Pharmacokinetics of parenteral paracetamol and its analgesic effects in post-operative dental pain.

A double-blind, randomised, crossover trial was undertaken to compare the analgesic effects of a single dose of paracetamol (1000 mg i.v.) with placebo in the immediate post-operative period following removal of impacted lower third molars. There was no significant difference in the pain relief between paracetamol and placebo in the first hour following injection. Thereafter, there was significantly less pain (P less than 0.05) after treatment with paracetamol than after placebo. Plasma concentrations of paracetamol were measured and pharmacokinetic variables were determined. Over the four hour period of investigation there was no clear relationship between analgesia and paracetamol concentration in either central or peripheral compartments.