title: [Ketamine and preemptive analgesia.].
abstract: BACKAGROUND AND OBJECTIVES: Since the finding that ketamine blocks NMDA receptors in the neurons of spinal dorsal horn, it has been used to inhibit or decrease central sensitization triggered by nociceptive stimulations. This study aimed at presenting pharmacological aspects of racemic ketamine and its levogyrous compound, as well as its usefulness for preemptive analgesia.
  
  
  BACKGROUND
  Current preemptive analgesia concepts, pharmacological aspects of ketamine and its levogyrous compound, as well as experimental and clinical trials on ketamine and its use in preemptive analgesia are presented.
  
  
  CONCLUSIONS
  The efficacy of ketamine in inhibiting or decreasing central sensitization triggered by nociceptive stimulations is not totally confirmed, probably due to different study and statistical analysis methods.
authors.affiliation: Escola Paulista de Medicina, Universidade Federal de São Paulo.
authors.forename: Caio Márcio Barros de
authors.initials: CM
authors.lastname: Oliveira
authors.forename: Rioko Kimiko
authors.initials: RK
authors.lastname: Sakata
authors.forename: Adriana Machado
authors.initials: AM
authors.lastname: Issy
authors.forename: João Batista Santos
authors.initials: JB
authors.lastname: Garcia