EVIDENCE THAT METHADONE BLOCKS DOPAMINE RECEPTORS IN THE BRAIN

Abstract

Abstract— This study has shown that methadone shares with phenothiazine and butyro‐phenoneneuroleptics several pharmacological and biochemical actions:thus, D,L‐methadone causes catalepsy and hypothermia, blocks apomorphine‐induced gnawing, increases brain homovanillic acid levels and stimulates brain dopamine synthesis. The dextro isomer of methadone is inactive. α‐Methyl‐tyrosine potentiates and apomorphine reverses methadone‐induced catalepsy. The data suggest that methadone, like butyrophenone and phenothiazine neuroleptics, blocks dopamine receptors in brain.