STUDIES ON BARBITURATES XIII. ANALYSIS OF THE DURATION OF ACTION OF BARBITURATES

¹ From the Department of Pharmacology and Materia Medica, Georgetown University, School of Medicine, Washington, D. C.

The barbiturate content of the brain is usually higher following pentobarbital-sodium, but lower following barbital-sodium or phenobarbital-sodium administration than that of other tissues. The barbiturate concentration in the medulla is relatively higher than in other parts of the brain following pentobarbital, but lower following barbital or phenobarbital administration. These two facts suggest an explanation for the differences in the onset of action and in the acute toxicity that exist between the long and the short acting barbiturates. Long acting barbiturates are destroyed slowly in the body and their presence in the brain persists for long periods, whereas pentobarbital is quickly destroyed and rapidly disappears from the central nervous system. This fact explains the brief duration of action of this latter barbiturate.