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

Ondansetron, a specific 5-hydroxytryptamine3 (5-HT3)-blocker, injected s.c. (0.038, 0.075, 0.15 or 0.3 mg/kg) every 12 h with the fourth dose given 0.5 h before restraint at 4 degrees C (stress) or oral administration (p.o.) of 1 ml 80% ethanol, dose-dependently prevented gastric mucosal damage in female Sprague-Dawley rats (160-180 g); the animals were killed 2 or 1 h after stress or ethanol p.o., respectively. A similar pretreatment regimen with cyproheptadine (0.1, 0.25 or 0.5 mg/kg) or ketanserin (15, 30, or 75 micrograms/kg), both being 5HT2-receptor antagonists, also dose-dependently lowered the severity of stress- or ethanol-induced mucosal lesions. Only the higher doses of phenobarbitone (25 or 50 mg/kg given s.c. in a single dose 0.5 h beforehand) inhibited stress-induced gastric ulcers; however, even the lowest non-antinuclear dose (12.5 mg/kg), effectively produced CNS depression. These preliminary findings suggest that 5HT3-receptor blockade not only can antagonise stress- or ethanol-evoked gastric mucosal damage, but also may act through a peripheral mechanism.
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PMID:5-Hydroxytryptamine3-receptor blockade protects against gastric mucosal damage in rats. 134 85

The 5-HT3 receptor antagonists such as ondansetron have been shown to have anxiolytic-like activity in a wide range of preclinical tests: in the mouse black: white test, the rat social interaction test, the rat elevated X-maze and the marmoset human threat test. Ondansetron, like other 5-HT3 receptor antagonists appears to have important advantages over existing anxiolytic therapies. Thus, the 5-HT3 receptor antagonists are not sedative, they do not have addictive liabilities, there are no problems of withdrawing from chronic treatment and they can be used following benzodiazepine withdrawal. Such compounds even inhibit the behavioural syndrome associated with withdrawal from drugs of abuse, nicotine, alcohol, cocaine, opiates. The preclinical data, therefore, indicates the 5-HT3 receptor antagonists as novel anxiolytics of the future, and there is new clinical work in support of this suggestion.
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PMID:Anxiolytic potential of 5-HT3 receptor antagonists. 134 46

The efficacy of ondansetron, a selective 5-HT3 receptor antagonist, in preventing postoperative nausea and vomiting in surgical patients was studied. Fifty women were randomized in a double-blind manner to receive either two 8 mg doses of intravenous ondansetron or two doses of placebo vehicle: the first given just before general anesthesia induction and the second 8 hours later. During the first 24 postoperative hours, the number of emetic episodes was recorded and the subjects rated their nausea on a scale from 0 to 10. Ondansetron-treated subjects had fewer emetic episodes (p less than 0.001) and lower subjective nausea scores (p less than 0.001). The number of complete responders (no emetic episodes and no rescue therapy) was 1 of 24 (4%) and 15 of 26 (58%) in the placebo and ondansetron groups, respectively (p less than 0.001). Ondansetron is clearly more effective than placebo in the prophylaxis of postoperative nausea and vomiting. The adverse event profile for ondansetron was similar to that of placebo.
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PMID:Ondansetron is effective in decreasing postoperative nausea and vomiting. 138 67

Ondansetron (GR38032F), a serotonin 5HT3 antagonist, is active in numerous behavioral paradigms and neurochemical systems. Since 5HT3 antagonists have been suggested as therapeutic agents for the treatment of drug abuse, the action of ondansetron on cocaine drug discrimination and self-administration paradigms in rats was investigated. Doses of ondansetron (0.001 - 1.0 mg/kg) had no effect on the discriminative stimulus properties of 10 mg/kg cocaine. In contrast SCH23390, a dopamine D1 antagonist known to block cocaine discrimination, acted as previously reported. Ondansetron did not augment the effects of SCH23390, but at higher doses, combinations of ondansetron and SCH23390 produced disruption of lever pressing in the presence of cocaine. Ondansetron (0.001-1.0 mg/kg) had no effect on the self-administration of various doses of cocaine, nor did it have any effect on reacquisition of cocaine self-administration in animals with a history of active administration followed by a period of abstinence. As before, SCH23390, known to block cocaine self-administration, acted as previously reported. Although other 5HT antagonists may prove to be efficacious in cocaine abuse, ondansetron appears unlikely to alter the subjective or rewarding stimulus properties of cocaine.
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PMID:Failure of ondansetron to block the discriminative or reinforcing stimulus effects of cocaine in the rat. 138 19

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 anti-emetic effects, safety and usefulness of ondansetron, a 5-HT3 receptor antagonist, given orally once daily for 3-5 consecutive days, were investigated in patients receiving a high single dose (greater than or equal to 50 mg/m2 or 75 mg/body) or lower multiple doses (greater than or equal to 15-20 mg/m2/day for 3-5 consecutive days) of cisplatin. Ondansetron 4 mg was administered orally once daily for 3-5 consecutive days. Efficacy rates in controlling nausea and emesis over the 3-5 days were 77.3% (17/22 cases) and 66.7% (6/9 cases) in patients receiving a high single dose and lower multiple doses of cisplatin, respectively. Side effects were observed in 2 cases (headache and elevation of blood pressure in one case and only headache in the other case.). Abnormality in clinical laboratory findings was observed in 1 case. From the above, ondansetron, showing high efficacy by oral administration 4 mg once daily for 3-5 consecutive days, without any problem in safety, was considered to be a useful anti-emetic agent.
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PMID:[Investigation of anti-emetic effect of ondansetron tablet in multiple doses on nausea and emesis associated with cisplatin]. 138 74

Ondansetron, a potent and highly selective 5-HT3 receptor antagonist, prevents emesis following chemotherapy by antagonising the action of 5-hydroxytryptamine (5-HT) at 5-HT3 receptors on vagal afferent neurons that innervate the gastrointestinal tract and 5-HT3 receptors in the central vomiting system. Evidence suggests that chemotherapy induces the release of 5-HT from enterochromaffin cells in the small intestine. This stimulates vagal afferent nerves via 5-HT3 receptors. Information is then relayed, via the vagus nerve, to the central vomiting system. 5-HT3 receptors are also found in the hind-brain vomiting system including the area postrema (the site of the chemoreceptor trigger zone for emesis). Therefore, following chemotherapy, 5-HT activates 5-HT3 receptors at 2 sites to induce emesis. Clinical data showing that a single dose of ondansetron prevents acute emesis suggest that it is important to block the initiation of the emetic reflex. This may prevent the recruitment of central mechanisms involving 5-HT3 receptors.
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PMID:Mechanism of the anti-emetic activity of 5-HT3 receptor antagonists. 138 26

Ondansetron, a selective 5-HT3 receptor antagonist, has already been reported to have a marked effect to alleviate or prevent nausea and vomiting associated with cancer chemotherapy, after its intravenous administration. The present study was planned to examine the usefulness of its tablet form, which was prepared for the convenient use in outpatients receiving chemotherapy. In order to make an objective evaluation of anti-emetic effect and safety of ondansetron 4 mg tablet, this study was conducted in double-blind comparison versus placebo in patients receiving cisplatin at a single dose of 50mg/m2 or higher. Either 4 mg of ondansetron or placebo (lactose tablet) was administered orally once at 2 hrs prior to administration of cisplatin. If any satisfactory anti-emetic effects were not obtained, 4 mg of ondansetron injection was given once intravenously as a rescue medication. The inhibitory effect on nausea and vomiting was assessed in 4 grades as "excellent", "good", "fair" and "poor" based on severity of nausea and number of vomiting that occurred during the first 24hrs after administration of cisplatin. When rescue medication was conducted, the case was assessed as "poor". Ondansetron was significantly superior to placebo in inhibition of nausea and vomiting, in which efficacy rates (excellent+good) of ondansetron and placebo groups were 58.1% (25/43 cases) and 16.7% (7/42 cases), respectively. Number of cases requiring rescue medication with ondansetron injection was obviously greater in placebo group (31 cases) than that in ondansetron group (12 cases). In those patients given ondansetron injection as the rescue medication, satisfactory effects were obtained in 5 cases in ondansetron group and in 18 cases in placebo group. Although side effects including chest itching (ondansetron group), headache and dull headache (placebo group) were observed after the rescue medication with ondansetron injection, these symptoms were not severe and disappeared after 1-2 days. As mentioned above, ondansetron tablet was shown to possess excellent anti-emetic effect on nausea and emesis induced by high dose of cisplatin and to have no problem in safety. Hence ondansetron was proven to be clinically very useful anti-emetic.
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PMID:[Anti-emetic effect and safety of ondansetron tablet in double-blind comparison with placebo]. 141 14

Ondansetron is a 5-HT3 receptor antagonist which is effective and well tolerated as an antiemetic for emesis induced by cancer chemotherapy and radiation therapy, and in the prevention and treatment of postoperative nausea and vomiting. Ondansetron is rapidly absorbed after oral administration (tmax 1.9 h) with an absolute bioavailability of around 60%. Its terminal elimination half-life is 3.5 h and it is extensively hepatically metabolized. Plasma clearance is 0.38 litre h-1 kg-1 and volume of distribution is 1.8 litre kg-1. Plasma clearance is reduced by age (31% reduction) and hepatic failure (80% reduction in severe failure). In patients undergoing general anaesthesia there is a slight prolongation of terminal half-life, which is not of clinical significance. Ondansetron is very well tolerated in volunteer studies. Headache, mild abdominal pain, and constipation occur infrequently. There is no evidence for effects of ondansetron on cardiac function (electrocardiogram, cardiac output, blood pressure and heart rate), and haemostatic function in volunteers and patients. Respiratory depression induced during general anaesthesia is not potentiated by ondansetron. No drug interactions have been noted with temazepam, atracurium, alfentanil and alcohol in man. There are also no interactions seen in animal studies using pentobarbitone, morphine, neostigmine, prednisolone and diazepam.
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PMID:Clinical pharmacology of ondansetron in postoperative nausea and vomiting. 142 20

Ondansetron is a highly potent and selective antagonist at 5-HT3 receptors. Its anti-emetic actions were first revealed by its ability to antagonize retching and vomiting induced by chemotherapy and radiotherapy in animals and man. Subsequently, the availability of labelled 5-HT3 receptor ligands allowed identification of 5-HT3 receptors, located at highest densities in the area postrema, nucleus tractus solitarius (NTS), in other areas of the brain, and on afferent terminals of the vagus nerve. Postoperative nausea and vomiting may be caused by various factors: the anaesthetic, associated drugs, the surgical procedure, movement of the patient, sex, weight and pain. These factors mediate their effects via the higher brain circuits, the vestibular nuclei, the chemoreceptor trigger zone in the area postrema, or the upper gastrointestinal tract via the vagus nerve, influencing motor and visceral emetic outputs in the hind-brain. It is hypothesized that ondansetron blocks nausea and vomiting by 5-HT3 receptor antagonism at two specific sites: (i) centrally, in the area postrema/NTS; and (ii) peripherally on vagus nerve terminals. The absence of other pharmacological effects of ondansetron ensures an absence of side-effects.
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PMID:Pharmacology of ondansetron. 142 23


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