THE ABSORPTION AND METABOLISM OF ANILERIDINE, ETHYL-1-(4-AMINOPHENETHYL)-4-PHENYLISONIPECOTATE

¹ Merck Institute for Therapeutic Research, Rahway, New Jersey

Anileridine, 1-(4-aminophenethyl)-4-phenylisonipecotate, was rapidly taken up by the tissues of rats following parenteral administration. Highest concentrations of the drug were found in the lungs, kidneys and brain. Concentrations of anileridine in rat brain bear a linear relationship to degree of analgesia.

Anileridine is acetylated in the rat and guinea pig, probably in the liver, possibly also in the lungs, to produce another analgesic, acetyl anileridine. This derivative was found in rat liver, kidneys and lungs in concentrations greater than that of anileridine after administration of the unacetylated compound. It appeared in the brain in smaller amounts.

The metabolism of anileridine resembles that of meperidine in that the major pathways involve saponification and destruction of the isonipecotic acid moiety. Acetylation of the aromatic amino group in anileridine is a major pathway in rats and guinea pigs, but is of minor importance in man.