Abstract

The contentand distribution of various analgetic drugs have been determined in the brains of mice, rats, cats, dogs and monkeys at several times after administration. No significant localization of salicylates or of N-acetyl-p-aminophenol has been detected in any portion of the brain. In all species studied, the pituitary glands show a 2-to 3-fold greater concentration than is found in the brain throughout the time period studied. Acetylsalicylate administration to animals leads to the recovery in brain of free salicylate only, in concentrations corresponding to those after salicylate administration. N-acetyl p-aminophenol and salicylamide penetrate the brain to a somewhat greater extent than does the salicylate ion.