Fig. 1

Scatterplot of the change in seizure-like event (SLE) frequency against in vivo hypnotic potency (mg/kg) for ketamine and each of the 21 ketamine analogues. Triangles are the non-ester analogues (including ketamine—circled); stars are the ester analogues. The three agents identified by arrows that were moderately potent hypnotics but did not induce a reduction in SLE frequency were either seizureogenic or had very rapid offset (<100 s)