) than in the IV group (who received intravenous oxycodone and epidural saline) at 30 min (P = 0.026, P = 0.021 and P = 0.029, respectively), and at 60 min (P = 0.003, P = 0.013 and P = 0.023, respectively) after study drug administration. NRS 0–10, 11‐point numerical rating scale* P < 0.05

Figure 4

Plasma (A) and cerebrospinal fluid (B) oxycodone concentrations after the administration of an epidural or intravenous injection of 0.1 mg kg⁻¹ to patients undergoing gynaecological laparotomy in the EPI group (who received intravenous saline and epidural oxycodone; n = 11) and the IV group (who received intravenous oxycodone and epidural saline; n = 7) Oxycodone concentrations in both plasma and cerebrospinal fluid are presented in panel C (C)