Randomized AND “prospective” AND “postoperative analgesia” AND “clinical” AND “trial” AND “pain” AND “patient” AND “surgery” AND “acetaminophen” OR “paracetamol” NOT “spectrometry” NOT “cytokine” NOT “receptor” NOT “children” NOT “damage” NOT “overdose” NOT “temperature” NOT “suicide” NOT “hepatocyte” NOT “bioavailability” NOT “oral paracetamol” NOT “neonatal” NOT “osteoarthritis” NOT “oral propacetamol” NOT “propacetamol