Dose-Response Study of Phenylephrine for Preventing Spinal-Induced Hypotension During Cesarean Delivery with Combined Spinal-Epidural Anesthesia Under the Effect of Prophylactic Intravenous Ondansetron.

Background: Ondansetron reduces the median effective dose (ED50) of prophylactic phenylephrine to prevent spinal-induced hypotension (SIH) during cesarean delivery. However, the exact dose response of phenylephrine in combination with prophylactic ondansetron for preventing SIH is unknown. Therefore, this study aimed to determine the dose-response of phenylephrine to prevent SIH in cesarean delivery when 4 mg of ondansetron was used as a preventive method. Methods: A total of 80 parturients were enrolled and divided randomly into four groups (n = 20 in each group) who received either 0.2, 0.3, 0.4, or 0.5 µg/kg/min of prophylactic phenylephrine. Ten minutes before the initiation of spinal induction, 4 mg prophylactic ondansetron was administered. The effective dose of prophylactic phenylephrine was defined as the dose required to prevent hypotension after the period of intrathecal injection and up to neonatal delivery. The ED50 and ED90 of prophylactic phenylephrine and 95% confidence intervals (95% CI) were calculated using probit analysis. Results: The ED50 and ED90 for prophylactic phenylephrine to prevent SIH were 0.25 (95% CI, 0.15 to 0.30), and 0.45 (95% CI, 0.39 to 0.59) µg/kg/min, respectively. No significant differences were observed in the side effects and neonatal outcomes between the four groups. Conclusion: The administration of 4 mg of prophylactic ondansetron was associated with an ED50 of 0.25 (95% CI, 0.15~0.30) and ED90 of 0.45 (95% CI, 0.39~0.59) µg/kg/min for phenylephrine to prevent SIH.

Treatment of nausea in hospitalized patients with acute illness.

Evidence suggests that available antiemetics are equal to intravenous fluid treatment against acute nausea of other causes than motion sickness, pregnancy, anaesthesia, chemo- or radiation therapy. Each antiemetic is associated with adverse effects, which include movement disorders, sedation, and QT prolongation. Intravenous fluid and treatment directed against underlying pathology is recommended as a first-line treatment against nausea in these patients. If an antiemetic is clinically warranted, ondansetron has the most favourable ratio between side effects and price, as argued in this review.

The prophylactic antiemetic therapies in management of differentiated thyroid cancer patients with radioactive iodine therapy: a single-center, non-randomized clinical trial.

Objective: The present study was to investigate three different single-drug regimens to show which was more effective to reduce radioactive iodine therapy (RAI) associated nausea and vomiting, and to compare the occurrence of long-term gastrointestinal diseases after RAI therapy. Method: We performed a single-center, non-randomized clinical trial among patients who underwent RAI therapy from March 2016 to July 2022. Enrolled patients were divided into four cohorts based on the date of the treatment. cohort 1, with no preventive antiemetics; cohort 2, received 20 mg of pantoprazole per day for 3 days; cohort 3, received a 10 mg metoclopramide tablet two times daily for 3 days; cohort 4, oral ondansetron, 8 mg, twice daily for 3 days. The primary endpoints were proportion of patients who experience vomiting episodes and nausea during the 7-day hospital period. Secondary end points included Functional Living Index Emesis (FLIE) quality-of life questionnaires and the occurrence of gastrointestinal diseases. Results: A total of 1755 patients were analyzed, comprised of 1299 (74.0%) women and 456 (26.0%) men, with a median age of 44 years (range 18-78 years). The characteristics of patient were similar within the four groups. 465 (26.4%) patients developed RAI-associated nausea, and 186 (14.4%) patients developed RAI-associated vomiting. The rate of nausea was significantly decreased in the patients who were taking ondansetron when compared with the other cohorts (P<0.05), while the rate of vomiting (≥6 episodes) was slightly lower. As secondary endpoint, FLIE measures ondansetron scored highly compared to other cohorts, from baseline (mean score of 110.53 ± 17.54) to day 7 (mean score of 105.56 ± 12.48). In addition, 48 (2.7%) patients were found to be with gastrointestinal diseases at the end of one year follow up. Multiple RAI therapy and higher dose of I-131 per body weight revealed a significantly independent risk factors of developing gastrointestinal disorders. Conclusions: In conclusion, the present study demonstrated that short-term ondansetron could be an effective prophylactic agent in controlling RAI-associated nausea and vomiting. Furthermore, the risk of developing gastrointestinal disorders was significantly higher for patients with multiple RAI therapy and higher dose of I-131 per body weight.

Comparative efficacy of prophylactic protocols in reducing perioperative nausea and vomiting during video-assisted thoracoscopic radical resection of lung cancer.

Lung cancer, a global mortality leader, often necessitates Video-Assisted Thoracoscopic (VATS) surgery. However, post-operative nausea and vomiting (PONV) is common, highlighting a need for effective management and prevention strategies in this context. A retrospective case-control study at Fujian Medical University Union Hospital evaluated patients undergoing VATS radical resection of lung cancer between May and September 2022. Patients were categorized based on PONV prevention methods, and data encompassing demographics, surgical history, and postoperative adverse events s were analyzed to assess the association between prophylactic protocols and PONV incidence. The Netupitant and Palonosetron Hydrochloride (NEPA) group showed a significant reduction in PONV occurrences post-surgery compared to Ondansetron (ONDA) and Control groups, emphasizing NEPA's efficacy in alleviating PONV symptoms (P < 0.05). Furthermore, following VATS radical resection of lung cancer, NEPA markedly reduced the intensity of PONV symptoms in patients. Both univariate and multivariate logistic analyses corroborated that NEPA independently reduces PONV risk, with its protective effect also apparent in susceptible populations like females and non-smokers. NEPA utilization markedly reduced both the incidence and severity of PONV in patients undergoing VATS radical resection of lung cancer, serving as an independent protective factor in mitigating PONV risk post-surgery.

Virtual clinical QT exposure-response studies - A translational computational approach.

BACKGROUND AND PURPOSE: A recent paradigm shift in proarrhythmic risk assessment suggests that the integration of clinical, non-clinical, and computational evidence can be used to reach a comprehensive understanding of the proarrhythmic potential of drug candidates. While current computational methodologies focus on predicting the incidence of proarrhythmic events after drug administration, the objective of this study is to predict concentration-response relationships of QTc as a clinical endpoint. EXPERIMENTAL APPROACH: Full heart computational models reproducing human cardiac populations were created to predict the concentration-response relationship of changes in the QT interval as recommended for clinical trials. The concentration-response relationship of the QT-interval prolongation obtained from the computational cardiac population was compared against the relationship from clinical trial data for a set of well-characterized compounds: moxifloxacin, dofetilide, verapamil, and ondansetron. KEY RESULTS: Computationally derived concentration-response relationships of QT interval changes for three of the four drugs had slopes within the confidence interval of clinical trials (dofetilide, moxifloxacin and verapamil) when compared to placebo-corrected concentration-ΔQT and concentration-ΔQT regressions. Moxifloxacin showed a higher intercept, outside the confidence interval of the clinical data, demonstrating that in this example, the standard linear regression does not appropriately capture the concentration-response results at very low concentrations. The concentrations corresponding to a mean QTc prolongation of 10 ms were consistently lower in the computational model than in clinical data. The critical concentration varied within an approximate ratio of 0.5 (moxifloxacin and ondansetron) and 1 times (dofetilide, verapamil) the critical concentration observed in human clinical trials. Notably, no other in silico methodology can approximate the human critical concentration values for a QT interval prolongation of 10 ms. CONCLUSION AND IMPLICATIONS: Computational concentration-response modelling of a virtual population of high-resolution, 3-dimensional cardiac models can provide comparable information to clinical data and could be used to complement pre-clinical and clinical safety packages. It provides access to an unlimited exposure range to support trial design and can improve the understanding of pre-clinical-clinical translation.

Prevention of postoperative nausea and vomiting after orthognathic surgery: a scoping review.

INTRODUCTION: Postoperative nausea and vomiting (PONV) is one of the most common adverse events following orthognathic surgery. It's a distressing feeling for patients and continues to be the cause of postoperative complications such as bleeding, delayed healing, and wound infection. This scoping review aims to identify effective PONV prophylaxis strategies during orthognathic surgery that have emerged in the past 15 years. METHODS: We searched Pubmed, Cochrane Controlled Register of Trials, and Embase from 2008 to May 2023. Studies meeting the following criteria were eligible for inclusion: (1) recruited patients undergo any orthognathic surgery; (2) evaluated any pharmacologic or non-pharmacologic method to prevent PONV. Studies meeting the following criteria were excluded: (1) case series, review papers, or retrospective studies; (2) did not report our prespecified outcomes. RESULTS: Twenty-one studies were included in this review. Pharmacological methods for PONV prevention include ondansetron and dexamethasone (3 studies), peripheral nerve block technique (4 studies), dexmedetomidine (1 study), pregabalin (2 studies), nefopam (2 studies), remifentanil (1 study), propofol (2 studies), and penehyclidine (1 study). Non-pharmacologic methods include capsicum plaster (1 study), throat packs (2 studies) and gastric aspiration (2 studies). CONCLUSIONS: Based on current evidence, we conclude that prophylactic antiemetics like dexamethasone, ondansetron, and penehyclidine are the first defense against PONV. Multimodal analgesia with nerve block techniques and non-opioid analgesics should be considered due to their notable opioid-sparing and PONV preventive effect. For the non-pharmacological methods, throat packs are not recommended for routine use because of their poor effect and serious complications. More prospective RCTs are required to confirm whether gastric aspiration can prevent PONV effectively for patients undergoing orthognathic surgery.

Antiemetic activity of abietic acid possibly through the 5HT3 and muscarinic receptors interaction pathways.

The present study was designed to evaluate the antiemetic activity of abietic acid (AA) using in vivo and in silico studies. To assess the effect, doses of 50 mg/kg b.w. copper sulfate (CuSO4⋅5H2O) were given orally to 2-day-old chicks. The test compound (AA) was given orally at two doses of 20 and 40 mg/kg b.w. On the other hand, aprepitant (16 mg/kg), domperidone (6 mg/kg), diphenhydramine (10 mg/kg), hyoscine (21 mg/kg), and ondansetron (5 mg/kg) were administered orally as positive controls (PCs). The vehicle was used as a control group. Combination therapies with the referral drugs were also given to three separate groups of animals to see the synergistic and antagonizing activity of the test compound. Molecular docking and visualization of ligand-receptor interaction were performed using different computational tools against various emesis-inducing receptors (D2, D3, 5HT3, H1, and M1-M5). Furthermore, the pharmacokinetics and toxicity properties of the selected ligands were predicted by using the SwissADME and Protox-II online servers. Findings indicated that AA dose-dependently enhances the latency of emetic retching and reduces the number of retching compared to the vehicle group. Among the different treatments, animals treated with AA (40 mg/kg) exhibited the highest latency (98 ± 2.44 s) and reduced the number of retching (11.66 ± 2.52 times) compared to the control groups. Additionally, the molecular docking study indicated that AA exhibits the highest binding affinity (- 10.2 kcal/mol) toward the M4 receptors and an elevated binding affinity toward the receptors 5HT3 (- 8.1 kcal/mol), M1 (- 7.7 kcal/mol), M2 (- 8.7 kcal/mol), and H1 (- 8.5 kcal/mol) than the referral ligands. Taken together, our study suggests that AA has potent antiemetic effects by interacting with the 5TH3 and muscarinic receptor interaction pathways. However, additional extensive pre-clinical and clinical studies are required to evaluate the efficacy and toxicity of AA.

Cholecystokinin-Induced Duodenogastric Bile Reflux Increases the Severity of Indomethacin-Induced Gastric Antral Ulcers in Re-fed Mice.

BACKGROUND/AIMS: We examined the involvement of cholecystokinin (CCK) in the exacerbation of indomethacin (IND)-induced gastric antral ulcers by gastroparesis caused by atropine or dopamine in mice. METHODS: Male mice were fed for 2 h (re-feeding) following a 22-h fast. Indomethacin (IND; 10 mg/kg, s.c.) was administered after re-feeding; gastric lesions were examined 24 h after IND treatment. In another experiment, mice were fed for 2 h after a 22-h fast, after which the stomachs were removed 1.5 h after the end of the feeding period. Antral lesions, the amount of gastric contents, and the gastric luminal bile acids concentration were measured with or without the administration of the pro- and antimotility drugs CCK-octapeptide (CCK-8), atropine, dopamine, SR57227 (5-HT3 receptor agonist), apomorphine, lorglumide (CCK1 receptor antagonist), ondansetron, and haloperidol alone and in combination. RESULTS: IND produced severe lesions only in the gastric antrum in re-fed mice. CCK-8, atropine, dopamine, SR57227 and apomorphine administered just after re-feeding increased bile reflux and worsened IND-induced antral lesions. These effects were significantly prevented by pretreatment with lorglumide. Although atropine and dopamine also increased the amount of gastric content, lorglumide had no effect on the delayed gastric emptying provoked by atropine and dopamine. Both ondansetron and haloperidol significantly inhibited the increase of bile reflux and the exacerbation of antral lesions induced by atropine and dopamine, respectively, but did not affect the effects of CCK-8. CONCLUSIONS: These results suggest that CCK-CCK1 receptor signal increases bile reflux during gastroparesis induced by atropine and dopamine, exacerbating IND-induced antral ulcers.

Ondansetron attenuates cisplatin-induced behavioral and cognitive impairment through downregulation of NOD-like receptor inflammasome pathway.

Cisplatin is an effective and commonly used chemotherapeutic drug; however, its use is accompanied by several adverse effects, including chemobrain. Ondansetron is a 5-HT3 antagonist, commonly used in prophylactic against chemotherapy-induced nausea and vomiting. Moreover, it has been identified as a novel neuroprotective agent in different animal models. However, its protective role against chemotherapy-induced chemobrain has not been investigated. The current study was the first study that explored the potential neuroprotective effect of ondansetron against cisplatin-induced chemobrain in rats. Cisplatin (5 mg/Kg) was injected intraperitoneally, once weekly, for 4 weeks with the daily administration of ondansetron (0.5 and 1 mg/Kg). Compared to the cisplatin-treated group, ondansetron administration showed a significant decrease in the latency time and a significant increase in ambulation, rearing, and grooming frequency in the open field test (OFT). Moreover, a significant improvement in the latency time in the rotarod and passive avoidance tests, following ondansetron administration. In addition, ondansetron treatment increased the percentage of alternation in the Y-maze test. Also, ondansetron showed a remarkable enhancement in the biochemical parameters in the hippocampus. It increased the acetylcholine (Ach) level and decreased the level of the acetylcholine esterase enzyme (AchE). Ondansetron significantly decreased interleukin-1ß (Il-1ß), tumor necrosis factor-alpha (TNF-α), toll-like receptor-4 (TLR-4), NOD-like receptor-3 (NLRP3) inflammasome as well as caspase-1 and caspase-3 levels. Furthermore, ondansetron significantly decreased the levels of copper transporter-1(CTR1) expression in the hippocampus. Collectively, these findings suggest that ondansetron may exhibit a neuroprotective and therapeutic activity against cisplatin-induced chemobrain.

The Effect of Granisetron, Ondansetron, and Meperidine in Preventing Postoperative Shivering: Controlled Clinical Trial.

BACKGROUND: Recently, use of HT35 receptor antagonists to prevent postoperative shivering has attracted a great deal of attention. This study was conducted with the aim of investigating the effectiveness of granisetron as an HT35 antagonist when compared with ondansetron and meperidine in preventing postoperative shivering. MATERIAL AND METHODS: In this triple blind random clinical trial study, 90 patients 18-50 years of age with ASA Class I and II undergoing general anesthesia were randomly assigned into one of the three drug groups: O (4-mg ondansetron), G (40 µg/kg of granisetron), and P (25 mg meperidine), immediately before induction of anesthesia. After anesthesia induction, at the end of the surgery, after the entrance and after leaving the recovery state, central temperature, peripheral temperature, heart rate, systolic blood pressure, diastolic blood pressure, and shivering were measured and documented. Two-tailed P < 0.05 was considered significant. RESULTS: In the meperidine, ondansetron, and granisetron groups, 4 (13.3%), 3 (10%), and 10 (33.3%) of patients experienced shivering during recovery, where the difference between the ondansetron and granisetron groups was significant (p-value=0.02). The variations in the mean arterial pressure during the investigation stages only in the ondansetron group were not significant (p>0.05). At the beginning of recovery, the reduction of peripheral temperature significantly was lower in the ondansetron group (p<0.05), while reduction of the central temperature was significantly (p<0.05) higher in the granisetron group. By the end of the recovery, the variations in the peripheral temperature across the three groups were consistent with the changes at the beginning of recovery, but variations of the central temperature across the three groups was not significantly diverse. CONCLUSION: Granisetron was not found to be much effective in preventing postoperative shivering. Ondansetron and meperidine were equally effective in preventing postoperative shivering. Ondansetron also causes less hemodynamic changes compared to other drugs, while granisetron is more effective in terms of preventing nausea and vomiting.

Comparison of Nausea and Vomiting Incidence After Laparoscopic Cholecystectomy With Pretreatment With Haloperidol and Ondansetron: A Randomization Clinical Trial Study.

OBJECTIVE: Nausea and vomiting after surgery are the most common complications. Therefore, we performed this study to compare the effect of ondansetron and haloperidol on nausea and vomiting after laparoscopic cholecystectomy. PATIENTS AND METHODS: In this randomized clinical trial, 60 patients candidates for elective laparoscopic cholecystectomy were allocated to haloperidol (0.05 mg/kg, n = 30) and ondansetron (0.15 mg/kg, n = 30) groups. An Ocular Analog Scale was used to assess postoperative nausea and vomiting. Every 15 minutes in the recovery room, heart rate and blood pressure were measured up to 6 hours after surgery. In addition, patient satisfaction was assessed postoperatively. RESULTS: Haloperidol and ondansetron have the same effect on postoperative nausea and vomiting in the recovery room and ward. It was found that the trend of Visual Analog Scale variable changes in the recovery room was similar in the haloperidol and ondansetron group ( P = 0.58); it was also true for the ward ( P = 0.79). Comparing the length of stay in a recovery room in the 2 groups was not statistically significant ( P = 0.19). In addition, the 2 groups did not differ in satisfaction postoperatively ( P = 0.82). CONCLUSION: Haloperidol and ondansetron had an equal effect on reducing nausea and vomiting in the recovery room and ward after laparoscopic cholecystectomy. Patient satisfaction and length of stay in the recovery room did not differ between groups.

Unveiling the antinociceptive mechanisms of Methyl-2-(4-chloro-phenyl)-5-benzoxazoleacetate: insights from nociceptive assays in mice.

OBJECTIVE: Methyl-2-(4-chloro- phenyl)-5-benzoxazoleacetate (MCBA), a synthetic benzoxazole derivative with established antipsoriatic efficacy, was investigated for potential antinociceptive effects. This study employs various nociceptive assays in mice to elucidate MCBA's antinociceptive mechanisms. MATERIALS AND METHODS: MCBA's antinociceptive potential was tested against various nociception models induced by formalin, glutamate, capsaicin, a transient receptor potential vanilloid 1 (TRPV1) receptor agonist, and phorbol 12-myristate 13-acetate, a protein kinase C (PKC) activator. It was then assessed using the hot plate test and examined within the acetic acid-induced writhing test. During the acetic acid-induced writhing test, MCBA was pre-challenged against selective receptor antagonists such as naloxone, caffeine, atropine, yohimbine, ondansetron, and haloperidol. It was also pre-challenged with ATP-sensitive potassium channel inhibitor (glibenclamide) to further elucidate its antinociceptive mechanism. RESULTS: The results showed that oral administration of MCBA led to a dose-dependent and significant inhibition (p < 0.05) of nociceptive effects across all evaluated models at doses of 60, 120, and 240 mg/kg. Moreover, the efficacy of MCBA's antinociceptive potential was significantly counteracted (p < 0.0001) by specific antagonists: (i) directed at adenosinergic, alpha-2 adrenergic, and cholinergic receptors using caffeine, yohimbine, and atropine, respectively; and (ii) targeting ATP-sensitive potassium channels, employing glibenclamide. Antagonists aimed at opioidergic and serotoninergic receptors (naloxone and ondansetron, respectively) had poor utility in inhibiting antinociceptive activity. Conversely, the dopaminergic receptor antagonist haloperidol potentiated locomotor abnormalities associated with MCBA treatment. CONCLUSIONS: MCBA-induced antinociception involves modulation of glutamatergic-, TRVP1 receptors- and PKC-signaling pathways. It impacts adenosinergic, alpha-2 adrenergic, and cholinergic receptors and opens ATP-sensitive potassium channels.

Comparison of prophylaxis strategy for postoperative nausea and vomiting and its incidence before and after the implementation of 5-hydroxytryptamine 3 in surgical setting: a single-center, retrospective study.

PURPOSE: To investigate the association between adherence to guideline-recommended risk-based postoperative nausea and vomiting (PONV) prophylaxis, the antiemetics used for PONV prophylaxis, and the incidence of PONV in patients who were underwent general anesthesia before and after 5-HT3 receptor antagonists became available. METHODS: Patients (≥ 20 years old) who were extubated after scheduled surgery and returned to general wards between January 2021 and February 2022 and between June 2022 and July 2023 were included. Risk factors included age < 50, female, motion sickness, nonsmoker, surgical factors, and postoperative opioid use. Two and three or more prophylaxis were recommended for patients with one or two and three or more risk factors, respectively. The primary outcome was the number of patients who received adequate prophylaxis, and the secondary outcomes were antiemetic agents used during anesthesia and the incidence of PONV on postoperative days 0 and 1. PONV was defined as documented PONV or rescue antiemetic administration. RESULTS: From January 2021 to February 2022 and from June 2022 to July 2023, 2342 and 2682 patients were included, respectively. Before ondansetron became available, more D2 receptor antagonists were used (p < 0.001), and after ondansetron became available, both ondansetron (p < 0.001) and propofol (p < 0.001) were given more frequently. Before and after ondansetron became available, the number of patients with adequate prophylaxis was 3.7% and 9.2%, respectively (p < 0.001), and the incidence of PONV on postoperative days 0 and 1 was 44.6% and 44.0%, respectively (p = 0.67). CONCLUSION: The availability of ondansetron increased the number of patients with adequate PONV prophylaxis, but did not decrease the incidence of PONV.

The Management of Nausea and Vomiting in Pregnancy and Hyperemesis Gravidarum (Green-top Guideline No. 69).

An objective and validated index of nausea and vomiting such as the Pregnancy-Unique Quantification of Emesis (PUQE) and HyperEmesis Level Prediction (HELP) tools can be used to classify the severity of NVP and HG. [Grade C] Ketonuria is not an indicator of dehydration and should not be used to assess severity. [Grade A] There are safety and efficacy data for first line antiemetics such as anti (H1) histamines, phenothiazines and doxylamine/pyridoxine (Xonvea®) and they should be prescribed initially when required for NVP and HG (Appendix III). [Grade A] There is evidence that ondansetron is safe and effective. Its use as a second line antiemetic should not be discouraged if first line antiemetics are ineffective. Women can be reassured regarding a very small increase in the absolute risk of orofacial clefting with ondansetron use in the first trimester, which should be balanced with the risks of poorly managed HG. [Grade B] Metoclopramide is safe and effective and can be used alone or in combination with other antiemetics. [Grade B] Because of the risk of extrapyramidal effects metoclopramide should be used as second-line therapy. Intravenous doses should be administered by slow bolus injection over at least 3 minutes to help minimise these. [Grade C] Women should be asked about previous adverse reactions to antiemetic therapies. If adverse reactions occur, there should be prompt cessation of the medications. [GPP] Normal saline (0.9% NaCl) with additional potassium chloride in each bag, with administration guided by daily monitoring of electrolytes, is the most appropriate intravenous hydration. [Grade C] Combinations of different drugs should be used in women who do not respond to a single antiemetic. Suggested antiemetics for UK use are given in Appendix III. [GPP] Thiamine supplementation (either oral 100 mg tds or intravenous as part of vitamin B complex (Pabrinex®)) should be given to all women admitted with vomiting, or severely reduced dietary intake, especially before administration of dextrose or parenteral nutrition. [Grade D] All therapeutic measures should have been tried before considering termination of pregnancy. [Grade C].

5-HT3a receptor contributes to neuropathic pain by regulating central sensitization in a rat with brachial plexus avulsion.

PURPOSE: As a frequently occurring complication resulting from brachial plexus avulsion (BPA), neuropathic pain significantly impacts the quality of life of patients and places a substantial burden on their families. Recent reports have suggested that the 5-HT3a receptor may play a role in the development and regulation of neuropathic pain. The current study aimed to explore the involvement of the 5-HT3a receptor in neuropathic pain resulting from BPA in rats. METHODS: A rat model of neuropathic pain was induced through brachial plexus avulsion (BPA). The pain thresholds of the rats were measured after BPA. The spinal dorsal horn (SDH) of rats was collected at day 14 after surgery, and the expression and distribution of the 5-HT3a receptor were analyzed using immunohistochemistry and western blotting. The expression levels of various factors related to central sensitization were measured by western blot, including c-Fos, GFAP, IBA-1, IL-1ß and TNF-α. The effects of 5-HT3a receptor antagonists on hyperalgesia were assessed through behavioral tests after intrathecal administration of ondansetron. Additionally, at 120 min postinjection, the SDH of rats was acquired, and the change of expression levels of protiens related to central sensitization were measured by western blot. RESULTS: BPA induced mechanical and cold hypersensitivity in rats. The 5-HT3a receptor was increased and mainly distributed on neurons and microglia in the SDH after BPA, and the level of central sensitization and expression of inflammatory factors, such as c-Fos, GFAP, IBA-1, IL-1ß and TNF-α, were also increased markedly. Ondansetron, which is a selective 5-HT3a receptor antagonist, reversed the behavioral changes caused by BPA. The antagonist also decreased the expression of central sensitization markers and inflammatory factors. CONCLUSION: The results suggested that the 5-HT3a receptor is involved in neuropathic pain by regulating central nervous system sensitization in a rat brachial plexus avulsion model. Targeting the 5-HT3a receptor may be a promising approach for treating neuropathic pain after brachial plexus avulsion.

Effect of preoperative ondansetron on postoperative nausea in healthy dogs undergoing laparoscopic gastropexy and castration.

OBJECTIVE: To investigate if preoperative ondansetron reduces postoperative nausea associated with laparoscopic gastropexy and castration in dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: Twenty client-owned, healthy male dogs. METHODS: Dogs were premedicated with dexmedetomidine (2-5 mcg kg-1) and methadone (0.2-0.5 mg kg-1) intramuscularly. General anesthesia was induced with propofol and maintained with an inhalant anesthetic agent. Dogs were randomized into group S (saline 0.1 mL kg-1, intravenously) or group O (ondansetron 0.2 mg kg-1, intravenously). Plasma and serum were collected before premedication and 3 hours postextubation to measure arginine vasopressin (AVP) and cortisol concentrations. Nausea scoring occurred before and 10 minutes after premedication, immediately after extubation, and at 1, 2 and 3 hours postextubation. Data were analyzed by mixed and split-plot anova with Bonferroni adjustment for the number of group comparisons. Significance was set at p < 0.05. RESULTS: Nausea scores increased over time at 1 (p = 0.01) and 2 (p < 0.001) hours postextubation in both groups compared with before premedication. Median nausea score (0-100 mm) for groups S and O before premedication were 2.5 and 0.5 mm, respectively. At 1 and 2 hours postextubation, group S scored 7.5 and 4.0 mm and group O scored 6.0 and 5.0 mm, respectively. No significant differences in nausea scores within or between groups were observed before premedication and 3 hours postextubation. Cortisol concentrations increased significantly 3 hours postextubation in both groups (p < 0.001) compared with before premedication, with no differences between groups. AVP concentrations showed no significant differences within or between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Preoperative intravenous administration of ondansetron (0.2 mg kg-1) did not impact postoperative nausea after laparoscopic gastropexy and castration. Investigation of higher doses of ondansetron on the incidence of postoperative nausea and vomiting in dogs after surgery is warranted.

Mechanisms underlying the laxative effect of lactulose: A randomized placebo-controlled trial showing increased small bowel water and motility unaltered by the 5-HT3 receptor antagonist, ondansetron.

BACKGROUND: Lactulose is a laxative which accelerates transit and softens stool. Our aim was to investigate its mechanism of action and use this model of diarrhea to investigate the anti-diarrheal actions of ondansetron. METHODS: A double-blind, randomized, placebo-controlled crossover study of the effect of ondansetron 8 mg in 16 healthy volunteers. Serial MRI scans were performed fasted and 6 h after a meal. Participants then received lactulose 13.6 g twice daily and study drug for a further 36 h. On Day 3, they had further serial MRI scans for 4 h. Measurements included small bowel water content (SBWC), colonic volume, colonic gas, small bowel motility, whole gut transit, and ascending colon relaxation time (T1AC), a measure of colonic water content. KEY RESULTS: Lactulose increased area under the curve (AUC) of SBWC from 0 to 240 min, mean difference 14.2 L · min (95% CI 4.1, 24.3), p = 0.009, and substantially increased small bowel motility after 4 h (mean (95% CI) 523 (457-646) a.u. to 852 (771-1178) a.u., p = 0.007). There were no changes in T1AC after 36 h treatment. Ondansetron did not significantly alter SBWC, small bowel motility, transit, colonic volumes, colonic gas nor T1AC, with or without lactulose. CONCLUSION & INFERENCES: Lactulose increases SBWC and stimulates small bowel motility; however, unexpectedly it did not significantly alter colonic water content, suggesting its laxative effect is not osmotic but due to stimulation of motility. Ondansetron's lack of effect on intestinal water suggests its anti-diarrheal effect is not due to inhibition of secretion but more likely altered colonic motility.

Review article: Efficacy of prophylactic ondansetron versus placebo or control in reducing vomiting in children undergoing ketamine procedural sedation in the emergency department: A systematic review and meta-analysis.

Ketamine is commonly used for procedural sedation anaesthesia in paediatric patients undergoing painful procedures in the ED. Ketamine's safety profile is excellent, but ketamine-associated vomiting (KAV) is common. Routine ondansetron prophylaxis could reduce KAV incidence. This literature review evaluated the efficacy of prophylactic ondansetron in reducing KAV incidence. A systematic literature review was performed on databases and trial registries on 14 January 2023 to identify randomised controlled trials. The primary outcome was reduction in KAV incidence, for any route of prophylactic ondansetron, in ED and up to 24 h post-discharge. ED length of stay, parental satisfaction and time to resumption of normal diet were secondary outcomes. Data analysis was performed using Revman 5.3. Meta-analysis was performed using random effects modelling. Risk of bias was assessed using the Cochrane Risk-of-Bias 2 tool. Evidence quality was assessed using Grading of Recommendation, Assessment Development and Evaluation methodology. Five trials with 920 participants met the eligibility criteria. Prophylactic ondansetron resulted in a reduction in KAV incidence overall odds ratio of 0.51 (95% confidence interval: 0.36-0.73). Intravenous and intramuscular prophylactic ondansetron showed benefit whereas the effect of oral administration was unclear. There was no difference between groups for secondary outcomes overall. The quality of evidence was deemed to be low overall because of high risk of bias and imprecision in outcome measures. This review found low to moderate certainty evidence that prophylactic ondansetron reduces KAV incidence. Methodologically rigorous research, with appropriately timed prophylactic ondansetron based on the route of administration, would further elucidate prophylactic oral ondansetron's efficacy.