The clinical impact of preoperative melatonin on postoperative outcomes in patients undergoing abdominal hysterectomy.
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.
Caumo
Wolnei
W
Anesthesia Service and Perioperative Medicine at Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Brazil.
Torres
Fernanda
F
Moreira
Nívio L
NL
Auzani
Jorge A S
JA
Monteiro
Cristiano A
CA
Londero
Gustavo
G
Ribeiro
Diego F M
DF
Hidalgo
Maria Paz L
MP
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
D008550:Melatonin