Comparing the efficacy of pre-operative intravenous and oral paracetamol for lower wisdom tooth extraction.

Paracetamol is an effective, safe analgesic for the management of mild to moderate pain. It is of proven benefit for the management of pain after extraction of third molar teeth and other surgical procedures, and available in oral, rectal, and Intravenous (I.V.) formulation. Since 2003, a stable I.V. solution of paracetamol supplanted propacetamol, easing complexity of administration with no loss of effectiveness. I.V. administration has been described as the route of choice for rapid analgesia after surgery, with evidence it can replace or reduce consumption of other analgesic preparations.

I.V. administration achieves a rapid, reliable serum paracetamol level within the therapeutic antipyretic range, although analgesic effect may not directly equate to antipyretic effect. Oral paracetamol also has a good clinical pedigree. Its effect depends on absorption which itself depends on the circumstances of administration.

I.V. paracetamol has enjoyed a sharp increase in popularity, particularly in the perioperative setting. We felt it useful to investigate with a consistent pain model whether oral paracetamol is inferior in clinical effect to I.V. paracetamol and enable clinicians to make informed prescribing decisions.  

Project aims

By randomized, double-blinded trial, we aimed to determine whether preoperative oral paracetamol provides inferior postoperative analgesia to preoperative i.v. paracetamol.

 

Project findings and impact

There is no perfect pain model, although the third molar extraction model is widely accepted and used to compare analgesia for both prevention and treatment of postoperative pain. The use of a VAS (Visual Analog Scale) grades the patient’s perception of their pain and is subject to inter-rater variability, in the region of + 20 on a 0 – 100 scale.

A total of 128 patients completed the study. There were no significant differences in baseline characteristics or intraoperative variables between the groups. The study was designed to reveal whether Oral Paracetamol (OP) is inferior to Intravenous Paracetamol (IP), with an inferiority margin of 20 per cent. The number of patients reporting satisfactory analgesia at 1 hour with a VAS rating of ≤30-mm were 15 (OP) and 17 (IP), respectively.

The secondary outcome measure of the mean (standard deviation) VAS (mm) for the whole of each group was 52 (22) for OP and 47 (22) for IP. Analysis of confidence intervals indicates that oral paracetamol is not inferior to I.V. paracetamol. The median survival (90 per cent CI) to rescue analgesia request was 54.3 (51.2 –57.4) minutes in Group OP and 57.3 (55.4 – 59.2) minutes in Group IP; there was no significant difference in this measure.

We believe that with facilities to give oral medication some time before surgery, the perceived benefits of I.V. paracetamol over oral are less than may be imagined and unlikely to significantly alter the patient’s perception of pain after surgery. With this information, clinicians may choose to avoid the additional costs and risks attached to the I.V. preparation. 

Research team

Natalie Edelman

Queen Victoria Hospital, East Grinstead

S. Fenlon

J. Collyer

J. Giles

H. Bidd

Eastbourne District General Hospital

M. Lees

J. Nicholson

Kent and Canterbury Hospital

R. Dulai

University of Southampton

M Hankins

 

Output

Partners

Queen Victoria Hospital, East Grinstead

Eastbourne District General Hospital

Kent and Canterbury Hospital

University of Southampton