Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022104 (irritable bowel syndrome)
 8,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Irritable bowel syndrome (IBS) carries a considerable economic and social impact which may, in part, be due to inefficient diagnosis and inappropriate treatment choice leading to continued patient ill health and absenteeism. Even assuming that IBS can be diagnosed positively, using well-established symptom-based criteria, management difficulties remain. Thus, pharmacological treatment choice is still based on the single predominant symptom, and many currently available treatments are ineffective in the long term. A greater understanding of the pathophysiology of IBS may lead to the development of more effective treatments that can target the multiple symptoms present in IBS. A new understanding of the role of serotonin (5-HT) and specific receptors (5-HT3 and 5-HT4) found in the gastrointestinal (GI) tract has led to the development of serotonergic agents which have potential clinical benefits. Recent clinical trials suggest that 5-HT4 receptor partial agonists, in particular, may have the ability to offer multiple symptom relief, without the risk of significant adverse reactions.
 ...
PMID:Treatment goals in irritable bowel syndrome. 1169 76

Serotonin (5-HT) is considered as a major mediator causing hyperalgesia and is involved in inflammatory reactions and irritable bowel syndrome. Alverine citrate may possess visceral antinociceptive properties in a rat model of rectal distension-induced abdominal contractions. This study was designed to evaluate the pharmacological properties of alverine citrate in a rat model of rectal hyperalgesia induced by 5-HTP (5-HT precursor) and by a selective 5-HT1A agonist (8-OH-DPAT) and to compare this activity with a reference 5-HT1A antagonist (WAY 100635). At 4 h after their administration, 5-HTP and 8-OH-DPAT increased the number of abdominal contractions in response to rectal distension at the lowest volume of distension (0.4 mL). When injected intraperitoneally before 8-OH-DPAT and 5-HTP, WAY 100635 (1 mg kg(-1)) blocked their nociceptive effect, but also reduced the response to the highest volume of distension (1.6 mL). Similarly, when injected intraperitoneally, alverine citrate (20 mg kg(-1)) suppressed the effect of 5-HTP, but not that of 8-OH-DPAT. However, when injected intracerebroventricularly (75 microg/rat) alverine citrate reduced 8-OH-DPAT-induced enhancement of rectal distension-induced abdominal contractions. In-vitro binding studies revealed that alverine citrate had a high affinity for 5-HT1A receptors and a weak affinity for 5-HT3 and 5-HT4 subtypes. These results suggest that 5-HTP-induced rectal hypersensitivity involves 5-TH1A receptors and that alverine citrate acts as a selective antagonist at the 5-HT1A receptor subtype to block both 5-HTP and 8-OH-DPAT-induced rectal hypersensitivity.
 ...
PMID:Rectal antinociceptive properties of alverine citrate are linked to antagonism at the 5-HT1A receptor subtype. 1169 52

Irritable bowel syndrome (IBS) is a functional GI disorder that is associated with abdominal discomfort and altered bowel habits. It accounts for up to 28% of patients presenting to a gastroenterology practice and poses a significant personal, societal and economic burden internationally. The Manning, Rome I and Rome II criteria were developed to identify appropriate IBS patients for entry into IBS studies in a consistent manner. Refinements in the understanding of the physiology of the enteric nervous system (ENS), which controls motility, secretion and sensation, provided the basis for our comprehension of the pathophysiology of IBS. Visceral hypersensitivity and neurotransmitter imbalance currently receive the most attention as possible mechanisms of IBS. This article outlines conventional treatments and reviews the data on emerging and experimental therapies for IBS. Emerging therapies for IBS using 5-HT mediation include 5-HT(3) antagonists, such as ondasetron, granisetron and alosetron, as well as 5-HT(4) agonists such as tegaserod and prucalopride. In addition to opioid agonists (e.g. fedotozine) several other drugs that act on other ENS receptors are being studied. In spite of significant progress in IBS research, these emerging therapies require more studies before they can be utilised as clinical treatments.
 ...
PMID:Emerging treatments for irritable bowel syndrome. 1177 29

Irritable bowel syndrome (IBS) is a common functional bowel disorder of unknown aetiology. It is defined by the presence of gastrointestinal (GI) symptoms including abdominal pain/discomfort, bloating and bowel motor dysfunction. No available therapy is yet effective against all the symptoms of the disorder. Current treatments therefore target individual symptoms but may be accompanied by unpleasant side-effects. Tegaserod is a novel selective serotonin receptor type-4 (5-HT4) partial agonist with structural similarity to 5-HT Tegaserod stimulates small bowel and colonic motility and helps to normalise GI function. Clinical trials using a patient's assessment of efficacy demonstrate that tegaserod significantly improves key symptoms of IBS: abdominal pain/discomfort, bloating and constipation. Tegaserod is well tolerated with an excellent safety profile and represents a significant treatment advance in this difficult-to-treat disorder.
 ...
PMID:Tegaserod: a novel, selective 5-HT4 receptor partial agonist for irritable bowel syndrome. 1183 35

Drug development for functional gastrointestinal disorders is complex. These conditions involve central and peripheral physiological changes, together with psychological factors. Methodological problems have included a poor appreciation of the physiological and psychological correlates of patients' symptoms, a lack of animal models of proven relevance, and safety issues. Government, patient pressure groups and the Internet can also influence a drug's success. Most recent interest has focused on the serotonin (5-HT) modifying drugs. Cisapride has been withdrawn in some countries because of concerns related to QT prolongation and cardiac arrhythmias. The 5-HT3 antagonists, developed to modify visceral sensation, have caused constipation; alosetron, also withdrawn, caused ischaemic colitis. The 5-HT4 agonists induce peristalsis; tegaserod and prucalopride, both delayed in their development due to issues of safety and efficacy, benefit patients with 'constipation-predominant' irritable bowel syndrome or idiopathic constipation. 5-HT1 agonists improve impaired gastric accommodation and symptoms in patients with functional dyspepsia. Antidepressants also affect serotonin metabolism. Previous examples of success in this area involved drugs targeted at peripheral receptors mediating motor function or secretion. Modification of sensory function is a much more challenging objective. The experience with serotonin modifying drugs has been mixed, and some important lessons are there to be learnt.
 ...
PMID:Review article: the complexity of drug development for irritable bowel syndrome. 1187 86

1. 5-Hydroxytryptamine (5-HT) is known to produce a number of different effects in the gastrointestinal tract of various species, and has been proposed to play a key role in a number of intestinal disorders in man, including irritable bowel syndrome (IBS), although the receptors involved have yet to be established. The aim of the present study was to investigate the distribution and function of 5-HT(2B) receptors in human colon, and to establish their possible role in the aetiology of IBS. 2. The distribution of 5-HT(2B) receptor mRNA and protein were investigated by quantitative RT - PCR, Western analysis and immunocytochemistry. High levels of both mRNA and protein for 5-HT(2B) receptors were found throughout the human gastrointestinal tract, and in particular in colon, where 5-HT(2B) receptors were found predominantly in the longitudinal and circular smooth muscle layers within the muscularis externa, and in the myenteric nerve plexus lying between these two layers. 3. Electrical field stimulation of longitudinal muscle preparations of human colon mounted in organ baths resulted in neuronally-mediated contractile responses, that were significantly potentiated by application of 5-HT (up to 10(-7) M), with a pEC(50) of 8.2 +/- 0.1 (n=49 donors). The response to 5-HT was inhibited by a number of selective 5-HT(2B) receptor antagonists. 4. This study has shown for the first time that, in contrast to animal studies, the excitatory effects of 5-HT in human colon are mediated by 5-HT(2B) receptors. It is proposed that these receptors contribute to the putative 5-HT-induced colonic smooth muscle hypersensitivity associated with IBS.
 ...
PMID:5-HT(2B) receptors play a key role in mediating the excitatory effects of 5-HT in human colon in vitro. 1187 20

Among serotonin receptors (5-HTRs), the 5-HT(4) subtype is of considerable interest because it is involved in (patho)physiological processes both in peripheral and central nervous systems. In addition to the clinical use of 5-HT(4R) agonists in the treatment of gastrointestinal motility disorders, the potential use of antagonists in the treatment of irritable bowel syndrome, arrhythmias and micturition disturbances are currently under investigation. This article will review the development of the most important classes of 5-HT(4R) antagonists with an emphasis on benzimidazole derivatives, their structure-affinity relationships, ligand-receptor interactions and pharmacological applications.
 ...
PMID:5-HT(4) receptor antagonists: structure-affinity relationships and ligand-receptor interactions. 1205 97

The role of 5-HT agents in the modulation of lower gastrointestinal function is discussed. Selective serotonin reuptake inhibitors are of potential benefit in functional gastrointestinal diseases although formal evidence is lacking. Novel pharmacological approaches include 5-HT(3) antagonists and 5-HT(4) agonists. These pharmacological classes have shown beneficial effects on a global efficacy end point, and ameliorated more than one symptom of lower gut function in clinical trials. They offer promise for the development of novel therapies for the treatment and control of irritable bowel syndrome.
 ...
PMID:Serotonergic modulation of visceral sensation: lower gut. 1207 74

Irritable bowel syndrome (IBS) comprises a major proportion of gastrointestinal and primary care practice worldwide. The past several years have seen the rapid evolution of a new and comprehensive model of IBS based on alterations in brain-gut interactions. Alterations in the bidirectional communication between the enteric nervous system and the central nervous system are implicated in the pathogenesis of IBS. 5-Hydroxytryptamine (5-HT; serotonin), a major neurotransmitter in the gastrointestinal tract, and its receptors 5-HT3 and 5-HT4 are involved in the control of gastrointestinal function. A number of abnormal motor and sensory patterns have been reported in patients with IBS. However, it is not known whether these abnormalities are related to symptoms or have a role in establishing a diagnosis of functional gastrointestinal disorders. Visceral hyperalgesia in IBS patients can be secondary to altered receptor sensitivity at the viscus itself and altered central modulation of sensation involving psychological influences in the interpretation of these sensations. The development of diagnostic criteria for IBS helps to avoid unnecessary and costly investigations. A detailed history allows us to diagnose IBS and search for another cause if warning symptoms are present. The Rome criteria are presently used to define IBS and are currently the most widely applied criteria used in clinical diagnosis and research purposes. Abdominal pain or discomfort associated with chronic altered bowel habits are the mainstay in diagnosis, while the supportive criteria may be used to further classify IBS patients into diarrhea-predominant or constipation-predominant subgroups. Minimal diagnostic tests have been advocated in the initial diagnostic approach to patients with suspected IBS, depending on the predominant symptom. The therapeutic goals in IBS must focus on the overall well-being of the patient, including abdominal symptoms and the accompanying nonbowel symptoms and affective disorders. It is important to establish an effective physician-patient relationship and to reassure the patient once the diagnosis of IBS is made. Dietary modification may be of value in some patients with IBS. Dietary fiber is frequently recommended for patients with constipation-predominant IBS. Two novel serotonin agonists are currently under development for constipated IBS patients, tegaserod and prucalopride. Antidiarrheal agents, including loperamide and diphenoxylate, may help patients with diarrhea-predominant IBS. 5-HT3 receptor antagonists may play a role in the management of such patients in the future. Psychological treatment and antidepressants should be considered when IBS symptoms are severe or refractory or associated with psychological distress and impaired quality of life.
 ...
PMID:Irritable bowel syndrome: update on pathogenesis and management. 1211 90

Pain is perceived, transmitted, processed and modulated within an extensive network of neurotransmitters and hormones. Despite increasing knowledge about the biologic principles, even on the molecular level, the more we learn about the precise mechanisms of their interactions the more questions arise. It is also pertinent to remember that clinical scientists studying pain modulating pharmacologic agents always have to consider possible placebo effects [57-61]. Most of our knowledge regarding the function of neurotransmitter systems in the CNS has been provided by animal studies. Thus we cannot be sure that they have exactly parallel counterparts in humans. For instance, animal studies suggest an inverse relationship between brain and spinal cord concentrations of substance P. If these observations are converted to an interpretation of human fibromyalgia, low brain-tissue levels of both serotonin and substance P should be expected, while spinal cord serotonin concentrations would be low and spinal cord substance P would be high [1]. There is good evidence that 5-HT, its receptors, and their interactions with other neurotransmitters are essential for nociception and antinociception. The activities of 5-HT receptors can be studied by agonist and in humans especially by antagonist use. But even with a direct spinal application of selective agonists and antagonists, observations may still be confounded by (1) dose, as there can be a dose-dependent activation of different receptor subtypes; (2) type of nociceptive tests (e.g., thermal versus pressure versus chemical models), which may have differences in the way they are regulated; and (3) influences due to effects on temperature, blood flow or motor function. With this potential for variability, it is perhaps not surprising that there is some variability in the results of studies reporting on the effects of various 5-HT agonists and antagonists on nociceptive transmission within the spinal cord [62]. For instance, different 5-HT3 receptor densities could exist in various neuronal systems, one density type being completely inhibited at low concentrations, and the others only at higher concentrations of 5-HT3 receptor antagonists, thus resulting in contrary effects. Finally, the "endogeneous 5-HT tone" may greatly influence agonist and antagonist action. Considering this complexity of serotonin-mediated reactions, it is not surprising that treatment of pain by 5-HT3 receptor antagonists appears to yield inconsistent results. As fibromyalgia is now regarded as a pain amplification syndrome with a broad variety of additional nonpain symptoms, the interrelations are complicated even more. Fibromyalgia associated symptoms (e.g., fatigue, insomnia, and irritable bowel syndrome) can be modulated by 5-HT3 receptor antagonists. From the data evaluated so far, there is evidence that 5-HT3 receptor antagonists provide significant benefit in some fibromyalgia patients. In our practice, the data justify a careful application in clinical use according to the study results. The dosage, route of application, long term adverse reactions and duration of therapy still need to be studied in greater detail. Recently reported adverse events from therapy of irritable bowel syndrome with alosetron [63-67] provide a note for caution before hastily using 5-HT3 receptor antagonists without more studies. One can surmise that, much as the biochemistry of depression has been elucidated by the development of the SSRIs, a greater understanding of the role of 5-HT3 receptor antagonists in treating fibromyalgia patients may provide some insights into disease mechanisms of this enigmatic disorder.
 ...
PMID:Current experience with 5-HT3 receptor antagonists in fibromyalgia. 1212 20


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>