A double-blind randomised controlled trial of paracetamol, diclofenac or the combination for pain relief after caesarean section.

BACKGROUND: Few studies have investigated efficacy and side effects of the combination of diclofenac and paracetamol used for pain relief after major surgery.

METHODS: After ethical approval, 78 patients, presenting for elective caesarean section, were recruited to this double-blind trial and randomised to receive one of three analgesic modalities: paracetamol, diclofenac, or diclofenac and paracetamol. Anaesthesia was standardised with 2.25-2.5 mL of spinal bupivacaine 5 mg/mL in dextrose 80 mg/mL and fentanyl 12.5 mug. Study drugs were given as a suppository at the end of surgery then orally for 24 h. The primary outcome was i.v. morphine use when administered as patient-controlled analgesia for the first 24 h after surgery. Secondary outcomes were visual analogue pain scores measured 2, 4, 6, 10 and 24 h after surgery and verbal rating pain scores and side effects measured 2-hourly for the first 12 h and 4-hourly thereafter.

RESULTS: Patients given the combination of diclofenac and paracetamol required less morphine than did patients given paracetamol alone (mean+/-SD: 33.8+/-23.9 mg versus 54.5+/-28.5 mg, P=0.02). Morphine use in patients given diclofenac alone (42.2+/-26.0 mg) was not significantly different from morphine use in the other two groups. Eight out of 26 patients receiving paracetamol alone were not satisfied with pain management; two required intravenous morphine injections.

CONCLUSIONS: Patients given a combination of diclofenac and paracetamol used 38% less morphine compared to patients given paracetamol.