A double-blind, placebo-controlled study of the tolerability and efficacy of a new kappa-opioid receptor agonist (R-84760) in patients with pain after dental surgery

Objective: To determine the efficacy of a new kappa-opioid receptor agonist (R-84760) in patients with pain after third molar removal. Design: Randomised, double-blind, placebo-controlled study evaluating a sin gle subcutaneous dose of R-84760 7 mug. Setting: Day-stay oral surgery unit. Patients: 72 adult patients who had undergone removal of their impacted thi rd molars under general anaesthesia. Main Outcome Measures: Pain intensity was assessed on a serial visual analo gue scale (VAS) over a 4-hour investigation period. Patients had access to escape analgesics, and when these were taken, the time and dosage were reco rded. Results: For all efficacy variables, R-84760 did not differ significantly f rom placebo (p > 0.05). Nearly all the patients required escape analgesics during the investigation period. Conclusions: R-84760, a kappa agonist, did not show efficacy in the managem ent of postoperative pain after third molar surgery. The finding further hi ghlights the equivocal efficacy of opioids in this pain model.