Pain control with paracetamol from a sustained release formulation and a standard release formulation after third molar surgery: a randomised controlled trial

Objective To compare the analgesic efficacy and safety of a sustained relea se (SR) paracetamol formulation (Panadol Extend) with a standard immediate release (IR) formulation (Panadol) after third molar surgery. Design A multi-centre, double-blind, randomised clinical trial. Methods Patients received either a single oral dose of SR paracetamol or IR paracetamol for pain after the removal of at least one impacted third mola r requiring bone removal under general anaesthesia. Post-operative pain and pain relief assessments were undertaken at time intervals up to 8 hours. G lobal assessments of effectiveness were made at 4 and 8 hours. Any adverse events were also recorded. Results Of 627 randomised patients, 314 were treated with SR paracetamol an d 313 with IR paracetamol. In the per protocol population at 4 hours, 35.1% of the 252 patients on SR paracetamol rated the study medication as very g ood or excellent compared with 27.7% of the 258 patients on IR paracetamol. There were few statistically significant differences among the secondary p arameters but where they did occur they favoured SR paracetamol. Trends in favour of SR paracetamol were observed among the secondary parameters and t hese tended to emerge at the later time points. For example, while there wa s no statistically significant difference in time to re-medication between the treatment groups, the estimated time to re-medication was longer for pa tients treated with SR paracetamol (4 hr 5 min) compared with IR paracetamo l (3 hr 10 min). The high rate of re-medication observed is consistent with that reported for IR paracetamol using the post-operative dental pain mode l(4,6). No difference was observed between the SR paracetamol and IR parace tamol treatment groups in distribution, incidence or severity of adverse ev ents, Conclusions SR paracetamol and IR paracetamol are clinically and statistica lly equivalent. While SR paracetamol and IR paracetamol were similar in ter ms of both onset of analgesia and peak analgesic effect, SR paracetamol had a longer duration of activity than IR paracetamol. The safety profiles of SR paracetamol and IR paracetamol were found to be very similar.