title: Assessment of oral S+ ketamine associated with morphine for the treatment of oncologic pain.
abstract: OBJECTIVE
  Morphine is used frequently to treat oncologic pain. However, tolerance may develop with prolonged use. The association of a NMDA receptor antagonist may reduce or delay the onset of tolerance. S(+) ketamine seems to be more potent and with fewer side effects. The aim of this study was to evaluate the association of S(+) ketamine and morphine in the treatment of oncologic pain.
  
  
  METHODS
  Thirty patients, randomly divided in two groups, participated in this double-blind study. Patients in G1 received 10 mg of morphine PO every 6 hours and 10 mg of S(+) ketamine PO every 8 hours. Patients in G2 received 10 mg of morphine PO every 6 hours and placebo PO every 8 hours. The dose of morphine was adjusted by 5 mg increments whenever necessary. Pain severity was evaluated through a verbal scale.
  
  
  RESULTS
  The percentage of no pain and mild pain was similar in both groups (G1 = 0 and G2 = 0 at M0; G1 = 22.2 and G2 = 53.8 at M1; G1 = 22.2 and G2 = 61.5 at M2; G1 = 44.6 and G2 = 61.5 at M3; and G1 = 44.5 and G2 = 53.8 at M4); Chi-square test. The percentage of moderate relief and complete relief was similar in both groups (G1 = 33.4 and G2 = 53.9 after one week; G1 = 44.4 and G2 = 69.2 after two weeks; G1 = 66.6 and G2 = 69.2 after three weeks; and G1 = 55.6 and G2 = 53.9 after four weeks); Chi-square test. The need to increase the dose of morphine was also similar in both groups (G1 = 2.22 and G2 = 2.15); Mann-Whitney test.
  
  
  CONCLUSIONS
  We did not observe an increase on the analgesic effects of morphine with the association of 10 mg of S(+) ketamine PO in the treatment of oncologic pain.
authors.affiliation: Cristália Produtos Químicos e Farmacêuticos Ltda.
authors.forename: Pedro
authors.initials: P
authors.lastname: Ishizuka
authors.forename: João Batista Santos
authors.initials: JB
authors.lastname: Garcia
authors.forename: Rioko Kimiko
authors.initials: RK
authors.lastname: Sakata
authors.forename: Adriana Machado
authors.initials: AM
authors.lastname: Issy
authors.forename: Sílvia Letícia
authors.initials: SL
authors.lastname: Mülich