Is Preemptive Oral Tizanidine Effective on Postoperative Pain Intensity after Bimaxillary Orthognathic Surgery? A Triple-Blind Randomized Clinical Trial

BACKGROUND: We aimed to investigate the effect of preoperative administration of oral tizanidine on postoperative pain intensity after bimaxillary orthognathic surgery. METHODS: All healthy skeletal class III patients who were candidates for bimaxillary orthognathic surgery were enrolled in this triple-blind randomized clinical trial. The study was carried out in the Maxillofacial Surgery Department of Qaem Hospital, Mashhad, Iran; from January 2021 to November 2021. The consecutive patients were randomly divided into tizanidine and placebo groups. One hour prior to anesthesia induction, the tizanidine group received 4 mg Tizanidine dissolved in 10 ml apple juice, whereas the placebo group received an identical glass of plain apple juice. All operations were performed by the same surgical team, under the same general anesthesia protocol. Postoperative pain was measured using the Visual Analogue Scale (VAS) at 3, 6, 12, 18, and 24 hours. For statistical analysis; the significance level was set at 0.05 using SPSS 23. RESULTS: A total of 60 consecutive patients, consisting of 36 females (60%) and 24 males (40%) with an average age of 25.4 ± 6.0 were recruited. An increasing trend was noticed in the amount of perceived postoperative pain from the 3(rd) till 12(th) hour, and then decreased afterward. Nevertheless, the average amount of pain was significantly lower in the tizanidine compared to the placebo group, in all the evaluated time intervals (P<0.001). Moreover, there was a significantly higher requirement for postoperative opioid analgesics in the placebo compared to the tizanidine group (P=0.011). CONCLUSION: The addition of oral tizanidine was effective in reducing postoperative pain following bimaxillary orthognathic surgery. Further studies are necessary for more relevancy.