As per the study published in “The Canadian Journal of Anesthesia”, dexamethasone displayed superiority to dexmedetomidine as an intravenous adjunct to prolong bupivacaine-based interscalene blocks analgesic duration in patients undergoing ambulatory arthroscopic shoulder surgery. No additional benefit of using both adjuncts in combination was noted. Researchers undertook this randomized, double-blinded, single-centre, parallel three-group superiority study to compare the efficacy of dexamethasone vs. dexmedetomidine and the advantage of their use in combination in 198 adult individuals undergoing shoulder surgery.

Participants were given preoperative interscalene blocks with 30 mL 0.5% bupivacaine and 50 µg dexmedetomidine or 4 mg dexamethasone or the combination of both as intravenous adjuncts. Analgesic block duration was the major endpoint of this trial while the quality of recovery 15 score on the first day and postsurgery neurologic symptoms in the surgical arm were the secondary endpoints ascertained.

The block durations (n = 195) with dexamethasone and both adjuncts were found to be prolonged when compared to dexmedetomidine, as shown in the table below: 

When examined by linear regression after an unplanned log transformation, the corresponding prolongations of block duration were found to be 59% and 46% respectively. The combined adjuncts did not demonstrate superiority to dexamethasone alone (-8%).

The median [interquartile range] quality of recovery 15 scores (N = 197) were considerably different only between dexmedetomidine (118.5 [41–150]) and dexamethasone (126 [79–149]) but by an amount less than 8-point minimum clinically important difference.

Thus, compared to dexmedetomidine, dexamethasone was found better as an intravenous adjunct for prolongation of pain-relieving duration. The combination of dexmedetomidine and dexamethasone does not yield any extra advantage.