Review: single dose, oral paracetamol reduces moderate to severe postoperative pain.

Is single dose paracetamol (acetaminophen) efficacious and safe for acute postoperative pain?METHODSData sources: Cochrane Controlled Trials Register (Cochrane Library, Issue 3, 2002), Specialised Register of the Cochrane Pain, Palliative, and Supportive Care group (November 2002), Medline (1966 to May 1996), PubMed (1996 to November 2002), EMBASE/Excerpta Medics (1980-96), Oxford Pain Relief database (1950-94), and reference lists of retrieved articles.Study selection and assessment: published, double blind, randomised controlled trials (RCTs) that compared single dose, oral, immediate release paracetamol with placebo for moderate to severe postoperative pain (>30 mm on visual analogue scale [VAS]) in adults and allocated >/=10 patients to each treatment group. Exclusion criteria: postpartum trials of pain from uterine cramps alone; pain relief assessed by clinicians, nurses, or carers (rather than patient report); trials <4 hours or no data from 4-6 hours after administration of dose. 2 reviewers independently assessed individual study quality using the 3 item Jadad scale and a consensus score (maximum 5 points).Outcomes: proportion of patients with >/=50% pain relief at 4-6 hours (based on hourly patient reports over 4-6 h using validated pain scales) and adverse effects.MAIN RESULTS47 trials (n=4186) met the selection criteria. Trials assessed pain after dental surgery (n = 25); elective general, gynaecological, urological, and orthopaedic surgery (n = 12); and episiotomy and Caesarean section (n= 10). Meta-analysis was done using a fixed effects model. Mean proportion of patients experiencing >/=50% pain relief over 4-6 hours was greater in patients who received paracetamol (325, 500, 600/650, 975/1000, or 1500 mg) than in those who received placebo (table). Paracetamol, 975/1000 mg, did not differ from placebo for drowsiness/sleepiness/somnolence, dizziness, nausea, vomiting, or headache.CONCLUSIONSingle dose, oral paracetamol at doses ranging from 325-1500 mg provides >/=50% pain relief of moderate to severe postoperative pain for 4-6 hours, with few adverse effects recorded.