Hope for the Future

The Future Directions of IBS Treatments. Recent research has shown that in response to eating and the distention of the gut by food contents, a very important chemical serotonin (5-hydroxy-tryptamine; 5-HT) is released from specialised storage cells lining the gut (enterochromaffin cells).

5-HT (serotonin) is a very important chemical in the body, and is involved in transmission of information through the nervous system. That it plays a pivotal role in regulating the function of the gut is evident because the majority of the body's 5-HT or serotonin is stored in the gut.

The contraction of the smooth muscle of the intestines results in the movement of food through the gut (peristalsis). This movement of food along the intestine has been shown, in part, to be orchestrated by 5-HT. When released from the specialised storage cells (enterochromaffin cells), 5-HT attaches or binds to specialised sites or receptors that are located on the end of the nerves contained within the wall of the intestines. These nerves are responsible for controlling the contraction of the intestinal smooth muscle - peristalsis. When 5-HT binds onto a specific type of these receptors (the 5-HT4 receptor), peristalsis is initiated.

It follows therefore that if peristalsis is inadequate in the colon (this can cause constipation), a drug that would bind onto the 5-HT4 receptor and initiate peristalsis should be effective in alleviating constipation.

Based on very innovative basic physiological research, one such drug that binds on the 5-HT4 receptor and drives peristalsis has been developed by a pharmaceutical company called Novartis. The chemical name for this product is tegaserod. Tegaserod is a 5-HT4 receptor agonist, i.e. It copies the effects of 5-HT.

In clinical trials tegaserod has already been shown to be effective in the treatment of female patients with constipation predominant IBS, offering patients relief from the pain, bloating and constipation associated with their IBS. This drug may represent a major breakthrough in therapy for these patients.

It is the hope of this clinic that tegaserod will also be effective in treating patients with Primary Motility Disorder of the Midgut - another variant of IBS. Hopefully our research group will be able to carry out these studies to confirm this in the future.

In the same vein there is a clear need - in patients with diarrhoea predominant IBS (Functional Diarrhoea and Diarrhoea Predominant Spastic Colon Syndrome) in which some components of intestinal motility or contractility may be increased - to develop a blocker of the 5HT receptor (a 5HT antagonist). Work is currently proceeding to develop such a drug which may be able to offer these patients hope.

The properties of these 5-HT receptor active drugs are not just restricted to motility. Research shows that they also have the ability to reduce pain in IBS - pain is caused by the over activity of the nerve fibres within the wall of the intestine. Research also shows that 5-HT active drugs also play a part in controlling secretion into the gut, thus controlling the consistency of the stool that is formed.

These are the most hopeful and exciting developments we have yet seen in the treatment of IBS symptoms. This research should bring help and relief to a vast number of sufferers. We hope to be reporting on the progress of these developments on a regular basis.

   


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