Effect of Lubiprostone on Methanogenesis and Bowel Function in Chronic Constipation.

Inclusion Criteria:

- Constipation as defined by Rome III criteria13. Patients must have symptoms > 3
days/month for the past three months and report at least two of the following symptoms
≥ 25% of the time: straining, lumpy or hard stool, sensation of incomplete evacuation,
sensation of anorectal obstruction/blockage, use of manual maneuvers, < 3 bowel
movements/week. Also,they should have insufficient criteria for IBS, and only rarely
loose stools without the use of laxatives.

- ≥ 3 ppm methane value at baseline1, 2(before sugar load).

Exclusion Criteria:

- Patients taking drugs that are known to be constipating will be excluded or asked to
discontinue medications for at least 2 weeks and reassessed. For example, we will
recommend that patients taking calcium channel antagonists contact their respective
primary care physicians to explore alternative medications for hypertension such as
beta blockers or ACE-inhibitors. If the calcium channel antagonists are able to be
discontinued, patients will be re-screened at least two weeks after the medications
are discontinued. If patients no longer meet inclusion criteria, they will be excluded
from the study. Patients who remain constipated will be eligible for enrollment.

- Patients with co-morbid illnesses such as severe cardiovascular disease, chronic renal
failure, or those with previous gastrointestinal surgery except cholecystectomy and
appendectomy

- Patients with neurologic diseases such as multiple sclerosis, strokes, spinal cord
injuries, and those who have problems with cognizance, i.e. a mini-mental score of <15
and/or are legally blind will be excluded.

- Women who are pregnant or are likely to conceive during the course of the study will
be excluded. Urinary pregnancy tests will be performed on all women of child-bearing
potential prior to enrollment and before any x-ray of the abdomen.

- Patients with Hirschsprung' s disease, or active local anorectal problems such as anal
fissures, bleeding hemorrhoids, Crohn's, colitis, or colon cancer.

- Patients with alternating constipation and diarrhea and those who fulfill the Rome-III
criteria for irritable bowel syndrome.

- Recent antibiotic use (last 6 weeks).

- Patients using laxatives, PEG or Tegaserod and unwilling to discontinue these
medications at least 2 weeks prior to the study.