Clozapine plasma levels and dosing strategies in patients with treatment-refractory schizophrenia

Peter F Buckley, P. Cola, M. Hasegawa, C. Lys, P. Thompson

Research output: Contribution to journalArticle

Abstract

Objective: To determine the effect on clinical response to clozapine of increasing the plasma levels of clozapine and its major metabolite N- desmethylclozapine in 19 patients with schizophrenia who had plasma clozapine levels ≤ 370ng/ml, a level previously determined to identify patients who were unlikely to have an adequate response to clozapine. Method: The dosage of clozapine was increased by 20% in 11 patients and left unaltered in the other eight patients. Clozapine and N-desmethylclozapine plasma levels were measured after six weeks at the higher dose. Results: Nine of the 11 patients in whom clozapine dosage was increased subsequently achieved plasma clozapine levels ≤ 370ng/ml. However, in this group of patients who already had partially responded to clozapine, increasing the dosage of clozapine did not produce additional clinical improvement. Conclusion: Clozapine plasma levels are useful in clinical practice to guide dosage strategies. However, these results suggest that increasing the dosage of clozapine to achieve plasma levels ≤ 370ng/ml is unlikely to produce further improvement in patients who have already achieved a partial response to clozapine at plasma levels ≤ 370ng/ml.

Original languageEnglish (US)
Pages (from-to)85-88
Number of pages4
JournalIrish Journal of Psychological Medicine
Volume14
Issue number3
DOIs
StatePublished - Jan 1 1997

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Clozapine
Schizophrenia
norclozapine
Therapeutics
Plasma

ASJC Scopus subject areas

  • Applied Psychology
  • Psychiatry and Mental health
  • History and Philosophy of Science

Cite this

Clozapine plasma levels and dosing strategies in patients with treatment-refractory schizophrenia. / Buckley, Peter F; Cola, P.; Hasegawa, M.; Lys, C.; Thompson, P.

In: Irish Journal of Psychological Medicine, Vol. 14, No. 3, 01.01.1997, p. 85-88.

Research output: Contribution to journalArticle

Buckley, Peter F ; Cola, P. ; Hasegawa, M. ; Lys, C. ; Thompson, P. / Clozapine plasma levels and dosing strategies in patients with treatment-refractory schizophrenia. In: Irish Journal of Psychological Medicine. 1997 ; Vol. 14, No. 3. pp. 85-88.
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