Efficacy of Pregabalin as Premedication for Post-Operative Analgesia in Vaginal Hysterectomy

BACKGROUND: Pregabalin, a structural analogue of gamma amino butyric acid (GABA), is shown to be effective in treatment of several types of neuropathic pain, incisional injury, and inflammatory injury. OBJECTIVES: The aim of the present study is to compare the efficacy of two doses (75 mg or 150 mg) of pregabalin with the administration of a placebo for post-operative analgesia in patients undergoing hysterectomy under spinal anesthesia. PATIENTS AND METHODS: A randomized, placebo-controlled trial was conducted on 135 patients undergoing vaginal hysterectomy under spinal anesthesia. The patients were divided in three groups of 45 patients each: group 0, placebo; group 1, 75 mg pregabalin; and group 2, 150 mg pregabalin; each treatment of which was administered one hour before surgery. The Ramsay sedation scale (RSS) was used for pre-operative assessment and the visual analog scale (VAS) was used to determine pain at rest and for cough on the first post-operative day. The time for the requirement of rescue analgesics on the first post-operative day was also assessed. RESULTS: The RSS scores were significantly higher in groups 1 and 2 as compared to the controls (P < 0.001). Postoperative VAS scores for pain both at rest and on cough were significantly reduced in groups 1 and 2 (P < 0.001). Rescue analgesic consumption decreased significantly in groups 1 and 2 (P < 0.001). The time at which rescue analgesia was administered (first dose) was 4.45 hours in group 0, 10.86 hours in group 1, and 16.82 hours in group 2 (P < 0.001). CONCLUSIONS: Pregabalin administered as premedication provided significant postoperative pain relief and decreased the requirement of other parenteral analgesics. Pregabalin doses of 150 mg had a better analgesic profile, but the advantages of their use may be limited by side effects such as dizziness. Thus, it is concluded that pregabalin doses of 75 mg may be the optimal pre-emptive dose.