Chemical drugs not only kill tumour cells but also induce oxidative stress, inflammation, apoptosis, and necrosis in the gastrointestinal tract [16]. Neurotransmitters such as substance P, dopamine, and serotonin are subsequently released by enterochromaffin cells and bind to receptors, including 5-HT3 and NK1, which can activate the emetic reflex and induce nausea and vomiting [17]. Therefore, the 5-HT3 receptor antagonist ondansetron effectively inhibited chemotherapy-induced nausea and vomiting. According to a previous study, the rate of no acute nausea or vomiting was 75% in the 81 patients who received 8 mg ondansetron plus dexamethasone orally prior to receiving chemotherapy with a moderate emetic risk; moreover, the incidence of grade 3 chemotherapy-induced nausea and vomiting was 1% [18]. Another study revealed that in glioma patients who received adjuvant temozolomide, 8 mg of ondansetron on days 1–5 resulted in a complete control (defined as no nausea, vomiting or antiemetic rescue medication) rate of 54.5% [19]. The current study revealed that the complete response rate of vomiting was 96.9%, and the no nausea rate was 96.3%, which were numerically higher than those reported in previous studies [18, 19]. The possible explanations are as follows. (1) The current study used ondansetron orally soluble pellicles, which can be easily swallowed [14]. Considering that some patients might have difficulty swallowing tablets, including those encountering anticipatory nausea and vomiting or those with head and neck tumours, orally soluble pellicles of ondansetron might be easier to swallow and reduce the risk of improper administration. (2) In the present study, the dose of ondansetron orally soluble in pellicles was 24 mg, which was higher than that used in previous studies [18, 19]. The current guidelines generally recommend a combination regimen for preventing chemotherapy-induced nausea and vomiting, including a 5-HT3-receptor antagonist, an NK1-receptor antagonist, and dexamethasone, with or without olanzapine (depending on the emetogenicity of chemotherapy) [20, 21]. The dose of ondansetron in the recommended combination regimen is 8 mg orally or 0.15 mg/kg intravenously injected prior to chemotherapy [20, 21]. The current study revealed that 24 mg ondansetron in the form of orally soluble pellicles could effectively prevent chemotherapy-induced nausea and vomiting, which provides potential evidence for alternative regimens to prevent chemotherapy-induced nausea and vomiting.

The results of the present study revealed that age > 65 years was associated with a lower possibility of achieving major efficacy of vomiting in patients receiving ondansetron via orally soluble pellicles for the prevention of nausea and vomiting induced by chemotherapy with a moderate-to-high emetic risk. However, several studies have shown that older patients have a lower risk of chemotherapy-induced nausea and vomiting [22, 23], which contradicts our findings. A possible explanation is that the sample size of this study was relatively small. Thus, the findings of this study could be affected by occasional cases. Our data also revealed that CDDP was associated with a lower possibility of achieving major nausea. A possible explanation is that CDDP is considered a highly emetogenic chemical [8]. Therefore, 24 mg of ondansetron orally soluble pellicles might be insufficient to prevent chemotherapy regimen-induced nausea and vomiting in these patients. Consequently, a combination regimen, such as the addition of olanzapine, should be considered to further prevent nausea and vomiting in these patients. Further studies could also consider adjusting the usage and dosage of ondansetron based on the emetic risk of chemotherapy to improve the prevention of nausea and vomiting induced by chemotherapy with a moderate-to-high emetic risk.

The most commonly reported adverse events of ondansetron are fatigue, headache, and transient increases in liver function indices [24,25,26,27]. Most studies have reported that administering ondansetron to prevent chemotherapy-induced nausea and vomiting is generally safe and tolerable [24,25,26,27]. In the present study, the most commonly occurring adverse events were elevated levels of alanine transaminase, elevated levels of aspartate transaminase, and fatigue. However, these adverse events were more likely to be associated with the usage of chemotherapy, rather than ondansetron. Constipation, a common adverse event related to ondansetron, was observed in three patients in this study. Moreover, most adverse events were tolerable and manageable. These data indicate the safety of ondansetron orally soluble pellicles for preventing nausea and vomiting induced by chemotherapy drugs with a moderate-to-high emetic risk.

Several limitations to the current study should be noted. First, this study was single-armed, and the efficacy and safety of ondansetron orally soluble pellicles should be further verified by randomized controlled trials. Second, the relatively insufficient sample size might have impaired the statistical power of the current study. Third, in addition to chemotherapy, radiotherapy and surgical resection can also induce nausea and vomiting. Therefore, the efficacy of ondansetron orally soluble pellicles for preventing radiotherapy- and surgical resection-induced nausea and vomiting should be further explored. Fourth, the gender was imbalanced in this study. The potential reason was that the majority of cancer type was lung cancer and gastrointestinal cancer, which were more likely to affect males. Although the association analyses showed that gender was not associated with the achievement of major efficacy of nausea or vomiting, studies should consider to include patients with a balanced gender to verify the effect of ondansetron orally soluble pellicles.

Conclusively, ondansetron orally soluble pellicles effectively prevent nausea and vomiting in patients with malignant tumours who receive chemotherapy drugs with a moderate-to-high emetic risk. This preventive treatment was also found to be safe. However, further randomized, controlled trials with larger sample sizes are needed for verification.