A randomised comparison of regular oral oxycodone and intrathecal morphine for post-caesarean analgesia

Primary post-caesarean analgesia based on oral opioid has not been adequately studied. This approach may show a good side-effect profile and high satisfaction and avoid neuraxial complications.

In a double-blind, double-dummy, placebo-controlled clinical trial 120 women were randomised to receive either sustained-release oral oxycodone 20mg in the recovery room followed by immediate-release oxycodone 10mg 6-hourly for the first 24h (group O) or intrathecal morphine 100mug at the time of spinal anaesthesia (group I). All women received regular postoperative diclofenac, paracetamol and standardised supplemental analgesia.

One hundred and eleven women completed the study. The area under the curve for pain scores to 24h did not differ significantly between groups for pain at rest (P=0.465) or on movement (P=0.533). Numerical pain scores were low and similar, except at rest at 12h (group I 1 [0-2] vs. group O 2 [1-3]; P=0.030). The time to first analgesic request was similar but additional postoperative analgesics were required more often in group O (82% vs. 63%, P=0.034). Group O more frequently reported high worst pain scores (score 4-10 in 87% vs. 64%, P=0.007). Pruritus was more common and more severe in group I (87% vs. 56%, P=0.001). At 24h maternal satisfaction with the analgesic regimen was lower in group O (P=0.010).

Oral oxycodone produced comparable postoperative pain relief to intrathecal morphine with a lower incidence of pruritus, but was associated with a lower satisfaction score.