title: The effects of melatonin premedication on propofol and thiopental induction dose-response curves: a prospective, randomized, double-blind study.
abstract: BACKGROUND
  The effect of melatonin on the intraoperative requirements for i.v.anesthetics has not been documented. We studied the effect of melatonin premedication on the propofol and thiopental dose-response curves for abolition of responses to verbal commands and eyelash stimulation.
  
  
  METHODS
  This prospective, randomized, double-blind study included 200 adults with ASA physical status I. Patients received either 0.2 mg/kg melatonin or a placebo orally for premedication (n = 100 per group). Approximately 50 min later, subgroups of 10 melatonin and 10 placebo patients were administered various doses of propofol (0.5, 1.0, 1.5, 2.0, or 2.4 mg/kg) or thiopental (2.0, 3.0, 4.0, 5.0, or 6.0 mg/kg) for anesthetic induction. The ability of each patient to respond to the command, "open your eyes," and the disappearance of the eyelash reflex were assessed 60 s after the end of the injection of propofol or thiopental. Dose-response curves were determined by probit analysis.
  
  
  RESULTS
  Melatonin premedication decreased thiopental ED50 values for loss of response to verbal command and eyelash reflex from 3.4 mg/kg (95% confidence interval, 3.2-3.5 mg/kg) and 3.7 mg/kg (3.5-3.9 mg/kg) to 2.7 mg/kg (2.6-2.9 mg/kg) and 2.6 mg/kg (2.5-2.7 mg/kg), respectively (P < 0.05). Corresponding propofol ED50 values decreased from 1.5 mg/kg (1.4-1.6 mg/kg) and 1.6 mg/kg (1.5-1.7 mg/kg) to 0.9 mg/kg (0.8-0.96 mg/kg) and 0.9 mg/kg (0.8-0.95 mg/kg), respectively (P < 0.05).
  
  
  CONCLUSIONS
  Melatonin premedication significantly decreased the doses of both propofol and thiopental required to induce anesthesia.
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Texas M.D. Anderson Cancer Center, Unit 409, 1400 Holcombe Boulevard, Houston, TX 77030, USA. naguib@mdanderson.org
authors.forename: Mohamed
authors.initials: M
authors.lastname: Naguib
authors.forename: Abdulhamid H
authors.initials: AH
authors.lastname: Samarkandi
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Moniem
authors.forename: Emad El-Din
authors.initials: Eel-D
authors.lastname: Mansour
authors.forename: Ahmad A
authors.initials: AA
authors.lastname: Alshaer
authors.forename: Hasan A
authors.initials: HA
authors.lastname: Al-Ayyaf
authors.forename: Awatif
authors.initials: A
authors.lastname: Fadin
authors.forename: Saleh W
authors.initials: SW
authors.lastname: Alharby
mesh_terms: D000293:Adolescent; D000328:Adult; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008875:Middle Aged; D011292:Premedication; D015742:Propofol / Q000494:pharmacology*; D011446:Prospective Studies; D011963:Receptors, GABA-A / Q000187:drug effects; D013874:Thiopental / Q000494:pharmacology*
chemical_list: D011963:Receptors, GABA-A; D013874:Thiopental; D008550:Melatonin; D015742:Propofol