Overview Proof-of-Principle Study of TC-6499 in the Treatment of Constipation Predominant Irritable Bowel Syndrome (IBS) Status: Completed Trial end date: 2010-10-01 Target enrollment: Participant gender: Summary Study is to assess the effectiveness of TC-6499 in the treatment of constipation predominant IBS patients over a 28-day period. Phase: Phase 2 Details Lead Sponsor: Targacept Inc.