Characterization of Pain Processing Mechanisms in Irritable Bowel Syndrome

2014-07-24 14:30:20 | BioPortfolio


This study is being done to collect new information on irritable bowel syndrome, a disease that causes abdominal pain that does get better with treatment or keeps coming back ("chronic"). To better understand what causes the irritable bowel syndrome, we are studying drugs used to treat pain, dextromethorphan, naloxone, fentanyl, and lidocaine. We will study the effects these drugs have on experimental pain.

Dextromethorphan is used in non-prescription cough syrups. Naloxone is used for reversing the effects of narcotic pain relievers. Fentanyl is a narcotic used to treat pain and to make a person relaxed (sedated) before anesthesia. The purpose of this study is to see what kinds of pain are affected by these drugs in persons who have irritable bowel syndrome and persons who do not have this problem.


Irritable Bowel Syndrome (IBS) is a common gastrointestinal disorder characterized by chronic abdominal pain and altered bowel function (diarrhea and/or constipation) that effects up to 20% of the United States population. Although the pathophysiology of IBS is unknown, visceral hypersensitivity (i.e., decreased pain thresholds in response to gut distension) is a biological marker of the disorder. The mechanisms that lead to visceral hypersensitivity, however, are currently unknown. As a consequence of our current VA-supported studies, our laboratory has acquired evidence that patients with IBS and visceral hypersensitivity also have cutaneous hypersensitivity in response to experimental thermal pain stimuli. These new findings differ from previous investigations that indicated IBS-associated hypersensitivity is limited to the gut. Rather, our data suggest that patients with IBS have alterations in central pain processing mechanisms that may represent the underlying pathophysiological basis for visceral and cutaneous hypersensitivity. Based on our preliminary data, we propose that alterations in spinal processing mechanisms are similar in patients with IBS to those that have been described for patients with other chronic pain disorders. Cutaneous hypersensitivity is also seen in other chronic pain conditions such as fibromyalgia where altered central pain processing mechanisms have been shown to be responsible for maintaining hypersensitivity. In our current proposal, we hypothesize that IBS patients have increased peripheral and central afferent processing of nociceptive cutaneous and visceral stimuli.

Our objectives are as follows:

- Specific Objective #1. To determine if lidocaine applied to the rectum decreases visceral hyperalgesia, as tested by nociceptive rectal distension.

- Specific Objective #2. To determine if lidocaine applied to the rectum decreases cutaneous heat hyperalgesia to test for the presence or absence of central hyperalgesia in IBS patients.

- Specific Objective #3. To determine the relationships between doses of IV lidocaine, serum levels of IV lidocaine, and their anti-hyperalgesic effects, as tested by rectal distension and cutaneous heat stimulation.

Specific Objective #4. To determine the effect of rectal lidocaine on clinical pain and clinical symptoms of IBS.

The proposed studies will test the central hypothesis using well-controlled sensory stimuli designed to separately evaluate central and peripheral mechanisms. The objectives will be accomplished by systematically applying and comparing pharmacological and psychophysical studies to IBS patients and controls. This application is an extension of the principal investigator's current VA Advanced Career Development Award that examines the neurobiology of visceral hypersensitivity in Persian Gulf veterans who returned home with chronic abdominal pain. The proposed Clinical Research Program will study afferent mechanisms of visceral and cutaneous hypersensitivity in veterans with IBS. Our laboratory is uniquely positioned to use our expertise in psychophysical and pharmacologic evaluation of patients with fibromyalgia to study patients with IBS. The results of this current proposal will lead to larger clinical trials with sodium-channel blockers (i.e., lidocaine, mexiletine) as potential therapeutic agents for veterans with IBS.

Study Design

Allocation: Randomized, Control: Placebo Control, Endpoint Classification: Pharmacokinetics/Dynamics Study, Intervention Model: Crossover Assignment, Masking: Double-Blind, Primary Purpose: Treatment


Irritable Bowel Syndrome


dextromethorphan, naloxone, fentanyl, lidocaine


Malcom Randall VAMC
United States




Department of Veterans Affairs

Results (where available)

View Results


Published on BioPortfolio: 2014-07-24T14:30:20-0400

Clinical Trials [2443 Associated Clinical Trials listed on BioPortfolio]

Characterization of Pain Processing Mechanisms in Irritable Bowel Syndrome

The purpose of this study is to provide new information and to determine which kinds of brief, tolerable, experimental pain are affected by the drugs being studied in patients with irritab...

A Study of BMS-562086 in Patients With Irritable Bowel Syndrome

The primary purpose of this study is to evaluate the effects of BMS-562086 on small bowel and colonic transits in female subjects with diarrhea-predominant irritable bowel syndrome (D-IBS)

Acupuncture for Irritable Bowel Syndrome

Little is known about acupuncture's efficacy for Irritable Bowel Syndrome (IBS). This trial uses a manualized acupuncture treatment format that closely follows clinical practice and allow...

A Trial for New Treatment of Adult Patients With Irritable Bowel Syndrome

A study to evaluate the effectiveness of oral doses of Blautix in adult subjects with irritable bowel syndrome (IBS)

Fecal Microbiota Transplantation for Irritable Bowel Syndrome

Fecal microbiota transplantation (FMT) is a strategy that infuses a fecal suspension containing a healthy donor's microbiota into a patient's gut to restore his/her intestinal microbiome. ...

PubMed Articles [5746 Associated PubMed Articles listed on BioPortfolio]

Review article: an analysis of safety profiles of the treatments for diarrhoea-predominant irritable bowel syndrome.

Irritable bowel syndrome (IBS) is multifactorial in nature, and a wide range of therapies are available to manage symptoms of this common disorder.

Pycnogenol® supplementation improves the control of irritable bowel syndrome symptoms.

The aim of this registry was to evaluate the effects of Pycnogenol® on the main symptoms of irritable bowel syndrome (IBS) in otherwise healthy individuals.

Association between Allergic Diseases and Irritable Bowel Syndrome: A Retrospective Study.

The relationship between allergic disease and irritable bowel syndrome (IBS) is poorly understood. We aimed to investigate the potential association as well as the underlying immunological mechanisms.

Is endometriosis associated with irritable bowel syndrome? A cross-sectional study.

Previous studies have found a high prevalence of irritable bowel syndrome (IBS). However, data on this relation in women without bowel endometriosis is limited. The aim of this study was to compare th...

Irritable bowel syndrome subtypes and characteristics in children from Panama, Ecuador,El Salvador, Nicaragua and Mexico.

Few pediatric studies classify the irritable bowel syndrome (IBS) subtypes.

Medical and Biotech [MESH] Definitions

Chronic or recurrent colonic disorders without an identifiable structural or biochemical explanation. The widely recognized IRRITABLE BOWEL SYNDROME falls into this category.

A disorder with chronic or recurrent colonic symptoms without a clearcut etiology. This condition is characterized by chronic or recurrent ABDOMINAL PAIN, bloating, MUCUS in FECES, and an erratic disturbance of DEFECATION.

A subspecies of Bifidobacterium longum that occurs in the GASTROINTESTINAL TRACT of human infants and is used as a PROBIOTIC. It may also be used in the treatment of IRRITABLE BOWEL SYNDROME.

A potent narcotic analgesic, abuse of which leads to habituation or addiction. It is primarily a mu-opioid agonist. Fentanyl is also used as an adjunct to general anesthetics, and as an anesthetic for induction and maintenance. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1078)

A malabsorption syndrome resulting from extensive operative resection of the SMALL INTESTINE, the absorptive region of the GASTROINTESTINAL TRACT.

More From BioPortfolio on "Characterization of Pain Processing Mechanisms in Irritable Bowel Syndrome"

Quick Search


Relevant Topics

Irritable Bowel Syndrome IBS
Irritable bowel syndrome (IBS) is a common but poorly understood chronic (long-term) condition where the normal functions of the bowel are disrupted. Symptoms of IBS include abdominal pain or discomfort, changes in bowel habits and bloated feelings. ...

Pain is defined by the International Association for the Study of Pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage”. Some illnesses can be excruci...

An anesthesiologist (US English) or anaesthetist (British English) is a physician trained in anesthesia and perioperative medicine. Anesthesiologists are physicians who provide medical care to patients in a wide variety of (usually acute) situations. ...

Searches Linking to this Trial