When should diclofenac be given in ambulatory surgery: preoperatively or postoperatively?

Study Objective: To determine the optimum time of administration of diclofenac in patients undergoing ambulatory knee arthroscopy: either preoperatively or postoperatively.
Design: Randomized, double-blind study.
Setting: Ambulatory surgical unit in a tertiary referral hospital.
Patients: 127 ASA physical status I and II patients undergoing ambulatory knee arthroscopy.
Interventions: Patients were randomized into three groups. The Preop group received 50 mg of potassium diclofenac orally 1 hour preoperatively and a placebo 30 minutes postoperatively. The Pre+postop group received 25 mg of potassium diclofenac 1 hour preoperatively and 25 mg diclofenac 30 minutes postoperatively. The Postop group received a placebo 1 hour before surgery and 50 mg of potassium diclofenac 30 minutes postoperatively.
Measurements and Main Results: The Postop group received a placebo 1 hour preoperatively and 50 mg of potassium diclofenac 30 min postoperatively. Postoperatively, patients used intravenous patient-controlled analgesia (PCA) with fentanyl. Total fentanyl consumption was recorded. During the recovery period, pain was assessed using a visual analog scale (VAS) at 30-minute intervals. Pain was assessed in both legs at rest, on flexion, and extension of the knee. There were no significant differences in pain scores either at rest or on movement of the operative knee among the Preop, Pre+postop, and Postop groups. The consumption of fentanyl via PCA showed no significant differences among the groups.
Conclusions: There is no difference in pain relief whether diclofenac is given preoperatively or postoperatively in patients undergoing unilateral ambulatory knee arthroscopy. Preoperative and postoperative treatment with diclofenac potassium is equally effective.