title: The limited efficacy of tramadol in postoperative patients: a study of ED80 using the continual reassessment method.
abstract: BACKGROUND
  The aim of this study was to reevaluate the efficacy of tramadol for postoperative analgesia and to determine its ED80 (the clinical dose for which 80% of the patients had their pain adequately relieved) using the Continual Reassessment Method. Because the preliminary results of the first 24 patients were contradictory to the literature, we performed a second trial to verify and validate our data.
  
  
  METHODS
  The study was double-blind and prospective. Participants were allocated to a dose of tramadol by 3-patient cohorts, in order of inclusion. The dose of tramadol received in each cohort was determined by the reaction of all previous patients. Five doses were chosen before beginning, with a probability of a positive reaction associated with each: 60 (0.4), 100 (0.55), 140 (0.7), 190 (0.8), and 260 mg (0.9). Tramadol was considered effective if the numeric pain scale was > or = 3/10 at T30.
  
  
  RESULTS
  The effective dose in 80% of patients was 260 mg for both trials. The probability of success of the 260 mg dose was 0.699 (95% credibility interval, 0.471-0.874) and 0.657 (95% credibility interval, 0.437-0.853) for trial 1 and trial 2, respectively.
  
  
  CONCLUSIONS
  Tramadol used as a sole drug cannot be considered the drug of choice after moderately painful surgery. The doses needed to relieve pain in 80% of patients are much larger than the usual dose of 100 mg. The Continual Reassessment Method allowed us to determine the ED80 of tramadol with a limited number of patients.
authors.affiliation: AP-HP, Univ Paris-Sud, Hôpital Bicêtre, Département d'Anesthésie-Réanimation, F-94275, Le Kremlin-Bicêtre, France.
authors.forename: Aude
authors.initials: A
authors.lastname: Thévenin
authors.forename: Hélène
authors.initials: H
authors.lastname: Beloeil
authors.forename: Antonia
authors.initials: A
authors.lastname: Blanie
authors.forename: Dan
authors.initials: D
authors.lastname: Benhamou
authors.forename: Jean-Xavier
authors.initials: JX
authors.lastname: Mazoit
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000187:drug effects* / Q000379:methods*; D010149:Postoperative Pain / Q000188:drug therapy* / Q000378:metabolism; D011446:Prospective Studies; D014147:Tramadol / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D014147:Tramadol