PMID: 41413Aug 1, 1979

Neuroleptic-potentiating effect of alpha-methyl-p-tyrosine compared with haloperidol and placebo in a double-blind cross-over trial

Acta Psychiatrica Scandinavica
G MagelundD E Casey


The hypothesis that schizophrenia results from overactive dopaminergic influences suggests that reducing dopamine synthesis may increase the clinical effects of dopamine receptor blocking neuroleptic drugs. The neuroleptic potentiating role of alpha-methyl-paratyrosine (AMPT), a tyrosine hydroxylase inhibitor, was compared with haloperidol and placebo in a double-blind cross-over trial. Both AMPT and haloperidol increased the anti-schizophrenic effect of neuroleptic treatment in reduced dose compared with placebo (P less than 0.05), though two patients relapsed during the AMPT period. Both drugs slightly increased extrapyramidal symptoms, but the effect was greater with haloperidol. The limited antipsychotic effect and the potential for aggravating neurological symptoms suggest that the combination of AMPT and neuroleptics does not offer a superior advantage to treating schizophrenia. AMPT, however, may still be used as a research tool in elucidating pathogenetic mechanisms.


Jun 20, 2019·Frontiers in Psychiatry·Davide AmatoAndreas Heinz
Nov 19, 2013·The Cochrane Database of Systematic Reviews·Clive E AdamsStephen Lawrie

Related Concepts

Antipsychotic Effect
Neurologic Manifestations
Assay OF Haloperidol
Extrapyramidal Sign
Antipsychotic Agents
Drug Evaluation
Deficiency of acetyl-CoA Acetyltransferase
Dopamine Receptor

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