title: The clinical impact of preoperative melatonin on postoperative outcomes in patients undergoing abdominal hysterectomy.
abstract: BACKGROUND
  Melatonin has sedative, analgesic, antiinflammatory, antioxidative, and chronobiotic effects. We determined the impact of oral melatonin premedication on anxiolysis, analgesia, and the potency of the rest/activity circadian rhythm.
  
  
  METHODS
  This randomized, double-blind, placebo-controlled study included 33 patients, ASA physical status I-II, undergoing abdominal hysterectomy. Patients were randomly assigned to receive either oral melatonin 5 mg (n = 17) or placebo (n = 16) the night before and 1 h before surgery. The analysis instruments were the Visual Analog Scale, the State-Trait Anxiety Inventory, and the actigraphy.
  
  
  RESULTS
  The number of patients that needed to be treated to prevent one additional patient reporting high postoperative anxiety and moderate to intense pain in the first 24 postoperative hours was 2.53 (95% CI, 1.41-12.22) and 2.20 (95% CI, 1.26-8.58), respectively. The number-needed-to-treat was 3 (95% CI, 1.35-5.0) to prevent high postoperative anxiety in patients with moderate to intense pain, when compared with 7.5 (95% CI, 1.36-infinity) in the absence of pain or mild pain. Also, the treated patients required less morphine by patient-controlled analgesia, as assessed by repeated measures ANOVA (F[1,31] = 6.05, P = 0.02). The rest/activity cycle, assessed by actigraphy, showed that the rhythmicity percentual of 24 h was higher in the intervention group in the first week after discharge ([21.16 +/- 8.90] versus placebo [14.00 +/- 7.10]; [t = -2.41, P = 0.02]).
  
  
  CONCLUSIONS
  This finding suggested that preoperative melatonin produced clinically relevant anxiolytic and analgesic effects, especially in the first 24 postoperative hours. Also, it improved the recovery of the potency of the rest/activity circadian rhythm.
authors.affiliation: Anesthesia Service and Perioperative Medicine at Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Brazil.
authors.forename: Wolnei
authors.initials: W
authors.lastname: Caumo
authors.forename: Fernanda
authors.initials: F
authors.lastname: Torres
authors.forename: Nívio L
authors.initials: NL
authors.lastname: Moreira
authors.forename: Jorge A S
authors.initials: JA
authors.lastname: Auzani
authors.forename: Cristiano A
authors.initials: CA
authors.lastname: Monteiro
authors.forename: Gustavo
authors.initials: G
authors.lastname: Londero
authors.forename: Diego F M
authors.initials: DF
authors.lastname: Ribeiro
authors.forename: Maria Paz L
authors.initials: MP
authors.lastname: Hidalgo
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001007:Anxiety / Q000517:prevention & control / Q000523:psychology; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007044:Hysterectomy / Q000379:methods / Q000523:psychology; D008550:Melatonin / Q000008:administration & dosage*; D008875:Middle Aged; D010147:Pain Measurement / Q000187:drug effects; D010149:Postoperative Pain / Q000517:prevention & control* / Q000523:psychology; D011300:Preoperative Care / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D008550:Melatonin