Higher serum concentrations of tyrosine and glutamate in schizophrenia patients treated with clozapine, compared to in those treated with conventional antipsychotics.

Abstract

RATIONALE:

The effect of long-term treatment with the atypical antipsychotic clozapine on the serum amino acid profile in schizophrenia patients has not previously been studied.

OBJECTIVES:

The aim of this study was to compare serum amino acid patterns in patients on long-term clozapine treatment with long-term conventional antipsychotic treatment, and their relationships to insulin resistance and antipsychotic serum concentrations.

METHODS:

Thirty-three patients with schizophrenia or schizoaffective disorder on long-term treatment (mean 8.3 years) with clozapine (n=20) or conventional antipsychotics (n=13) were studied. Amino acids were quantified in fasting serum samples by ion exchange chromatography and markers of insulin resistance and antipsychotic drug concentrations were determined by standard methods.

RESULTS:

Several amino acids, most notably tyrosine and glutamic acid, were elevated above the reference range in several patients receiving clozapine. Additionally, significantly higher mean values of tyrosine (1.5-fold, p=0.001), glutamic acid (2-fold, p=0.0005) and six other amino acids were observed in the clozapine group than in the conventional antipsychotic group. Several amino acids were related to insulin resistance in both treatment groups.

CONCLUSIONS:

In this study, we show that serum tyrosine and glutamic acid concentrations are markedly elevated in patients on long-term clozapine treatment, compared to patients on long-term conventional antipsychotic treatment. These findings are of importance since these two amino acids have been implicated in the pathophysiology of schizophrenia.

• Authors: Kristina Melkersson, Moira Lewitt, Kerstin Hall
• Journal: Neuro endocrinology letters (Neuro Endocrinol Lett) Vol. 36 Issue 5 Pg. 465-80 ( 2015) ISSN: 0172-780X [Print] Sweden
• PMID: 26707048 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amino Acids
• Antipsychotic Agents
• Glutamic Acid
• Tyrosine
• Clopenthixol
• Perphenazine
• Clozapine
• Haloperidol
• Thioridazine

Topics

• Adult
• Amino Acids (blood)
• Antipsychotic Agents (therapeutic use)
• Chromatography, Ion Exchange
• Clopenthixol (therapeutic use)
• Clozapine (therapeutic use)
• Cohort Studies
• Female
• Glutamic Acid (blood)
• Haloperidol (therapeutic use)
• Humans
• Insulin Resistance
• Male
• Middle Aged
• Perphenazine (therapeutic use)
• Prospective Studies
• Psychotic Disorders (drug therapy)
• Schizophrenia (blood, drug therapy)
• Thioridazine (therapeutic use)
• Tyrosine (blood)