Randomized, Double-Blind, Placebo-Controlled Trial of the 5-HT1A Receptor Antagonist AZD7371 Tartrate Monohydrate (Robalzotan Tartrate Monohydrate) in Patients With Irritable Bowel Syndrome

OBJECTIVES: To investigate the efficacy and safety of the 5-hydroxytrypamine 1A (5-HT1A) receptor antagonist AZD7371 tartrate monohydrate (robalzotan tartrate monohydrate), termed AZD7371 here, in patients with irritable bowel syndrome (IBS). METHODS: Patients meeting the Rome 11 criteria for IBS (N = 402) were randomized to treatment with AZD7371 20 mg or 5 mg or matching placebo tablets twice daily for 12 wk. The patients completed daily and weekly diary assessments, reporting abdominal discomfort or pain and description of bowel movements. They also completed validated symptom and quality-of-life questionnaires. RESULTS: Neither AZD7371 regimen was significantly more effective than placebo in providing adequate relief from IBS symptoms in at least 2 out of 4 wk per month over the 12 wk of treatment. There was also no significant difference between the treatment groups and placebo in the change in score in the validated symptom and quality-of-life questionnaires. Overall, 22.1% of patients experienced adverse events (AEs) attributed to the study medication: 44 of 133 (33.1%) in the 20 mg AZD7371 group, 27 of 131 (20.6%) in the 5 mg AZD7371 group, and :17 of 134 (12.7%) in the placebo group. Also, 31 of 57 (54%) of AEs leading to discontinuation were central nervous system-related. Hallucinations or hallucination-like AEs were reported by eight patients taking AZD7371, and by none of the patients in the placebo group. After these events led to discontinuation in six patients, the study was prematurely terminated. CONCLUSIONS: In view of the AE profile and lack of efficacy in IBS, the clinical development of AZD7371 has been stopped.