“…Several other classes of CNS-acting drugs have been shown to exhibit surface activity, although generally the relationship between surface activity and biological activity has not been well established. Kuffner et al (37) reported the surface tension of a 0.0025 M solution of butylbarbituric acid to be 56 dyneslcm. Lewis (38) reported two short-acting barbiturates, pentobarbital and quinalbarbital, to be surface active, while barbital and phenobarbital, both longer acting compounds, showed little or no surface activity.…”