Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0042963 (vomiting)
 31,883 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The availability of radiolabelled ligands selective for various putative neurotransmitter receptor sites and the development of quantitative autoradiography has led to a greater understanding of the neuronal pathway and receptor subtypes involved in the vomiting reflex induced by various mechanisms both within the central nervous system and the periphery. Receptors for acetylcholine, dopamine, histamine and serotonin have been detected in a number of brain regions associated with the vomiting reflex, and provide a rational basis for the antiemetic action of drugs that inhibit receptor subtypes for these neurotransmitters. The basis of the antiemetic action of other drugs such as dexamethasone and the cannabinoids is still obscure. Some drugs act on more than 1 receptor subtype. Metoclopramide may inhibit both dopamine D2- and 5-HT3 receptors in producing its antiemetic effect. Both metoclopramide and domperidone appear to have additional peripheral actions that contribute to their effectiveness. The cannabinoids are effective in cytotoxic-induced vomiting, perhaps acting via endorphin receptors or by inhibiting prostaglandin synthesis. The effectiveness of 5-HT3 receptor antagonists may depend on the block of both central and peripheral neuronal 5-HT3 receptors. Vomiting constitutes a major disadvantage to the use of many drugs; vomiting induced by aminoglycoside antibiotics appears to be due to ototoxicity and is relieved by histamine H1-receptor antagonists. The protracted vomiting associated with the use of some cytotoxics in cancer chemotherapy may involve psychic components, the chemoreceptor trigger zone and peripheral sensory neurons. Both 5-HT3 and dopamine D2-receptor antagonists exert some control, the former being more effective with cytotoxics of high emetogenic potential, such as cisplatin. Serotonin 5-HT3 receptor antagonists or high doses of metoclopramide in combination with anxiolytics and steroids as well as greater attention to pharmacokinetic profiles of the drugs involved would appear to offer improved control. The use of dopamine receptor antagonists in controlling emesis induced by dopamine agonists used in Parkinson's disease poses theoretical problems which can be overcome by using drugs with selectivity for the chemoreceptor trigger zone, such as domperidone or metoclopramide. However, higher doses of these drugs may produce some impairment of therapeutic responses to the agonists. Muscarinic and nicotinic agonists currently under investigation in Alzheimer's disease pose another therapeutic dilemma as emesis is due to a central action of these compounds. Several sites may be involved including the chemoreceptor trigger zone and frontal lobes. Opiates may act through dopamine receptors or mu-receptors on dopaminergic nerves, but serotonergic mechanisms may also be involved in the action of some opiates.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pharmacological agents affecting emesis. A review (Part I). 137 16

Ondansetron (GR 38032) has potent and highly selective antagonist properties at the 5-hydroxytryptamine (5-HT, serotonin) 5-HT3 receptor. The selectivity ratio for ondansetron on 5-HT3 receptors compared with actions on other neurotransmitter receptor types is greater than 1,000. The antiemetic properties of ondansetron have been determined in ferrets against the nausea and vomiting induced by cisplatin, cyclophosphamide, and whole-body radiation. Ondansetron (intravenous 0.01 to 0.1 mg/kg or subcutaneous 0.1 to 0.5 mg/kg) or metoclopramide (1.0 to 4.0 mg/kg) cause dose-dependent inhibitions of the vomiting induced by each of these procedures. Unlike ondansetron, the effects of metoclopramide are accompanied by moderate to marked behavioral depression. Since metoclopramide is 50 times more potent on dopamine D2 receptors than on 5-HT3 receptors, the behavioral depression is likely due to profound blockade of dopamine receptors. The 5-HT3 receptors have been shown to be present peripherally on vagal afferent fibers and are densely located in the vomiting center of the hindbrain. The current hypothesis is that there may be both a peripheral and a central site of action for ondansetron and other 5-HT3 antagonists. The lack of antagonist activity on dopamine and other non-5-HT3 receptors indicates that, unlike metoclopramide, ondansetron will not cause extrapyramidal or other dose-limiting side effects.
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PMID:Pharmacology and preclinical antiemetic properties of ondansetron. 138 45

The basic pharmacological mechanisms involved in mediating nausea and vomiting are still poorly understood. Several classes of drugs have been identified that alleviate the symptoms of nausea and vomiting, either prophylactically or acutely. None of these is completely effective in all cases. They include antihistamines, dopamine antagonists, steroids, cannabinoids, benzodiazepines, serotonin antagonists, and anticholinergics. This paper examines the evidence that links each of these classes of drugs with the distribution of specific neurotransmitter receptor sites on which they may be acting. Studies on the central nervous system distribution of binding sites for one of these classes of drugs, the anticholinergics, are described. Binding sites for the muscarinic cholinergic radioligand [3H]quinuclidinylbenzilate occur in different concentrations throughout the dorsal vagal complex of the rabbit medulla oblongata. The distribution of such sites in this nonvomiting experimental animal is markedly different from that in the cat, an animal that has been used for many physiological and pharmacological studies of emesis. A previous study has suggested that muscarinic binding sites may occur presynaptically on vagal afferent terminals that synapse in the dorsal vagal complex of the cat; this appears not to be the case in the rabbit. Possible implications of these findings for the identification of the site of action of anticholinergic, antiemetic drugs are discussed.
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PMID:The neuropharmacology of emesis: the role of receptors in neuromodulation of nausea and vomiting. 231 Oct 5

A growing interest has been shown in antiemetics with important advances in understanding the physiology of vomiting and the development of new anticancer agents having high emetic potential such as cisplatin. At present, high-dose metoclopramide, dexamethasone and butyrophenones have shown effective antiemetic action. In addition, antiemetic drug combinations that affect more than one neurotransmitter receptor have achieved improved emesis control. While improvements have been made in acute chemotherapy-induced emesis, anticipatory and delayed emesis is still a difficult problem. Further studies under well-designed trials are necessary to establish which of the available agents, doses, routes of administration, and schedules are best for reducing emesis depending on the chemotherapeutic drugs used.
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PMID:[The control of chemotherapy-induced nausea and vomiting]. 389 22

Ondansetron controls cisplatin-induced emesis when given in three 0.15 mg/kg doses, and preliminary data suggest that control may be maintained when fewer doses are employed. Prior trials have further shown improved antiemetic effects and fewer adverse effects of cisplatin treatment when neurotransmitter receptor blockers are combined with dexamethasone. This trial was undertaken to determine the effectiveness of the combination of dexamethasone and ondansetron and to see if equivalent results could be obtained with only two doses of ondansetron. There were 44 patients receiving initial cisplatin at a dose > or = 100 mg/m2, each given dexamethasone 20 mg and randomized to receive either two or three 0.15 mg/kg doses of ondansetron. Vomiting prevention was identical (35%) whether two or three doses were given. No new adverse effects were noted and cisplatin-induced diarrhea, usually seen in up to 60% of patients given this dose of cisplatin, was noted in only 5%. Although this trial did not demonstrate enhanced antiemetic effects with the combination, other investigators have done so and all agree that the regimen is safe and reduces adverse effects. Further exploration and use of the combination of ondansetron and dexamethasone, and studies testing fewer doses of ondansetron in this regimen are warranted.
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PMID:Randomized phase II trial comparing two versus three doses of ondansetron when used in combination with dexamethasone in patients receiving cisplatin > or = 100 mg/m2. 819 16

A wide variety of causes may be responsible for nausea and vomiting in terminal illness. The different emetic stimuli reach the vomiting centre by a variety of pathways and can be blocked by specific antiemetics that act at the neurotransmitter receptor sites in these pathways. A knowledge of the neurotransmitter receptor antagonist potency of the different antiemetics allows the choice of the most appropriate antiemetic for the relief of the nausea and vomiting caused by a particular emetic stimulus. To demonstrate the efficacy of this approach to the management of nausea and vomiting in terminal illness, the outcome of antiemetic choice in 100 consecutive episodes is recorded.
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PMID:Results of antiemetic management in terminal illness. 839 2

Vomiting can be a symptom of serious disease. Although it is important to correctly diagnose the cause of vomiting so the underlying disease can be treated, often antiemetic drugs must be used for the well being of the patient. First the physiology of vomiting with the neurotransmitter receptor system and the neuroanatomical neuron pathway is reviewed. Then a synopsis of antiemetic drugs currently used in veterinary medicine is presented with classification according to receptor antagonism. Finally novel drugs used to control vomiting in human patients and which may play a future role for the veterinary patient are discussed.
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PMID:[Vomiting: causes and therapy]. 900 42

Vomiting, the culminating sign of nausea, is primarily a protective reflex occurring in a wide variety of vertebrates. Even tough nausea and vomiting are among the most basic neural reflexes, they remain poorly understood. Poorly understood are the pathogenetic mechanisms from the anatomic receptor and neuroendocrine point of view. This is the reason why drugs are useful in some types of vomiting but not in others. The aim of this paper is to summarize current knowledge about anatomy of vomiting reflex, neurotransmitter receptor subtypes, agonists and antagonists of serotonin and substance P. Particularly in the treatment of post-chemotherapy and postoperative vomiting. It is pointed out that nausea an vomiting may be field of neurochemical and neuropharmacological research. Finally, in clinical research drugs for vomiting therapy may be useful in other pathologies (migraine, rheumatoid arthritis, bronchial asthma).
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PMID:[Vomiting]. 1220 99

This chapter briefly describes the physiological neural mechanisms by which diverse neurotransmitter receptor systems control several aspects of gastrointestinal functions such as motility, secretion, feeding, and emesis. The current techniques used to study the effects of cannabinoids on these gastrointestinal functions are then sequentially described, starting with isolated gastrointestinal muscle preparations and ultimately evolving to whole animal models. Both delta9-tetrahydrocannibinol (delta9-THC) and well-studied representatives of other classes of exogenous cannabinoid CB1/CB2 receptor agonists inhibit gastrointestinal motility, peristalsis, defecation, and secretions via cannabinoid CB1 receptors since the CB1 (SR141716A)- and not the CB2 (SR144528)-receptor antagonist reverses these effects in a dose-dependent manner. In addition, exogenous cannabinoids inhibit vomiting produced by diverse emetic stimuli in a SR141716A-sensitive manner in different animal models of emesis. Often these cannabinoids produce hyperphagic effects under laboratory conditions in most human and animal models of feeding. Administration of SR141716A by itself can produce effects opposite to cannabinoid agonists (e.g., increases in gastrointestinal motility and secretions, hyperphagia and vomiting), which suggests an important role for endocannabinoids in these gastrointestinal functions. Indeed, the presence of cannabinoid CB1 receptor markers, endocannabinoids such as anandamide and 2-arachidonoylglycerol (2-AG), their metabolic enzymes, and an endocannabinoid reuptake system have been confirmed in the gastrointestinal tract (GIT). The well-studied endocannabinoid anandamide also seems to reduce both gastrointestinal motility and secretion while producing hyperphagia. On the other hand, while the less well-investigated endocannabinoid 2-AG is a potent emetogen, anandamide may possess weak antiemetic activity.
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PMID:Methods evaluating cannabinoid and endocannabinoid effects on gastrointestinal functions. 1650 8