Treatment-Resistant Schizophrenia Often Linked to Drug Underuse

A significant portion of supposedly treatment-resistant schizophrenia patients actually have subtherapeutic antipsychotic plasma levels, due either to low adherence or medication underexposure, according to a recent study.

For their study, researchers measured the antipsychotic plasma levels of 99 individuals who were provisionally diagnosed with treatment-resistant schizophrenia, but had not been prescribed clozapine.

​______________________________________________________
RELATED CONTENT
Adjunctive ECT Improves Cognition, Symptoms in Treatment-Resistant Schizophrenia
White Matter Wiring Appears Frayed in People With Schizophrenia
Nearly 80% of Schizophrenia Risk Is Genetic
______________________________________________________

Overall, 35% of patients had subtherapeutic plasma levels. Of these, 34% were undetectable. Characteristics associated with subtherapeutic and undetectable plasma levels were black ethnicity and lower dose. Patients with subtherapeutic and undetectable plasma levels were significantly more likely to be hospitalized than those without.

“A significant proportion of patients considered treatment-resistant have subtherapeutic antipsychotic plasma levels, and this is associated with subsequent admission. The presence of subtherapeutic plasma levels may suggest a need to address adherence or pharmacokinetic factors as opposed to commencing clozapine treatment. While antipsychotic levels are not recommended for the routine adjustment of dosing, they may assist with the assessment of potential treatment resistance in schizophrenia.”

—Michael Potts

Reference:

McCutcheon R, Beck K, D’Ambrosio E, et al. Antipsychotic plasma levels in the assessment of poor treatment response in schizophrenia [published online October 26, 2017]. Acta Psychatr Scand. doi:10.1111/acps.12825.