robalzotan and Abdominal-Pain

To investigate the efficacy and safety of the 5-hydroxytrypamine 1A (5-HT(1A)) receptor antagonist AZD7371 tartrate monohydrate (robalzotan tartrate monohydrate), termed AZD7371 here, in patients with irritable bowel syndrome (IBS).. Patients meeting the Rome II 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.. 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.. In view of the AE profile and lack of efficacy in IBS, the clinical development of AZD7371 has been stopped.

Topics: Abdominal Pain; Administration, Oral; Adolescent; Adult; Aged; Benzopyrans; Dose-Response Relationship, Drug; Double-Blind Method; Female; Follow-Up Studies; Humans; Irritable Bowel Syndrome; Male; Middle Aged; Pain Measurement; Prospective Studies; Quality of Life; Receptor, Serotonin, 5-HT1A; Serotonin 5-HT1 Receptor Antagonists; Surveys and Questionnaires; Treatment Outcome

5-Hydroxytryptamine 1A (5-HT(1A)) receptors have been suggested as a target for the treatment of irritable bowel syndrome (IBS). A recent clinical trial investigating the efficacy of the selective 5-HT(1A) antagonist AZD7371 [3(R)-(N,N-dicyclobutylamino)-8-fluoro-3,4-dihydro-2H-1-benzopyran-5-carboxamide (R,R)-tartrate monohydrate] showed no symptomatic improvement in IBS patients. We characterized the mechanisms mediating potential analgesic effects of AZD7371 in a model of colorectal distension (CRD)-induced visceral pain in rats to understand its mechanism of action and the lack of clinical efficacy. Visceromotor and cardiovascular responses (telemetry) were assessed in conscious rats during noxious CRD (80 mm Hg). Effects of AZD7371 (3-300 nmol/kg i.v.; 1-30 micromol/kg p.o.) and a reference 5-HT(1A) antagonist, WAY-100635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide maleate salt; 3-300 nmol/kg i.v.), were assessed. Effects of intracerebroventricular AZD7371 were also evaluated. Intravenous AZD7371 or WAY-100635 and oral AZD7371 dose-dependently inhibited visceromotor responses to CRD (ED(50), 203, 231, and 14 micromol/kg, respectively). In telemetrized rats, oral AZD7371 inhibited visceromotor responses to CRD without affecting the concomitant hypertensive and tachycardic responses. Intracerebroventricular AZD7371 did not affect visceromotor responses, whereas it inhibited micturition. None of the doses tested induced visible gross side effects. AZD7371, likely acting at a spinal site, inhibited the visceromotor but not the cardiovascular responses to visceral pain in the CRD model in rats. Although agents effective on multiple pain-related readouts in the CRD model (e.g., pregabalin or clonidine) alleviate IBS symptoms, AZD7371, which is effective on only one pain-related pseudoaffective readout, does not. Data from preclinical CRD models of visceral pain need to be interpreted cautiously as it relates to their clinical translational value.

Topics: Abdominal Muscles; Abdominal Pain; Animals; Benzopyrans; Blood Pressure; Cardiovascular Physiological Phenomena; Colonic Diseases; Dilatation, Pathologic; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Heart Rate; Piperazines; Pyridines; Rats; Rats, Sprague-Dawley; Serotonin 5-HT1 Receptor Antagonists; Serotonin Antagonists; Urination