Comparative depression of several short acting barbiturates and spiro-barbiturates.

In an effort to develop new and possibly better types of barbiturates, suitable for intravenous use, a large number of spiro-barbiturates have been prepared by a ring closure on the 5-carbon atom of the barbituric acid and afforded for pharmacologic study. Spiro(2'-ethyl-3',5'-dimethyl cyclopentane) thio-barbituric acid appears to be the most promising product of a series of 50 analogues. Stoelting et al.(1) reported the anesthetic and hypnotic proper ties of this compound in laboratory animals and the satisfactory clinical appli cation for anesthesia in fifty patients. The present report (2) deals with the study of the duration of depression of this new spiro-thiobarbituric acid and its non-thioanalogue**. For the purpose of brevity, spiro-thiobarbiturate and spiro-barbiturate will be used in this report instead of the long chemical name. The comparative results of depression of these new compounds and a well known short acting barbiturate seemed necessary and of interest. Pentobarbital and its thio-analogue, thiopental, are well known barbiturates, thus should serve admirably as a standard by which to judge the new barbiturates. Secobarbital and its thio-analogue, surital (thioamytal), are also included in this comparative study because of their similar depressive potency in the pentobarbital series.