Recent advances in antiemetics: new formulations of 5HT3-receptor antagonists

Effect of Prophylactic Tropisetron on Post-Operative Nausea and Vomiting in Patients Undergoing General Anesthesia: Systematic Review and Meta-Analysis with Trial Sequential Analysis

This systematic review and meta-analysis of randomized controlled trials (RCTs) with trial sequential analysis (TSA) aimed to comprehensively evaluate and compare the efficacy of the prophylactic administration of tropisetron in the prevention of the incidence of post-operative nausea and vomiting (PONV) in patients undergoing surgery under general anesthesia. This study was registered with PROSPERO (CRD42024372692). RCTs comparing the efficacy of the perioperative administration of tropisetron with that of a placebo, other anti-emetic agents, or a combination of anti-emetic injections were retrieved from the databases of Ovid-MEDLINE, Ovid-EMBASE, the Cochrane Central Register of Controlled Trials, and Google Scholar. The frequency of rescue anti-emetic use (RA) and the incidence of PON, POV, and PONV (relative risk [RR]: 0.718; 95% confidence interval [CI] 0.652-0.790; I2 = 0.0, RR: 0.587; 95% CI 0.455-0.757; I2 = 63.32, RR: 0.655; 95% CI 0.532-0.806; I2 = 49.09, and RR: 0.622; 95% CI 0.552-0.700; I2 = 0.00, respectively) in the tropisetron group were lower than those in the control group; however, the incidence of complete response (CR) was higher in the tropisetron group (RR: 1.517;95% CI 1.222-1.885; I2 = 44.14). TSA showed the cumulative Z-curve exceeded both the conventional test and trial sequential monitoring boundaries for RA, PON, POV, and PONV between the tropisetron group and the control group. Thus, the prophylactic administration of tropisetron exhibited superior efficacy in the prevention of PON, POV, and PONV. Furthermore, a lower incidence of RA and a higher incidence of CR were observed with its use.

Easing the Journey-an Updated Review of Palliative Care for the Patient with High-Grade Glioma

PURPOSE OF REVIEW

High-grade gliomas (HGG) are rare brain tumors that cause disproportionate suffering and mortality. Palliative care, whose aim is to relieve the symptoms and stressors of serious illness, may benefit patients with HGG and their families. In this review, we summarize the extant literature and provide recommendations for addressing the symptom management and communication needs of brain tumor patients and their caregivers at key points in the illness trajectory: initial diagnosis; during upfront treatment; disease recurrence; end-of-life period; and after death during bereavement.

RECENT FINDINGS

Patients with HGG experience highly intrusive symptoms, cognitive and functional decline, and emotional and existential distress throughout the disease course. The caregiver burden is also substantial during the patient's illness and after death. There is limited evidence to guide the palliative management of these issues. Palliative care is likely to benefit patients with HGG, yet further research is needed to optimize the delivery of palliative care in neuro-oncology.

Efficacy and Safety of Thalidomide As a Pre-Medication of Chemotherapy-Induced Nausea and Vomiting (CINV) Following Highly Emetogenic Chemotherapy (HEC): A Systematic Review and Meta-Analysis

Background

In China, thalidomide (THD) has been used to prevent chemotherapy-induced nausea and vomiting (CINV) following highly emetogenic chemotherapy (HEC); however, there is limited evidence on the efficacy and safety of THD in this setting. The aim of this study was to evaluate the efficacy, safety, and impact on quality of life (QoL) of THD on CINV following HEC.

Methods

Electronic databases were systematically searched for all randomized controlled trials (RCTs) in HEC using THD. The primary outcomes were complete response (CR) and no nausea, Secondary outcomes were the incidence of adverse events and QoL related indicators. We calculated risk ratios (RRs) and 95% confidence intervals (CIs) using a fixed-effects model. In the case of heterogeneity (I2≥50%), a random-effects model was performed.

Results

A total of 3168 patients were included from 34 RCTs. In terms of CR rate, THD plus 5-HT3 receptor antagonist (5-HT3RA) with or without dexamethasone (DEX) was significantly higher than 5-HT3RA with or without DEX in the acute phase (74.4% vs 67.4%; RR 1.10), delayed phase (70.6% vs 50.4%; RR 1.53), and overall phase (68.4% vs 53.4%; RR 1.28). In terms of no nausea rate, the THD group was also significantly higher than the control group in the acute phase (61.7% vs 55.5%; RR 1.12), delayed phase (50.5% vs 30.0%; RR 1.69), and overall phase (44.6% vs 29.9%; RR 1.50). There was no statistical difference in the incidence of fatigue, headache, diarrhea, rash, hepatorenal damage, and myelosuppression between those with and without THD. The incidence of increase in KPS scores, weight gain, appetite improvement, and sleep quality improvement were significantly higher with the addition of THD.

Conclusions

THD may be effective and safe for the prevention of CINV patients treated with HEC and may improve QoL.

Granisetron Extended-Release Subcutaneous Injection versus Palonosetron Infusion for CINV Prevention: Cost Comparison of Unscheduled Hydration

BACKGROUND

Granisetron extended-release subcutaneous (SC) injection is a novel formulation of granisetron for the prevention of acute and delayed chemotherapy-induced nausea and vomiting (CINV). Palonosetron is administered intravenously and is indicated for CINV prevention in acute and delayed phases after the use of moderately emetogenic chemotherapy (MEC) and in the acute phase after highly emetogenic chemotherapy (HEC). No data are available regarding the impact of SC granisetron on the cost of unscheduled hydration compared with other antiemetic drugs, specifically the older-generation palonosetron.

OBJECTIVE

To compare the costs of unscheduled hydration associated with breakthrough CINV after SC granisetron versus palonosetron administration in patients receiving MEC or HEC.

METHODS

This retrospective analysis was based on electronic medical records data from a single multicenter, community-based practice involving patients receiving MEC or HEC with a 3-drug antiemetic regimen, including a neurokinin-1 receptor antagonist, dexamethasone, and either SC granisetron or palonosetron. A cost-of-care analysis for SC granisetron and palonosetron was based on the maximum per-unit Medicare reimbursement amounts for the use of unscheduled hydration, administration of rescue antiemetic drugs, laboratory tests, and patient office evaluations.

RESULTS

A total of 182 patient records were evaluated, 91 for patients receiving SC granisetron and 91 receiving palonosetron. The mean per-patient cost of care related to unscheduled hydration in patients receiving HEC or MEC was significantly lower with SC granisetron ($296) than palonosetron ($837; P <.0001), including subset analysis of patients requiring additional care (SC granisetron [$691], N = 39; palonosetron [$1058], N = 72; P = .0260). The mean hydration costs per patient receiving HEC or MEC were lower with SC granisetron ($62) than with palonosetron ($253; P <.0001). The hydration costs per patient receiving only HEC were lower with SC granisetron ($66) than palonosetron ($280; P <.0001). The per-patient costs were lower when SC granisetron was administered than when palonosetron was administered as part of the antiemetic regimen, except for the cost of rescue antiemetic drug in patients receiving MEC. Fewer median unscheduled hydration therapies per patient were used with SC granisetron versus palonosetron (HEC, 3 vs 5; MEC, 2 vs 3).

CONCLUSION

The use of SC granisetron reduced the total per-patient costs of care associated with unscheduled hydration compared with palonosetron in patients receiving HEC or MEC for breakthrough CINV events.

Granisetron Extended-Release Subcutaneous Injection versus Palonosetron Infusion for CINV Prevention: Cost Comparison of Unscheduled Hydration

BACKGROUND

Granisetron extended-release subcutaneous (SC) injection is a novel formulation of granisetron for the prevention of acute and delayed chemotherapy-induced nausea and vomiting (CINV). Palonosetron is administered intravenously and is indicated for CINV prevention in acute and delayed phases after the use of moderately emetogenic chemotherapy (MEC) and in the acute phase after highly emetogenic chemotherapy (HEC). No data are available regarding the impact of SC granisetron on the cost of unscheduled hydration compared with other antiemetic drugs, specifically the older-generation palonosetron.

OBJECTIVE

To compare the costs of unscheduled hydration associated with breakthrough CINV after SC granisetron versus palonosetron administration in patients receiving MEC or HEC.

METHODS

This retrospective analysis was based on electronic medical records data from a single multicenter, community-based practice involving patients receiving MEC or HEC with a 3-drug antiemetic regimen, including a neurokinin-1 receptor antagonist, dexamethasone, and either SC granisetron or palonosetron. A cost-of-care analysis for SC granisetron and palonosetron was based on the maximum per-unit Medicare reimbursement amounts for the use of unscheduled hydration, administration of rescue antiemetic drugs, laboratory tests, and patient office evaluations.

RESULTS

A total of 182 patient records were evaluated, 91 for patients receiving SC granisetron and 91 receiving palonosetron. The mean per-patient cost of care related to unscheduled hydration in patients receiving HEC or MEC was significantly lower with SC granisetron ($296) than palonosetron ($837; P <.0001), including subset analysis of patients requiring additional care (SC granisetron [$691], N = 39; palonosetron [$1058], N = 72; P = .0260). The mean hydration costs per patient receiving HEC or MEC were lower with SC granisetron ($62) than with palonosetron ($253; P <.0001). The hydration costs per patient receiving only HEC were lower with SC granisetron ($66) than palonosetron ($280; P <.0001). The per-patient costs were lower when SC granisetron was administered than when palonosetron was administered as part of the antiemetic regimen, except for the cost of rescue antiemetic drug in patients receiving MEC. Fewer median unscheduled hydration therapies per patient were used with SC granisetron versus palonosetron (HEC, 3 vs 5; MEC, 2 vs 3).

CONCLUSION

The use of SC granisetron reduced the total per-patient costs of care associated with unscheduled hydration compared with palonosetron in patients receiving HEC or MEC for breakthrough CINV events.

Implementation of a clinical pharmacist-led service to optimize management of refractory chemotherapy-induced nausea and vomiting in adult hematology/oncology clinic

OBJECTIVE

Chemotherapy-induced nausea and vomiting (CINV) is a common and potentially debilitating adverse effect of chemotherapy. Refractory CINV can be particularly difficult to control. This report provides details on the implementation and evaluation of a pharmacist-led program for the management of refractory CINV in hematology and oncology clinics.

METHODS

A pharmacist-led program open to adult outpatients with refractory CINV was implemented at University of Wisconsin. Pharmacists conducted baseline and follow-up assessments, provided patient education, and started, discontinued, and/or adjusted antiemetics as clinically necessary for all enrolled patients. Retrospective chart review was used to describe the proportion of patients whose CINV improved through pharmacist intervention, effect of the program on antiemetic adherence, categorization of pharmacist interventions, and duration of patient enrollment.

RESULTS

Forty-six patients were enrolled between February 2019 and January 2020. Forty-one patients (89.1%) had an overall reduction in their nausea and vomiting from baseline. Eleven patients (23.9%) met criteria for nonadherence to prescribed antiemetics at baseline; all patients were adherent at unenrollment. A total of 111 pharmacist interventions were made. The most common intervention was addition of new breakthrough antiemetic. The least common intervention was dose escalation of a previously prescribed antiemetic. The average number of interventions made per patient was 2.5. On average, patients were enrolled in the program for 16.6 days and met with a pharmacist three times.

CONCLUSION

Implementation of this program standardized and streamlined pharmacist involvement with refractory CINV. Enrollment resulted in a measurable reduction in nausea and/or vomiting for patients with refractory CINV.

Chemotherapy-Induced Nausea and Vomiting in Breast Cancer Patients: A Multicenter Prospective Observational Study

Objective:

This study aimed to assess the occurrence of chemotherapy-induced nausea and vomiting (CINV) in acute phase (24 h after chemotherapy) and delayed phase (2–5 days after chemotherapy) after standard antiemetic therapy and to explore the risk factors of CINV in the acute and delayed phases.

Methods:

This prospective and observational study analyzed the data of 400 breast cancer patients scheduled for chemotherapy in two hospitals. The self-report survey was developed to assess the occurrence of CINV and their associated factors. On day 2 and day 6 of chemotherapy, CINV was evaluated by the Multinational Association of Supportive Care in Cancer Antiemetic Tool (MAT). The incidence of acute and delayed CINV was expressed as frequency and percentage.

Results:

Among 400 patients, 29.8% and 23.5% experienced acute and delayed CINV, respectively. Logistic regression analysis showed that the risk factors associated with acute CINV included pain/insomnia, history of CINV, and highly emetogenic chemotherapy. The history of motion sickness (MS), history of CINV, number of chemotherapy cycles completed, and the incidence of acute CINV were significant risk factors for delayed CINV (all P < 0.05).

Conclusions:

The results of this study are helpful for nurses to identify high-risk patients with CINV, formulate effective treatment plans, and reduce the incidence of CINV.

Low-dose olanzapine, sedation and chemotherapy-induced nausea and vomiting: a prospective randomized controlled study

Aims: Comparison of efficacy, safety and sedation between two doses of olanzapine in the control of chemotherapy-induced nausea and vomiting (CINV). Patients & methods: A prospective, randomized, double-blind, controlled study was conducted, enrolling 68 patients receiving a single-day cycle of high and moderately emetogenic chemotherapy. Patients received either of olanzapine 5 mg or 10 mg from day 1 through 3 in addition to ondansetron and dexamethasone. Control of CINV, nausea, sedation, quality of life (QoL) and adverse events were compared. Results: Nausea, emesis control and improvement of QoL were similar in both groups. Sedation severity was 133% higher with 10 mg olanzapine. Conclusions: Lower dose olanzapine is effective to control CINV with significantly reduced sedation.

Intergenerational comparison of 5-HT3RA in the prevention of chemotherapy-induced nausea and vomiting in gastric cancer patients receiving cisplatin-based chemotherapy: an observational study using a Japanese administrative claims database

PURPOSE

In chemotherapy-induced nausea and vomiting (CINV), the superiority of the second-generation 5-hydroxytryptamine-3 receptor antagonist (5-HT₃RA) over the first-generation 5-HT₃RA is shown in the delayed emesis in cycle 1. We evaluate the antiemetic efficacy in real-world clinical practice that has not been sufficiently investigated in clinical trials.

METHODS

We included patients who were diagnosed with gastric cancer between April 2012 and June 2017 from the medical claims databases and were treated with cisplatin (≥ 50 mg/m²) and standard antiemetic therapy (5-HT₃RA + neurokinin-1 receptor antagonist [NK1RA] + dexamethasone). We compared the second-generation 5-HT₃RA (2nd group) and the first-generation 5-HT₃RA (1st group) groups to evaluate the additional antiemetic drug as the CINV event.

RESULTS

In total, 3798 patients were extracted; 1440 and 2358 patients were included in the 1st and 2nd groups, respectively. The clinical and demographic characteristics did not differ between the groups. In the overall (days 1-6) in cycle 1, 51.7% and 44.3% of patients in the 1st and 2nd groups, respectively, had a CINV event. In the acute phase (days 1-2), 38.7% and 30.2% and in the delayed phase (days 3-6), 35.8% and 32.1% of patients in the 1st and 2nd groups, respectively, had a CINV event. Furthermore, the CINV event trend was the same as in cycles 1 to 5.

CONCLUSION

The proportion of CINV events in the 2nd group was smaller than that in the 1st group at any cycle. These findings may suggest consistent antiemetic efficacy of second-generation 5-HT₃RA throughout the cycle.

Clinically established biodegradable long acting injectables: An industry perspective

Long acting injectable formulations have been developed to sustain the action of drugs in the body over desired periods of time. These delivery platforms have been utilized for both systemic and local drug delivery applications. This review gives an overview of long acting injectable systems that are currently in clinical use. These products are categorized in three different groups: biodegradable polymeric systems, including microparticles and implants; micro and nanocrystal suspensions and oil-based formulations. Furthermore, the applications of these drug delivery platforms for the management of various chronic diseases are summarized. Finally, this review addresses industrial challenges regarding the development of long acting injectable formulations.

Orthosteric and Allosteric Activation of Human 5-HT3A Receptors

The serotonin type 3 receptor (5-HT₃) is a ligand-gated ion channel that converts the binding of the neurotransmitter serotonin (5-HT) into a transient cation current that mediates fast excitatory responses in peripheral and central nervous systems. Information regarding the activation and modulation of the human 5-HT₃ type A receptor has been based only on macroscopic current measurements because of its low ion conductance. By constructing a high-conductance human 5-HT₃A receptor, we here revealed mechanistic information regarding the orthosteric activation by 5-HT and by the partial agonist tryptamine, and the allosteric activation by the terpenoids, carvacrol, and thymol. Terpenoids potentiated macroscopic currents elicited by the orthosteric agonist and directly elicited currents with slow-rising phases and submaximal amplitudes. At the single-channel level, activation by orthosteric and allosteric agonists appeared as openings in quick succession (bursts) that showed no ligand concentration dependence. Bursts were grouped into long-duration clusters in the presence of 5-HT and even longer in the presence of terpenoids, whereas they remained isolated in the presence of tryptamine. Kinetic analysis revealed that allosteric and orthosteric activation mechanisms can be described by the same scheme that includes transitions of the agonist-bound receptor to closed intermediate states before opening (priming). Reduced priming explained the partial agonism of tryptamine; however, equilibrium constants for gating and priming were similar for 5-HT and terpenoid activation. Thus, our kinetic analysis revealed that terpenoids are efficacious agonists for 5-HT₃A receptors. These findings not only extend our knowledge about the human 5-HT₃A molecular function but also provide novel insights into the mechanisms of action of allosteric ligands, which are of increasing interest as therapeutic drugs in all the superfamily.

High-resolution structures of multiple 5-HT3AR-setron complexes reveal a novel mechanism of competitive inhibition

Serotonin receptors (5-HT3AR) play a crucial role in regulating gut movement, and are the principal target of setrons, a class of high-affinity competitive antagonists, used in the management of nausea and vomiting associated with radiation and chemotherapies. Structural insights into setron-binding poses and their inhibitory mechanisms are just beginning to emerge. Here, we present high-resolution cryo-EM structures of full-length 5-HT3AR in complex with palonosetron, ondansetron, and alosetron. Molecular dynamic simulations of these structures embedded in a fully-hydrated lipid environment assessed the stability of ligand-binding poses and drug-target interactions over time. Together with simulation results of apo- and serotonin-bound 5-HT3AR, the study reveals a distinct interaction fingerprint between the various setrons and binding-pocket residues that may underlie their diverse affinities. In addition, varying degrees of conformational change in the setron-5-HT3AR structures, throughout the channel and particularly along the channel activation pathway, suggests a novel mechanism of competitive inhibition.

Selinexor in patients with relapsed or refractory diffuse large B-cell lymphoma (SADAL): a single-arm, multinational, multicentre, open-label, phase 2 trial

BACKGROUND

Relapsed or refractory diffuse large B-cell lymphoma (DLBCL) is an aggressive cancer with a median overall survival of less than 6 months. We aimed to assess the response to single-agent selinexor, an oral selective inhibitor of nuclear export, in patients with relapsed or refractory DLBCL who had no therapeutic options of potential clinical benefit.

METHODS

SADAL was a multicentre, multinational, open-label, phase 2b study done in 59 sites in 19 countries. Patients aged 18 years or older with pathologically confirmed diffuse large B-cell lymphoma, an Eastern Cooperative Oncology Group performance status of 2 or less, who had received two to five lines of previous therapies, and progressed after or were not candidates for autologous stem-cell transplantation were enrolled. Germinal centre B-cell or non-germinal centre B-cell tumour subtype and double or triple expressor status were determined by immunohistochemistry and double or triple hit status was determined by cytogenetics. Patients received 60 mg selinexor orally on days 1 and 3 weekly until disease progression or unacceptable toxicity. The study was initially designed to evaluate both 60 mg and 100 mg twice-weekly doses of selinexor; however, the 100 mg dose was discontinued in the protocol (version 7.0) on March 29, 2017, when an improved therapeutic window was observed at 60 mg. Primary outcome was overall response rate. The primary outcome and safety were assessed in all patients who received 60 mg selinexor under protocol version 6.0, or enrolled under protocol versions 7.0 or higher and received at least one dose of selinexor. This trial is registered at ClinicalTrials.gov, NCT02227251 (active but not enrolling).

FINDINGS

Between Oct 21, 2015, and Nov 2, 2019, 267 patients were randomly assigned, with 175 allocated to the 60 mg group and 92 to the discontinued 100 mg group. 48 patients assigned to the 60 mg group were excluded due to enrolment before version 6.0 of the protocol; the remaining 127 patients received selinexor 60 mg and were included in analyses of primary outcome and safety. The overall response rate was 28% (36/127; 95% CI 20·7-37·0); 15 (12%) achieved a complete response and 21 (17%) a partial response. The most common grade 3-4 adverse events were thrombocytopenia (n=58), neutropenia (n=31), anaemia (n=28), fatigue (n=14), hyponatraemia (n=10), and nausea (n=8). The most common serious adverse events were pyrexia (n=9), pneumonia (n=6), and sepsis (n=6). There were no deaths judged as related to treatment with selinexor.

INTERPRETATION

Single-drug oral selinexor induced durable responses and had a manageable adverse events profile in patients with relapsed or refractory DLBCL who received at least two lines of previous chemoimmunotherapy. Selinexor could be considered a new oral, non-cytotoxic treatment option in this setting.

FUNDING

Karyopharm Therapeutics Inc.

Gastroparesis: a turning point in understanding and treatment

Gastroparesis is defined by delayed gastric emptying (GE) and symptoms of nausea, vomiting, bloating, postprandial fullness, early satiety and abdominal pain. Most common aetiologies include diabetes, postsurgical and postinfectious, but in many cases it is idiopathic. Clinical presentation and natural history vary by the aetiology. There is significant morbidity and healthcare utilisation associated with gastroparesis. Mechanistic studies from diabetic animal models of delayed GE as well as human full-thickness biopsies have significantly advanced our understanding of this disorder. An innate immune dysregulation and injury to the interstitial cells of Cajal and other components of the enteric nervous system through paracrine and oxidative stress mediators is likely central to the pathogenesis of gastroparesis. Scintigraphy and 13C breath testing provide the most validated assessment of GE. The stagnant gastroparesis therapeutic landscape is likely to soon see significant changes. Relatively newer treatment strategies include antiemetics (aprepitant), prokinetics (prucalopride, relamorelin) and fundic relaxants (acotiamide, buspirone). Endoscopic pyloromyotomy appears promising over the short term, especially for symptoms of nausea and vomiting. Further controlled trials and identification of the appropriate subgroup with pyloric dysfunction and assessment of long-term outcomes are essential. This review highlights the clinical presentation, diagnosis, mechanisms and treatment advancements for gastroparesis.

Molecular mechanism of setron-mediated inhibition of full-length 5-HT3A receptor

Serotonin receptor (5-HT_3AR) is the most common therapeutic target to manage the nausea and vomiting during cancer therapies and in the treatment of irritable bowel syndrome. Setrons, a class of competitive antagonists, cause functional inhibition of 5-HT_3AR in the gastrointestinal tract and brainstem, acting as effective anti-emetic agents. Despite their prevalent use, the molecular mechanisms underlying setron binding and inhibition of 5-HT_3AR are not fully understood. Here, we present the structure of granisetron-bound full-length 5-HT_3AR solved by single-particle cryo-electron microscopy to 2.92 Å resolution. The reconstruction reveals the orientation of granisetron in the orthosteric site with unambiguous density for interacting sidechains. Molecular dynamics simulations and electrophysiology confirm the granisetron binding orientation and the residues central for ligand recognition. Comparison of granisetron-bound 5-HT_3AR with the apo and serotonin-bound structures, reveals key insights into the mechanism underlying 5-HT_3AR inhibition.

Alterations of colonic sensitivity and gastric dysmotility after acute cisplatin and granisetron

BACKGROUND

Cisplatin is a highly emetogenic antineoplastic drug and induces peripheral neuropathy when given in cycles. Granisetron, a 5-HT₃ antagonist, is clinically used to prevent chemotherapy-induced nausea/emesis and abdominal pain in irritable bowel syndrome. The effects of cisplatin on visceral sensitivity and those of granisetron in the context of cancer chemotherapy are not well known.

METHODS

Adult male Wistar rats received two intraperitoneal injections 30 minutes apart: granisetron (1 mg kg^-1 )/vehicle and cisplatin (6 mg kg^-1 )/vehicle. Thereafter, nausea-like behavior was measured as bedding intake for 4 hours, and gastric dysmotility was measured radiographically for 8 hours. Gastric weight and size were determined ex vivo and samples of the forestomach, corpus, ileum, and colon were obtained for histological analysis at 4 and 30 hours after cisplatin/vehicle. Visceral sensitivity was measured as abdominal contractions in response to mechanical intracolonic stimulation 2 hours after cisplatin/vehicle.

KEY RESULTS

Cisplatin-induced bedding intake and gastric dysmotility, and granisetron blocked these effects, which occurred in the absence of frank mucositis. Visceral sensitivity was reduced to a similar extent by both drugs alone or in combination.

CONCLUSIONS AND INFERENCES

Cisplatin-induced bedding intake and gastric dysmotility were blocked by granisetron, confirming the involvement of serotonin acting on 5-HT₃ receptors. Unexpectedly, visceral sensitivity to colonic distension was reduced, to the same extent, by cisplatin, granisetron, and their combination, suggesting important mechanistic differences with nausea and gastric dysmotility that warrant further investigation.

Natural Negative Allosteric Modulators of 5-HT₃ Receptors

Chemotherapy-induced nausea and vomiting (CINV) remain the most common and devastating side-effects associated with cancer chemotherapy. In recent decades, several lines of research emphasize the importance of 5-hydroxytryptamine3 (5-HT3; serotonin) receptors in the pathogenesis and treatment of CINV. 5-HT₃ receptors are members of ligand-gated ion channels that mediate the rapid and transient membrane-depolarizing effect of 5-HT in the central and peripheral nervous system. These receptors play important roles in nausea and vomiting, as well as regulation of peristalsis and pain transmission. The development of antagonists for 5-HT₃ receptor dramatically improved the treatment of CINV in cancer patients. In fact, the most common use of 5-HT₃ receptor antagonists to date is the treatment of nausea and vomiting. In recent years, there has been an increasing tendency to use natural plant products as important therapeutic entities in the treatment of various diseases. In this article, we examined the results of earlier studies on the actions of natural compounds on the functional properties of 5-HT₃ receptors. It is likely that these natural modulators of 5-HT₃ receptors can be employed as lead structures for the synthesis of therapeutic agents for treating CINV in future clinical studies.