Effect of oxycodone patient-controlled intravenous analgesia after cesarean section: a randomized controlled study

BACKGROUND: Oxycodone is a semisynthetic μ-opioid receptor agonist with a potentially good analgesic efficacy in visceral pain. This study aims to compare the efficacy of oxycodone with sufentanil patient-controlled intravenous analgesia (PCIA). METHODS: One hundred and twenty primiparas undergoing elective cesarean section were randomized into four groups by different drugs of PCIA: group S (sufentanil 100 μg), group OS1 (sufentanil 70 μg, oxycodone 30 mg), group OS2 (sufentanil 50 μg, oxycodone 50 mg), and group O (oxycodone 100 mg). Ramosetron 0.3 mg was added to each group. In all groups, drugs were diluted to 100 mL and managed with a continuous infusion of 1 mL·h(−1), a bolus dose of 2 mL, and a lockout interval of 15 min. The maximum dose of PCIA per hour was 10 mL. After surgery, pain scores, PCIA doses, and side effects were compared among groups. RESULTS: At all time points (6, 12, and 24 h after surgery), Numerical Rating Scale (NRS) of uterine cramping pain (NRS-U) scores in group O were lower than those in groups OS1 and S (P<0.008) and NRS-U scores in groups OS2 and OS1 were lower than that in group S (P<0.008). NRS of moving into the sitting position (NRS-S) scores in group O were lower than those in the other groups (P<0.008). NRS-S scores in group OS2 were lower than those in groups OS1 and S (P<0.008). At 12 and 24 h after surgery, NRS of incision pain at rest (NRS-R) scores in group O were lower than those in the other groups (P<0.008). At all time points, NRS-R scores in group OS2 were lower than those in groups OS1 and S (P<0.008). The number of PCIA boluses and amount of opioid consumption in group O were lower than those in groups OS1 and S at all time points (P<0.008). CONCLUSION: Oxycodone PCIA may be more effective than sufentanil PCIA for pain relief after cesarean section but the incidence of side effects needs further investigation.