Outcomes in treatment-resistant schizophrenia: symptoms, function and clozapine plasma concentrations

Autor: Amir Krivoy, Eromona Whiskey, Henrietta Webb-Wilson, Dan Joyce, Derek K. Tracy, Fiona Gaughran, James H. MacCabe, Sukhwinder S. Shergill
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Therapeutic Advances in Psychopharmacology, Vol 11 (2021)
Druh dokumentu: article
ISSN: 2045-1261
20451253
DOI: 10.1177/20451253211037179
Popis: Background: Clozapine is the only medication licenced for treating patients with treatment-refractory schizophrenia. However, there are no evidence-based guidelines as to the optimal plasma level of clozapine to aim for, and their association with clinical and functional outcome. Objective: We assessed the relationship between clinical and functional outcome measures and blood concentrations of clozapine among patients with treatment-refractory psychosis. Methods: Data were reviewed in 82 patients with treatment-refractory psychosis admitted to a specialised tertiary-level service and treated with clozapine. Analysis focussed on the relationship between clozapine and norclozapine plasma concentrations and the patient’s clinical symptoms and functional status. Results: Clinical symptom improvement was positively correlated with norclozapine plasma concentrations and inversely correlated with clozapine to norclozapine plasma concentrations ratio. Clozapine concentrations showed a bimodal association with clinical improvement (peaks around 350 and 660 ng/ml). Clinical symptom improvement correlated with functional outcomes, although there was no significant correlation between the latter and clozapine or norclozapine plasma concentrations. Conclusion: Clozapine treatment was associated with optimal clinical improvement at two different peak plasma concentrations around 350 and 650 ng/ml. Clinical improvement was associated with functional outcome; however, functionality was not directly associated with clozapine concentrations. A subset of patients may require higher clozapine plasma concentrations to achieve clinical improvement.
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