Luis E. Rosas-Luna, Anesthesiology Service, Hospital General Ticomán, Mexico City, Mexico Osvaldo D. Castelán-Martínez, Clinical Pharmacology Laboratory, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, Mexico Ignacio Mora-Magaña, Educational Evaluation and Programming Department, Instituto Nacional de Pediatría, Mexico City, Mexico Manuel Ángeles-Castellanos, Anatomy Department, Facultad de Medicina, Universidad Nacional Autónoma de México. Mexico City, Mexico Laura M. Ubaldo-Reyes, Anatomy Department, Facultad de Medicina, Universidad Nacional Autónoma de México. Mexico City, Mexico

Introduction: Midazolam is a benzodiazepine used for sedation, however, can cause respiratory depression and increases morbidity in patients. Melatonin is an effective alternative to manage anxiety in the perioperative period and could help to reduce the use of benzodiazepines during surgery. The aim of this clinical trial was to determine the efficacy of pre-operative sedation with a single-dose melatonin to reduce intraoperative use of midazolam in women under total abdominal hysterectomy (TAH). Materials and methods: This is a double-blind randomized clinical trial conducted in women over 25 years, scheduled for TAH, with American Society of Anesthesiologists Grade I or II. Each patient was randomly assigned to receive 5 mg of melatonin prolonged-release oral capsules or placebo. Midazolam use for anesthetic management was the decision of the treating anesthesiologist and sedation status was determined using the observer’s assessment of alertness/sedation scale. Results: In patients receiving melatonin, the use of midazolam during surgery was less than in patients receiving placebo. In addition, melatonin produces sedation 30 min after administration, the sedative effect was maintained at 60- and 90-min. Furthermore, hospital stay was shorter in patients who received melatonin (p = 0.006). Conclusion: Melatonin is effective for reduces intraoperative midazolam consumption and hospital stay in women undergoing TAH.

Keywords: Perioperative. Hysterectomy. Sedation. Melatonin.