Efficacy of Duloxetine on the Duration of Spinal Anesthesia and Acute Post-Operative Pain after Hip Surgery Prospective Randomized Controlled Study

Abstract
Background: Prevention and treatment of post-operative pain continue to be a major challenge in post-operative care. Preemptive analgesia has been shown to be effective in reducing the severity of post-operative pain. Serotonin and norepinephrine are involved in the modulation of endogenous analgesic mechanisms, Duloxetine is a selective Serotonin-Norepinephrine Reuptake Inhibitor (SNRI) mainly used in the treatment of depression, anxiety and chronic pain. The analgesic effect of duloxetine is believed to result from increased activity of serotonin (5-HT) and Norepinephrine (NE) within the CNS.
Aim of Study: The aim of this study was to evaluate the efficacy of pre-operative duloxetine on the duration of spinal anesthesia, severity of post-operative pain, and total analgesic consumption.
Methods and Material: Sixty patients aged 18-60 years, ASA I-II, scheduled for elective hip surgery were randomized into two equal groups: Duloxetine group (Group D): 30 patients received duloxetine 60mg on two divided doses 30mg every 12h for three days before the operation, 2h pre-operative and 12h after the surgery. Control group (Group C): 30 patients received placebo capsules by the same way as duloxetine group.
Measurements: Demographic data (age, Body Mass Index (BMI), sex), Hemodynamic (HR, MAP), duration of surgery, duration of spinal anesthesia, post-operative pain was assessed by the Visual Analog Scale (VAS) at 0, 2, 6, 12, 24 and 48h after the surgery, the time at which rescue analgesia was given and total analgesic consumption in 48h was recorded.
Results: There was no significant difference between both groups as regards to demographic data, hemodynamics (HR & MAP), duration of surgery and duration of spinal anesthesia. VAS score was significantly lower in in Group D than Group C. Time till administration of first rescue analgesia was significantly prolonger in Group D than Group C.
Conclusions: We conclude from this study that pre-operative administration of oral duloxetine 60mg daily divided into two doses 30mg every 12hr for 3 days significantly decreases post-operative pain and total analgesic consumption and improve patient psychology with a significant reduction in associated side effects but has no effect on the duration of spinal anesthesia.