Fig. 1.

Time course of analgesic effects in rats treated with tramadol. The rats (n=6) were intraperitoneally administered saline, and tramadol 5, 10, 20 and 40 mg/kg, respectively (group 'Control', 'TRA5', 'TRA10', 'TRA20' and 'TRA40'). Analgesic effects were evaluated with 50℃ hot-water tail-flick latency, and were expressed as a percentage of maximal possible effect (%MPE). Data were expressed as mean±S.D. Data were analyzed by two factor repeated measures ANOVA with time and treatment, and a Bonferroni test was used to analyze variables for time between groups. ^*p<0.05 when compared to Control group, ^#p<0.05 when compared to TRA5 group, ⁺p<0.05 when compared to TRA10 group, and ^@p<0.05 when compared to TRA20 group.