Patients requiring opioids for post-operative pain control following elective orthopedic procedures which has resulted in constipation symptoms, and who are in inpatient rehabilitation will be randomized to two different treatment arms: lubiprostone or senna. Baseline scores regarding constipation and a quality of life bowel questionnaire will be compared the day following 6 days of treatment intervention.

The purpose of this study is to assess the efficacy of Lubiprostone (Amitiza) compared to standard care for the treatment of constipation in orthopedic patients receiving opioids for pain control during inpatient rehabilitation. Lubiprostone (Amitiza®) is a locally acting chloride channel activator that increases intestinal fluid, and thus increases intestinal motility. It has been approved for chronic constipation, but not in the setting of opioid-induced constipation. Senna is a stimulant laxative that increases propulsive peristaltic activity of the colon through local effects on the mucosa.

Subjects will be compared using from the Patient Assessment of Constipation (PAC) which has previously been found to be a valid and reliable way to measure constipation symptoms and clinical course. (Frank, Kleinman et al. 1999) as well as with other measures of bowel-related symptoms and functional outcomes.

Inclusion Criteria:

1. Adult, 18 years old or greater.

2. The patient is able to provide informed consent.

3. Anticipated duration of hospitalization of at least 7 days.

4. Woman of childbearing potential must have a negative serum pregnancy test at enrollment. Exclusions for testing include two years or greater postmenopausal, hysterectomy or tubal ligation.

5. Use of opioid for post-op analgesia following orthopedic surgical procedures as defined as IV, IM, transdermal or PO opioid received within the prior 24 hours of hospitalization for pain control, and expectation that an opioid will be continued for pain control.

   • Medication may be administered on a PRN (as needed) basis or scheduled basis
   • One or greater doses has been received within the 24 hours prior to enrollment as determined by medication administration recorded from the acute care facility or RIC MAR.

6. At least one associated symptom of constipation at the time of admission, such as, but not limited to:

   • Lumpy or Hard stools
   • Feeling of incomplete evacuation of bowels
   • Abdominal cramping or pain
   • Straining with movement of bowels or painful bowel movement effort
   • Need for manual assistance to have a bowel movement

Exclusion Criteria:

1. Known allergy or sensitivity to the study medications

2. Females who are pregnant

3. Diarrhea on the day of admission

4. Diagnosis of Clostridium difficile infection during the current hospitalization

5. Pre-existing medical condition or surgical procedure, which is known to commonly lead to bowel dysfunction such as, but not limited to:

   • Crohn's disease
   • Ulcerative colitis
   • Multiple sclerosis
   • Cerebral palsy
   • Spinal Cord Injury
   • Colectomy
   • Malabsorption Syndrome
   • Irritable Bowel Syndrome
   • Abdominopelvic neoplasm (gastric, colon cancer)
   • Severe liver disease
   • Colonic or ileo-colonic resections

Additional laxatives were frequently required for symptom control