Impact of duloxetine on succinylcholine-induced postoperative myalgia after direct microlaryngoscopic surgeries: Randomized controlled double-blind study.

Background: Succinylcholine is a preferred muscle relaxant for rapid sequence intubation. Postoperative myalgia (POM) is one of its commonest adverse effects with unknown pathogenesis. Various modalities were examined to reduce POM. We hypothesized that duloxetine may reduce the incidence and severity of fasciculation or succinylcholine-induced POM in outpatient surgeries.

Methods: This randomized double-blinded trial involved controlled 70 adult participants scheduled for elective direct microlaryngoscopic surgeries. Before induction of general anesthesia by 2 h, 35 patients received duloxetine 30 mg orally (group D) and 35 patients received similar oral starch placebo capsules (group C). Fasciculations, POM, sedation score, time to first rescue analgesia, total analgesic consumption 24 h after surgery, patients' satisfaction, and adverse effects were recorded.

Results: Incidence of fasciculation was 77.1% and 94.3% in groups D and C (p value = 0.04), whereas its severity was not significant between groups (p value = 0.09). Incidence and severity of POM were significantly lower in group D (p values = 0.004 and 0.021). Positive correlation was recorded between fasciculations and POM scores (r = 0.732 and p < 0.001). Time required for first analgesia was prolonged in group D (p value < 0.001) with less total analgesic consumption (p value = 0.039). The potassium and creatine kinase levels showed significant differences between both groups after 30 min and 24 h, respectively (p value < 0.05). Sedation scores and patients' satisfaction were better in duloxetine group (p value < 0.05) with no severe complications.

Conclusions: Preoperative oral duloxetine 30 mg administration decreased incidence and severity of succinylcholine-related muscle POM and fasciculations. It was also effective in reducing postoperative rescue analgesic requirement with better patients' satisfaction and no serious adverse effects.