An Open-Label, Head to Head Comparison Study between Prucalopride and Lactulose for Clozapine Induced Constipation in Patients with Treatment Resistant Schizophrenia

Clozapine remains as the gold standard for the management of treatment resistant schizophrenia. Nevertheless, mortality and morbidity associated with Clozapine is partly contributed by its adverse effect of constipation in view of its prominent anticholinergic properties. Despite the evidence that approximately 60% of patients on Clozapine will experience constipation, there is no proper guideline as to the best laxative in the treatment of Clozapine induced constipation. Hence this study was conducted to evaluate the efficacy and safety of Prucalopride and Lactulose in the treatment of Clozapine induced constipation. This was a four week, prospective, open-label head to head comparison study between Prucalopride and Lactulose in the treatment of Clozapine induced constipation. Male and female patients on Clozapine between the age of 18-60 with an established diagnosis of treatment resistant schizophrenia with ≤2 spontaneous complete bowel movement per week were recruited in this study. Eligible patients were assigned into two groups. Patients received Prucalopride 2 mg once daily or Lactulose 10 g once daily for four weeks. Efficacy was analyzed in 58 patients. The proportion of patient with ≥3 spontaneous complete bowel movement (SCBM) was higher in the Prucalopride 2 mg group, reaching significance at Week 4 with p-value of (p = 0.029). The proportion of patient with ≥3 SCBM at Week 1 was 71.4% in the Prucalopride 2 mg group and 60% in the Lactulose 10 g group. The proportion of patient with ≥3 SCBM at Week 4 was 85.7% in the Prucalopride 2 mg group and the proportion remained at 60% in the Lactulose 10 g group. The improvement in the dissatisfaction and treatment satisfaction subscales of the patient assessment of constipation-quality of life (PAC-QOL) were higher in the Prucalopride 2 mg group compared to the Lactulose 10 g group. The common adverse events associated with Prucalopride 2 mg were abdominal pain and loose stools which was transient and subsided within a few days. Over four weeks, in this population of patients with Clozapine induced constipation, Prucalopride 2 mg significantly improved the bowel movement and it was safe.