Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P46098 (5-HT3 receptor)
 2,290 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The use of ondansetron, a selective serotonin 5-HT3 receptor antagonist, is well established in patients with nausea and vomiting associated with cancer chemotherapy, radiotherapy or anaesthesia and surgery. The wide distribution of 5-HT3 receptors in the body and the role of these receptors in disease have provided the rationale for investigation of ondansetron in novel applications. Preliminary data have shown ondansetron to have clinical benefit in patients with nausea and vomiting associated with drug overdosage or poisoning, anti-infective or antidepressant therapies, uraemia or neurological trauma, and in patients with pruritus. Patients with gastrointestinal motility disorders (e.g. carcinoid syndrome, irritable bowel syndrome, diarrhoea associated with cryptosporidiosis or diabetes, and chronic refractory diarrhoea) have also shown some improvement when treated with ondansetron, as have patients with certain pain or CNS-related disorders [e.g. alcohol (ethanol) dependence, opiate withdrawal, vertigo, cerebellar tremor and Parkinson's disease treatment-related psychosis]. In contrast to conventional antiemetics, ondansetron is generally well tolerated with a lower incidence of sedation and only isolated case reports of extrapyramidal reactions. Furthermore, unlike dopamine receptor-blocking neuroleptics, ondansetron does not appear to worsen the symptoms of Parkinson's disease. Thus, in addition to its established indications, preliminary results suggest that ondansetron may be beneficial in a number of novel applications. This drug may represent a treatment alternative in patients with refractory disease, or an effective treatment of conditions for which current therapies are either poorly tolerated or not available. Further investigation of ondansetron in a range of potential new applications appears to be warranted.
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PMID:Ondansetron. A review of its pharmacology and preliminary clinical findings in novel applications. 911 22

Irritable bowel syndrome is characterized by recurrent abdominal pain and altered bowel function. In designing studies to evaluate new treatments for this disease, however, it is difficult to select appropriate endpoints to reflect improvement in the range of symptoms of the syndrome. In the present study we evaluated the parameter of adequate relief of abdominal pain and discomfort, as perceived by the patients, as a key endpoint for efficacy in the treatment of patients with irritable bowel syndrome. Abdominal pain and bowel function data were collected daily from 370 patients with the disease during treatment with placebo or a novel potent 5HT3 receptor antagonist. Once every 7 days adequate relief of pain and discomfort was assessed. Quality-of-life data were collected using self-administered questionnaires. The endpoint of adequate relief was significantly (P < 0.05) correlated with improvement in pain severity scores, percentage of pain-free days, percentage of days with urgency, improvement in stool frequency and consistency, and quality-of-life parameters. Adequate relief of pain and discomfort is significantly correlated with changes in multiple parameters associated with irritable bowel syndrome and can be used as an endpoint for assessing response to therapy in these patients.
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PMID:Adequate relief as an endpoint in clinical trials in irritable bowel syndrome. 960 85

A series of benzoxazoles with a nitrogen-containing heterocyclic substituent at the 2-position was prepared and evaluated for 5-HT3 partial agonist activity on isolated guinea pig ileum. The nature of the substituent at the 5-position of the benzoxazole ring affected the potency for the 5-HT3 receptor, and the 5-chloro derivatives showed increased potency and lowered intrinsic activity. 5-Chloro-7-methyl-2-(4-methyl-1-homopiperazinyl)benzoxazole (6v) exhibited a high binding affinity in the same range as that of the 5-HT3 antagonist granisetron, and its intrinsic activity was 12% of that of 5-HT. Compound 6v inhibited 5-HT-evoked diarrhea but did not prolong the transition time of glass beads in the normal distal colon even at a dose of 100 times the ED50 for diarrhea inhibition in mice. Compounds of this type are expected to be effective for the treatment of irritable bowel syndrome without the side effect of constipation.
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PMID:Benzoxazole derivatives as novel 5-HT3 receptor partial agonists in the gut. 968 41

Irritable bowel syndrome (IBS) represents one of the most common gastrointestinal-related diagnoses. Although the precise etiologic basis of IBS is not known, a common presenting symptom is abdominal pain or discomfort that is thought to develop, at least in part, from a heightened awareness of visceral nociceptive input. Agents capable of reducing this heightened visceral nociception would, therefore, have utility in the treatment of IBS. In this study we evaluated the effects of intravenous and intracerebroventricular administration of a 5-HT3 receptor antagonist, alosetron, on blood pressure changes associated with rectal distension in anesthetized and awake dogs. This vasoactive reflex serves as a model for visceral nociception. For intracerebroventricular studies, the cerebroventricular guides were placed over the lateral ventricle. In anesthetized studies, blood pressure was measured by femoral artery cannulation. In awake studies, blood pressure was monitored by noninvasive measurement. A rectal balloon was placed in the rectum of each dog and maintained throughout the experiments. Each dose of alosetron was given to the dogs as an intravenous or intracerebroventricular bolus, and every 30 min the rectal balloon was inflated and blood pressure responses observed. In both anesthetized and awake dogs alosetron produced a significant inhibition of the vasoactive reflex. In particular, alosetron showed high potency when administered intracerebroventricularly. Alosetron, administered either centrally or peripherally, appears to modulate the visceral nociceptive effect of rectal distension in dogs.
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PMID:Central modulation of rectal distension-induced blood pressure changes by alosetron, a 5-HT3 receptor antagonist. 995 18

Although it is unclear to what extent irritable bowel syndrome (IBS) symptoms represent a normal perception of abnormal function or an abnormal perception of normal function, many believe that IBS constitutes the clinical expression of an underlying motility disorder, affecting primarily the mid- and lower gut. Indeed, transit and contractile abnormalities have been demonstrated with sophisticated techniques in a subset of patients with IBS. As a consequence, drugs affecting gastrointestinal (GI) motility have been widely employed with the aim of correcting the major IBS manifestations, ie, pain and altered bowel function. Unfortunately, no single drug has proven to be effective in treating IBS symptom complex. In addition, the use of some medications has often been associated with unpleasant side effects. Therefore, the search for a truly effective and safe drug to control motility disturbances in IBS continues. Several classes of drugs look promising and are under evaluation. Among the motor-inhibiting drugs, gut selective muscarinic antagonists (such as zamifenacin and darifenacin), neurokinin2 antagonists (such as MEN-10627 and MEN-11420), beta3-adrenoreceptor agonists (eg, SR-58611A) and GI-selective calcium channel blockers (eg, pinaverium bromide and octylonium) are able to decrease painful contractile activity in the gut (antispasmodic effect), without significantly affecting other body functions. Novel mechanisms to stimulate GI motility and transit include blockade of cholecystokinin (CCK)A receptors and stimulation of motilin receptors. Loxiglumide (and its dextroisomer, dexloxiglumide) is the only CCKA receptor antagonist that is being evaluated clinically. This drug accelerates gastric emptying and colonic transit, thereby increasing the number of bowel movements in patients with chronic constipation. It is also able to reduce visceral perception. Erythromycin and related 14-member macrolide compounds inhibit the binding of motilin to its receptors on GI smooth muscle and, therefore, act as motilin agonists. This antibiotic accelerates gastric emptying and shortens orocecal transit time. In the large bowel a significant decrease in transit is observed only in the right colon, which suggests a shift in fecal distribution. Several 'motilinomimetics' have been synthesized. Their development depends on the lack of antimicrobial activity and the absence of fading of the prokinetic effect during prolonged administration. 5-hydroxytryptamine (5-HT)4 agonists with significant pharmacological effects on the mid- and distal gut (such as prucalopride and tegaserod) are available for human use. These 'enterokinetic' compounds are useful for treating constipation-predominant IBS patients. 5-HT3 receptor antagonists also possess a number of interesting pharmacological properties that may make them suitable for treatment of IBS. Besides decreasing colonic sensitivity to distension, these drugs prolong intestinal transit and may be particularly useful in diarrhea-predominant IBS. Finally, when administered in small pulsed doses, octreotide, besides reducing the perception of rectal distension, accelerates intestinal transit, although other evidence disputes such an effect.
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PMID:Management of irritable bowel syndrome: novel approaches to the pharmacology of gut motility. 1020 10

The purpose of this study was to investigate the pharmacological properties of the novel, selective 5-HT3 receptor antagonist, alosetron, and its effects on transit time in both the normal and perturbed small intestine of the rat. Alosetron concentration-dependently inhibited radioligand binding in membranes containing rat and human 5-HT3 receptors with estimated pKi values of 9.8 (n = 3) and 9.4 (n = 6), respectively. In selectivity studies alosetron had little or no significant affinity for any of the many other receptors and ion channels studied. Alosetron potently antagonized the depolarization produced by 5-HT in the rat vagus nerve (estimated pKB value of 9.8, n = 25). In anaesthetized rats, i. v. administration of alosetron inhibited 2-methyl-5-HT induced bradycardia (Bezold Jarisch index) at 1 and 3 microg kg-1, with an agonist dose ratio of approximately 3.0 at 1.0 microg kg-1, = 3-5). Alosetron administered via the duodenum also inhibited this reflex, with duration of action that was significantly longer than that seen with ondansetron (120-60 min, respectively, n = 6). Alosetron had no significant effect on normal small intestinal propulsion in the rat, but fully reversed the increase in intestinal propulsion (96%, n = 3) produced by egg albumin challenge. Alosetron is a highly selective 5-HT3 antagonist which normalizes perturbed small intestinal propulsion. Previous clinical data in IBS patients together with the transit data provide a good rationale for further studies with alosetron in IBS patients.
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PMID:The pharmacological properties of the novel selective 5-HT3 receptor antagonist, alosetron, and its effects on normal and perturbed small intestinal transit in the fasted rat. 1035 45

There is evidence from studies, in both animals and humans, that 5-HT3 receptor blockade has potential value in the treatment of irritable bowel syndrome, particularly in those patients with diarrhoea-predominant bowel habits. New findings suggest that 5-HT3 receptors exist on gut afferent neurones and that their activation by locally released 5-HT leads to visceral nociceptive stimulation, in addition to increased neuronally-mediated motor and secretory activity. If this concept is validated, it will provide a rationale for the use of 5-HT3 receptor antagonists in patients with increased gut motility, reduced fluid absorption and low nociceptive thresholds leading to abdominal pain. Alosetron is a highly selective, potent 5-HT3 receptor antagonist which is well absorbed with a long pharmacodynamic half-life. Its ability to provide long-lasting blockade of 5-HT3 receptors throughout the body make it an ideal candidate within its class to evaluate the clinical hypothesis that sustained and ubiquitous 5-HT3 receptor blockade is of value in the treatment of IBS.
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PMID:Review article: the therapeutic potential of 5-HT3 receptor antagonists in the treatment of irritable bowel syndrome. 1042 38

Distension of the gastrointestinal tract elicits abdominal pain, as well as sensations such as discomfort or fullness. Many patients with irritable bowel syndrome have been reported to show a reduced threshold to the pain or discomfort due to experimental rectal distension. This hypersensitivity of the gut may be characteristics of the irritable bowel, as well as other functional gastrointestinal disorders. Intestinal distension in animals induces a range of responses which have been used as indexes of visceral nociception. This paper reviews a recently introduced canine model used to assess the antinociceptive properties of a novel 5-HT3 receptor antagonist, alosetron.
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PMID:Review article: evaluation of drugs in experimental gut distension models. 1042 41

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal-related conditions. In this review, the safety and efficacy of alosetron, a potent and selective 5-HT3 receptor antagonist, in the treatment of IBS are discussed. Alosetron has been shown to produce statistically significant improvements in abdominal pain, stool consistency, stool frequency and urgency in female IBS patients. By contrast, no consistent improvement has been seen in male IBS patients treated with alosetron. The only adverse event of note with alosetron was constipation, and this represents a class effect of 5-HT3 receptor antagonists. In conclusion, alosetron is a safe and effective treatment for female IBS patients.
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PMID:Review article: the safety and efficacy of alosetron, a 5-HT3 receptor antagonist, in female irritable bowel syndrome patients. 1042 45

Subgroups of patients with irritable bowel syndrome (IBS) are likely to respond differently to existing and evolving therapies. The following criteria for subgrouping may be considered: (1) Patients with different predominant bowel habits respond differently to treatment (antidepressants, 5HT3-antagonists, psychotherapy). (2) Postprandial exacerbation of pain or other gastrointestinal symptoms is seen in approximately half of patients with IBS and may identify patients who are more responsive to some classes of drugs (e.g., those targeted at motility). (3) Women appear to respond differently from men to 5HT3-antagonists, and there may be gender differences in gastrointestinal physiology. (4) There is more overlap in the diagnosis of functional dyspepsia and IBS than would be predicted by chance, and both are associated with hyperalgesia to intraluminal distention.
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PMID:Patient subgroups in irritable bowel syndrome that can be defined by symptom evaluation and physical examination. 1058 71


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