Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Constipation is due to the
slow transport (transit) of intestinal contents through the intestines,
primarily the colon. This slow transit may be due to either abnormal function of
the muscles of the entire colon or just the muscles of the anus and rectum.
The treatment of constipation in IBS usually begins with a trial of the
supplements and medications that are used to treat constipation of any cause. In
2002, the FDA approved tegaserod (Zelnorm),
the first drug designed specifically for the treatment of abdominal pain and constipation
in women with IBS. However, in March of 2007, the FDA asked Novartis to suspend sales of tegaserod (Zelnorm) in the United
States because a retrospective analysis of data by Novartis from more than
18,000 patients showed a slight increase in the incidence of cardiovascular
events (heart attacks, strokes and angina) among patients on Zelnorm compared to
placebo. The data showed that cardiovascular events occurred in 13 out of 11,614
patients treated with Zelnorm (0.11%), compared to one cardiovascular event in
7,031 (0.01%) placebo-treated patients. However, it is unclear whether Zelnorm
actually causes heart attacks and strokes. Doctors and scientists will be
scrutinizing the data further to determine the long-term safety of Zelnorm.
The mechanism whereby
tegaserod reduces constipation is interesting. It is the contractions of the
intestinal muscles that controls transit of food through the
intestine. More contractions speed transit, fewer contractions slow transit. In
constipated patients, contractions are fewer. One important chemical in the
control of the contractions is serotonin. Serotonin is manufactured
by the nerves in the intestine. It is released by the nerves and then travels to
other nerves where it binds to receptors on the nerves. It is, in scientific
terms, a "neurotransmitter" that allows nerves to communicate with each other.
When it binds to receptors on nerves that control the contractions of intestinal
muscles, serotonin can either promote or prevent contractions depending on the
type of receptor it binds to. Binding to some types of receptors causes
contractions, and binding to other types of receptors prevents contractions. The
serotonin 5-HT4 receptor prevents contractions when serotonin
binds to it. Tegaserod blocks the 5-HT4 receptor, prevents serotonin from
binding to it, and thereby increases contractions of the intestinal muscles. The
increased contractions speed the transit of intestinal contents. In addition,
tegaserod reduces the sensitivity of the intestinal pain-sensing nerves and can
thereby reduce the perception of pain.
In a randomized, double blind, placebo-controlled study involving more than
1000 patients (80% women) with constipation-predominant IBS, tegaserod was found
to be more effective than placebo in increasing the frequency of stools,
relieving abdominal pain and discomfort, and decreasing the sensation of
bloating in women. (There were an insufficient number of men in the study to
draw conclusions about the effectiveness of treatment in men.) The beneficial
effects of treatment started during the first week of treatment and were
sustained throughout the 12-week period of study.
Diarrhea was the only side effect in the tegaserod study. Diarrhea usually
occurred early during treatment and resolved quickly even if the treatment was
continued. There was no effect of tegaserod on blood counts, liver and kidney
tests, electrocardiograms, blood pressure, pulse, and body weight. (A medication
similar to tegaserod, called cisapride
[Propulsid], which also promoted intestinal muscle contractions,
was withdrawn from the market due to rare but potentially fatal effects on the
electrical rhythm of the heart. So far, there have been no reports of rhythm
disturbances related to tegaserod.) Patients with major liver or kidney disease
should not take tegaserod. The safety of tegaserod in a fetus or
nursing
infants has not been studied and is unknown. Therefore,
pregnant or nursing
women should avoid tegaserod.
Abdominal pain is pain in the belly and can be acute or chronic. Causes include inflammation, distention of an organ, and loss of the blood supply to an organ. Abdominal pain can reflect a major problem with one of the organs in the abdomen such as the appendix, gallbladder, large and small intestine, pancreas, liver, colon, duodenum, and spleen.
Diarrhea is a change is the frequency and looseness of bowel movements. Cramping, abdominal pain, and the sensation of rectal urgency are all symptoms of diarrhea. Absorbents and anti-motility medications are used to treat diarrhea.
Gas or "intestinal gas" means different things to different people. Everyone has gas and eliminates it by belching or farting (passing it through the rectum).
Constipation is defined medically as fewer than three stools per week and severe constipation as less than one stool per week. Constipation usually is caused by the slow movement of stool through the colon. There are many causes of constipation including medications, poor bowel habits, low fiber diets, abuse of laxatives, hormonal disorders, and diseases primarily of other parts of the body that also affect the colon.
Fibromyalgia, formerly
known as fibrositis, causes chronic pain, stiffness, and
tenderness of muscles, tendons, and joints without detectable inflammation. Fibromyalgia patients have an unusually low pain threshold. Symptoms of fibromyalgia include fatigue, abnormal sleep, mental/emotional disturbances, abdominal pain, migraine and tension headaches, and irritable bladder. Treatment of fibromyalgia involves patient education, medication, exercise, and stress reduction.
In lactose intolerance, the digestive system cannot digest lactose (the main sugar in milk). Symptoms of lactose intolerance include diarrhea, flatulence, abdominal pain, abdominal bloating, abdominal distention, and nausea. There are several tests to diagnose lactose intolerance. Treatment is generally made with dietary changes, supplements, and adaptation to small amounts of milk.
Small intestinal bacterial overgrowth (SIBO) refers to a condition in which abnormally large numbers of bacteria (at least 100,000 bacteria per ml of fluid) are present in the small intestine and the types of bacteria in the small intestine resemble more the bacteria of the colon than the small intestine. There are many conditions associated with small intestinal bacterial overgrowth, to include: diabetes, scleroderma, Crohn's disease, and others. There is a striking similarity between the symptoms of irritable bowel syndrome and SIBO. It has been theorized that SIBO may be responsible for the symptoms of at least some patients with irritable bowel syndrome. Symptoms of SIBO include: excess gas, abdominal bloating, diarrhea, and abdominal pain.
Dyspepsia (indigestion) is a functional disease in which the gastrointestinal organs, primarily the stomach and first part of the small intestine, function abnormally. It is a chronic disease in which the symptoms fluctuate infrequency and intensity. Symptoms of dyspepsia include upper abdominal pain, belching, nausea, vomiting, abdominal bloating, early satiety, and abdominal distention (swelling). These symptoms are most often provoked by eating.
Digestion is the complex process of turning food you eat into the energy you need to survive. The digestive process also involves creating waste to be eliminated, and is made of a series of muscles that coordinate the movement of food.
Irritable bowel syndrome (IBS) is a functional disease that can affect the quality of those who suffer from this condition. Individuals with IBS can make lifestyle changes that may modify or control the number and severity of episodes. Certain foods, medications, and hormone levels may trigger IBS episodes. Learn how to prevent the number and severity of IBS episodes of diarrhea and constipation.
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