Common Side Effects and Metabolic Syndrome due to Clozapine: Relationship with the Clinical Variables and Disability

Common side effects of clozapine may affect the treatment process negatively. In this study, we aimed to assess the common side effects and the prevalence of metabolic syndrome in schizophrenia patients treated with clozapine, and to study their relationship with clinical variables and disability.

One hundred and twenty two patients who met DSM-IV criteria for schizophrenia, and were on clozapine treatment were included in the study. Clinical status was evaluated through a clinical interview and review of the medical records, and physical measures and laboratory tests were recorded. Patients were assessed with the Structured Clinical Interview for DSM-IV Axis I Disorders, UKU (Udvalg for Kliniske Undersogelser) Side Effect Rating Scale, World Health Organization (WHO)-Disability Assessment Schedule II, Positive and Negative Syndrome Scale, Global Assessment Scale, Clinical Global Impression Scale.

Common side effects of clozapine were hypersalivation, fatigue, sedation and constipation. The relationship between constipation and clozapine dose, and dizziness and norclozapine plasma levels were significant. The prevalence of metabolic syndrome was 50%, and patients with metabolic syndrome had higher means of age and lifetime cigarette consumption. Disability was positively correlated with the severity of psychopathology and the number of side effects, and negatively correlated with the age at onset of illness. Severity of the psychopathology and the number of side effects predicted the severity of the disability.

Clozapine was associated with various side effects and half of the patients had metabolic syndrome. Assessment of common side effects due to clozapine is important for reducing disability.