Rectal and parenteral paracetamol, and paracetamol in combination with NSAIDs, for postoperative analgesia

Background. We have reviewed the analgesic efficacies of rectal and parenteral paracetamol and tested the evidence for a possible additive analgesic effect of the combination of paracetamol with a non-steroidal anti-inflammatory drug (NSAID) in postoperative pain. Methods. Randomized controlled trials were evaluated. Outcome measures were pain scores and demand for supplementary analgesia. Results. Eight studies compared rectal paracetamol with placebo. One study of single-dose administration of rectal paracetamol 40-60 mg kg(-1) and three studies of repeat dosing with 14-20 mg kg(-1) showed significant analgesic efficacy, while studies of a single dose of 10-20 mg kg(-1) were negative. Ten studies compared parenteral paracetamol with placebo and eight studies showed improved pain relief with paracetamol. Of the nine studies comparing paracetamol with a combination of paracetamol and an NSAID, six studies showed improved pain relief for the combination while only two of the six studies comparing an NSAID with a combination of an NSAID and paracetamol showed improved pain relief for the combination. Conclusions. Considering the few studies available, evidence was found of a clinically relevant analgesic effect of rectal and parenteral paracetamol. Concurrent use of paracetamol and an NSAID was superior to paracetamol alone but no evidence was found of superior analgesic effect of the combination compared with the NSAID alone.