The effects of adding long-acting injectable antipsychotic drugs to clozapine on relapse and hospitalization in patients with treatment-resistant schizophrenia: a mirror-image retrospective study

The literature assessing the addition of long-acting injectable antipsychotics (LAIs) to clozapine is limited. The aim of this retrospective study was to determine the safety and effectiveness of adding LAIs to clozapine in patients with treatment-resistant schizophrenia (TRS). Patients aged 18-65 years with TRS, who were treated with first-generation (FGA-LAIs) and second-generation (SGA-LAIs) for at least 1 year after clozapine use, were included retrospectively by registration system scanning. Effectiveness measures included relapses and hospitalizations and days of hospitalization. Safety outcomes included levels of neutrophils, fasting blood sugar, total cholesterol, triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and prolactin. The data of 29 patients who met the study criteria were evaluated. The numbers and days of hospitalizations and the numbers of relapses significantly decreased after LAI addition. Comparisons of the neutrophil counts and the total cholesterol, triglyceride, HDL, LDL, prolactin, and fasting blood glucose levels as safety indicators of the clozapine and LAI combination revealed no statistically significant change in these values before and after LAI addition. Adding LAIs to clozapine is apparently well tolerated in patients with TRS and may have a positive effect on the course of the disease.