The novel drug tegaserod, which is an agonist of the serotonin type 4 receptor, shows promise as the first treatment option for patients with mixed pattern irritable bowel syndrome, according to a presentation at the annual Digestive Disease Week.

Based on Rome II criteria, patients with irritable bowel syndrome (IBS) are classified based on their primary bowel complaint as either syndrome with Constipation (IBS-C) or syndrome with Diarrhea (IBS-D). Patients who do not fulfill standards for either type can exhibit a mixed bowel pattern (IBS-M). A recent study of patients published in Gastroenterology revealed that nearly one third of participants experienced had mixed pattern disease.

"IBS patients who suffer with a mixed bowel pattern are in need of an effective treatment option," said William Chey, MD, Associate Professor of Medicine and Director of the GI Physiology Laboratory at the University of Michigan Health System. "These study results are promising as Zelnorm (tegaserod) was shown to provide a statistically significant improvement in satisfactory relief of IBS symptoms in both the IBS-C and IBS-M groups. More than 50 percent of the IBS-M patients experienced a response to tegaserod."

Zelnorm is the first and only prescription medication approved by the U.S. Food and Drug Administration (FDA) for both Chronic Idiopathic Constipation and irritable bowel syndrome with Constipation.

The randomized, double-blind, placebo-controlled, multicenter study evaluated 661 women with IBS-C (337) or IBS-M (324). Study participants were asked to provide an assessment of satisfactory relief over four weeks of treatment with 6 mg tegaserod twice daily or placebo.

Other endpoints were the proportion of patients reporting satisfactory relief for greater than or equal to 3 of 4 treatment weeks (75% rule) and improvement during each of the 4 weeks in individual symptoms. Baseline symptom assessment clearly distinguished between IBS-C and IBS-M cohorts.

Overall, tegaserod provided statistically significant improvement in satisfactory relief of symptoms over a four-week treatment for both patient cohorts. In the two cohorts, the percentage of patients experiencing satisfactory relief of symptoms was significantly higher for tegaserod compared with placebo (constipation: 43.3 percent versus 28.9 percent; mixed pattern: 52.3 percent versus 36.3 percent). Tegaserod was significantly superior to placebo at improving weekly bowel movement frequency, stool consistency and straining.

The most frequent adverse events were diarrhea, headache, abdominal pain, and nausea. However, adverse event discontinuations were low for both tegaserod and placebo groups (constipation: 1.2 percent versus 2.4 percent and mixed: 2.5 percent vs. 3.6 percent). There were no cases of diarrhea with clinically significant consequences such as need for hospitalization, need for intravenous fluids, or presence of abnormal lab values.