MedicineNet.com
About Us | Privacy Policy | Site Map
January 7, 2009
  MedicineNet home Picture Slideshows Diseases and conditions Symptoms and signs Procedures and tests Medications Health and Living Health news and views MedTerms medical dictionary  
Font Size
A
A
A

Irritable Bowel Syndrome (cont.)

What is in the future for IBS?

The future of IBS depends on our increasing knowledge of the processes (mechanisms) that cause IBS. Acquiring this knowledge, in turn, depends on research funding. Because of the difficulties in conducting research in IBS, this knowledge will not come quickly. Until we have an understanding of the mechanisms of IBS, newer treatments will be based on our developing understanding of the normal control of gastrointestinal function, which is proceeding more rapidly. Specifically, there is intense interest in intestinal neurotransmitters, which are chemicals that the nerves of the intestine use to communicate with each other. The interactions of these neurotransmitters are responsible for adjusting (modulating) the functions of the intestines, such as contraction of muscles and secretion of fluid and mucus.

5-hydroxytriptamine (5-HT or serotonin) is a neurotransmitter that stimulates several different receptors on nerves in the intestine, including one called the 5-HT4 receptor. Stimulation of these receptors by 5-HT increases muscle contractions in the colon. An example of an experimental drug that affects intestinal neurotransmission is tegaserod. This drug mimics the effect of 5-HT on the 5-HT4 receptor. Thus, because it increases intestinal muscle contractions, tegaserod is being tested for effectiveness in treating constipation-predominant IBS as well as constipation in general.

Another drug that affects neurotransmission is ondansetron. This drug blocks a different receptor, the 5-HT3 receptor, and thereby reduces colonic contractions. Thus, ondansetron (Zofran) has been effective in treating diarrhea-predominant IBS in initial studies. There are drugs that stimulate another receptor, the 5-HT1 receptor. Examples of this type of drug are sumatriptan (Imitrex) and buspirone. These drugs are believed to reduce the responsiveness (sensitivity) of the sensory nerves to what's happening in the intestine. The 5-HT1 receptor stimulators, however, have not yet been tested for effectiveness in IBS. Finally, in preliminary studies, fedotozine has been shown to improve functional gastrointestinal symptoms. The mechanism of action of fedotozine is not known, but it also may act by reducing the sensitivity of the sensory nerves.

Finally, there is the issue of a relationship between IBS and intestinal bacteria. Over the next few years, much information will accumulate on this potential relationship.

IBS At A Glance
  • IBS is a functional disease, that is, a disease in which the intestine (bowel) functions abnormally.
  • Theories of the cause of IBS include abnormal input from intestinal sensory nerves, abnormal processing of input from the sensory nerves, and abnormal stimulation of the intestines by the motor nerves.
  • The primary symptoms of IBS are constipation, diarrhea, and abdominal pain. Secondary symptoms include abnormal passage of stool, abnormal form of stool, increased amounts of mucus in the stool, and a subjective feeling of abdominal distention (bloating).
  • IBS is diagnosed on the basis of typical symptoms (Rome II Criteria) and the absence of other intestinal and non-intestinal diseases that might give rise to the symptoms. Testing in IBS is directed primarily at excluding the presence of other intestinal diseases and non-intestinal diseases.
  • Treatment of IBS consists primarily of medications to control constipation, diarrhea, and abdominal pain. Anti-depressant medication and psychological treatments also may be used. It is not clear if dietary alterations have much effect on the symptoms of IBS except for increases in dietary fiber, which may improve constipation.
  • Although it has been hypothesized that IBS may be caused by intestinal bacteria, specifically by small intestinal bacterial overgrowth, there is little rigorous scientific support for the hypothesis.
  • Future advances in the treatment of IBS depend on a clearer understanding of its cause(s).

Last Editorial Review: 4/2/2007


Irritable Bowel Syndrome - How Was Diagnosis Established

The MedicineNet physician editors ask:

How was the diagnosis of your irritable bowel syndrome established?

Anonymously share your comment to help others. Patient Discussions FAQs
See 7 Viewer Comments

Submit Your Comment


Printer-Friendly Format  |  Email to a Friend


space Related health and medical articles From the Doctors at MedicineNet.com MedicineNet Doctors recommend space
space
MedicineNet Doctors Recommend Latest Medical News
space

GI Disorders

Get the latest treatment options.




Symptoms & Signs A-Z List Pinpoint Your Symptoms - Start Now Symptoms & Signs A-Z List Symptoms & Signs by Female Body Region Symptoms & Signs by Male Body Region

Topics Related to Irritable Bowel Syndrome


Irritable Bowel Syndrome
RSS FeedSpecialty RSS       Add to My Yahoo! What is this?

IBS Trigger FoodsIBS Trigger Foods
Everyone’s IBS is different, but something most sufferers have in common is symptom triggers. See more WebMD Videos »












Health categories:

Slideshows | Diseases & Conditions | Symptoms & Signs | Procedures & Tests | Medications | Health & Living | News & Views | Medical Dictionary

Popular health centers:

Allergies | Arthritis | Cancer | Diabetes | Digestion | Healthy Kids | Heart | Men's Health | Mental Health | Women's Health | More...

Publications:

ePublications (PDFs) | XML News via RSS | Audio Podcasts | Email Newsletters

MedicineNet.com:

About Us | Privacy Policy | Search Help | Site Map | WebMD® | Medscape® | eMedicine® | eMedicineHealth® | RxList®

HON Code We comply with the HONcode standard for health trust worthy information:
verify here.

©1996-2009 MedicineNet, Inc. All rights reserved. Notices and Legal Disclaimer.
MedicineNet does not provide medical advice, diagnosis or treatment. See additional information.