The purpose of this study is to determine whether ATI-7505 is effective in the treatment of chronic idiopathic constipation.

This study is designed to evaluate the safety and efficacy of ATI 7505 in generally healthy, adult patients who have had symptoms of chronic idiopathic constipation for at least 6 months as defined in the ROME III criteria.

Inclusion Criteria:

• written informed consent
• 18 and 75 years of age
• constipation symptom onset at least 6 months ago & meet ROME III criteria for chronic constipation
• negative colonoscopy or air contrast barium enema within the past 2 years if ≥50 years of age or within the past 5 years if <50 years of age;
• are able to refrain from use of medications known to treat constipation or associated symptoms throughout the study

Exclusion Criteria:

• transabdominal surgery, unstable coronary artery disease, organic gastrointestinal disease, collagen vascular disease, or any alarm symptoms within the 6 months prior to screening;
• taking prohibited medications (including laxatives, herbal remedies)
• participating in another drug or medical device study or use of any investigational drug within 30 days before dosing or planning to use prior to study completion;
• QTcB >440 msec, abnormal 12-lead ECG, family history of sudden death at age <40 years or history of long QT syndrome
• alcohol or drug abuse within the 6 months prior to screening;
• autonomic dyssynergic defecation