Inclusion Criteria

• Females
• Age 18 to 65 years
• A diagnosis of functional constipation as defined by two or more of the following
  • Fewer than three spontaneous complete bowel movements per week
  • Hard or lumpy stools more than 25 % of the time
  • Straining during a bowel movement more than 25 % of the time
• A normal rectal exam result on file within the past 2 years or performed at screen to exclude the possibility of an evacuation disorder
  • Examination must exclude findings suggestive of an evacuation disorder such as high sphincter tone at rest, failure of perineal descent and spasm, tenderness or paradoxical contraction of the puborectalis muscles
• Females of child-bearing potential (those who have not experienced a bilateral tubal ligation, hysterectomy or menopause) must use an acceptable method of contraception during the study
  • Acceptable methods are surgical sterilization, hormonal methods such as oral contraceptives, Norplant and Depo-Provera, double barrier method such as a condom and spermicide, and an IUD
  • Abstinent females may participate if they agree to use the double barrier method should they become sexually active during the study
• Able to provide written informed consent prior to any study procedures being performed

Exclusion Criteria

• Pregnant or breast feeding
• Structural or metabolic diseases/conditions that affect the gastrointestinal system or functional gastrointestinal disorders other than constipation
• The long version BDQ will be used to confirm patients have constipation
• Unable to withdraw all medications 48 hours prior to visit 1
• Any medication that alters GI transit including but not limited to
  • Laxatives
  • Magnesium or aluminum-containing antacids
  • Prokinetics
  • Erythromycin
  • Narcotics
  • Anticholinergics
  • Tricyclic antidepressants and SNRIs
  • Analgesic drugs including opiates, NSAIDs, and COX-2 inhibitors 
    • Tylenol is permitted
  • GABAergic agents 
  • Benzodiazepines
• All other concomitant medications will be reviewed on a case by case basis by the study physicians
• Clinical evidence (including but not limited to a clinically significant abnormal physical exam, ECG or laboratory test result in the past medical record) or current clinically significant abnormal physical exam or laboratory test result that could indicate significant cardiovascular, respiratory, renal, hepatic, gastrointestinal, hematological, neurological, psychiatric or other diseases that interfere with the objectives of the study
  • If a laboratory test result is abnormal and clinically significant, it may be repeated once at the discretion of the PI
  • If the laboratory test result remains abnormal and clinically significant, the patient will be discontinued from the study and referred to a primary care physician for further evaluation
• Considered by the PI to be alcoholics not in remission or known substance abusers
• Have participated in another clinical study in the past 30 days