Non-CNS Acting Opiates Bearing Guanidino Substituents

Abstract

A series of guanidino-substituted opiates based on morphine, diprenorphine, and buprenorphine have been synthesized. Guanidines with aryl and alkyl substituents as well as unsubstituted ones have been attached to the opiate nucleus with spacer units of varying length. The spacer groups have mainly been attached to the opiates via the opiate nitrogen atom. A few compounds involving attachment through opiate oxygen atoms have been prepared, but were found to be ineffective as analgesics.

The activity of the compounds as analgesics has been evaluated using the phenylquinone (PQ) abdominal-constriction test and their ability to enter the CNS evaluated with the Straub tail response. The compounds most active in the PQ abdominal-constriction test and showing no Straub tail behaviour contained aryl-substituted guanidines.