Clozapine tolerability in Treatment Resistant Schizophrenia: exploring the role of sex

Clozapine is the only evidence-based drug indicated for Treatment Resistant Schizophrenia but it is largely underprescribed, partially due to its life-threatening adverse effects (AEs). However, clozapine treatment is burdened by other common AEs as constipation, hypersalivation, postural hypotension, tachycardia and metabolic abnormalities. Few studies have investigated sex-related differences in clozapine's tolerability, reporting women to experience more frequently weight gain, hyperglycemia and constipation, while men hypertension and dyslipidemia. Based on these premises, we investigated clinical, psychopathological and metabolic sex-related differences among 147 treatment-resistant patients treated with clozapine, with a specific focus on non-life-threatening AEs. We observed significant higher prevalence of tachycardia in men, and of orthostatic hypotension and constipation in women. Concerning metabolic alterations, we observed significant lower levels of HDL-cholesterol and higher prevalence of hypertriglyceridemia among men, whereas females showed higher prevalence of abdominal obesity. Consistently with previous studies, our data confirm the presence of sex-related differences in clozapine tolerability, with a main effect of sex especially for tachycardia, postural hypotension and constipation. Although non-life-threatening, these common AEs significantly affect patients' quality of life, undermine compliance and cause treatment discontinuation. A better understanding of this topic could contribute to tailor therapeutic approaches, thus improving tolerability, compliance and clinical stability.