5 WARNINGS AND PRECAUTIONS
5.1 Hypersensitivity Reactions
Hypersensitivity reactions, including anaphylaxis and anaphylactic shock, have been reported with administration of Palonosetron HCl Injection [see Adverse Reactions (6.2)]. These reactions occurred in patients with or without known hypersensitivity to other 5-HT3 receptor antagonists. If hypersensitivity reactions occur, discontinue Palonosetron HCl Injection and initiate appropriate medical treatment. Do not reinitiate Palonosetron HCl Injection in patients who have previously experienced symptoms of hypersensitivity [see Contraindications (4)].
5.2 Serotonin Syndrome
The development of serotonin syndrome has been reported with 5-HT3 receptor antagonists. Most reports have been associated with concomitant use of serotonergic drugs (e.g., selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors, mirtazapine, fentanyl, lithium, tramadol, and intravenous methylene blue). Some of the reported cases were fatal. Serotonin syndrome occurring with overdose of another 5-HT3 receptor antagonist alone has also been reported. The majority of reports of serotonin syndrome related to 5-HT3 receptor antagonist use occurred in a post-anesthesia care unit or an infusion center.
Symptoms associated with serotonin syndrome may include the following combination of signs and symptoms: mental status changes (e.g. agitation, hallucinations, delirium, and coma), autonomic instability (e.g., tachycardia, labile blood pressure, dizziness, diaphoresis, flushing, hyperthermia), neuromuscular symptoms (e.g., tremor, rigidity, myoclonus, hyperreflexia, incoordination), seizures, with or without gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea). Patients should be monitored for the emergence of serotonin syndrome, especially with concomitant use of Palonosetron HCl Injection and other serotonergic drugs. If symptoms of serotonin syndrome occur, discontinue Palonosetron HCl Injection and initiate supportive treatment. Patients should be informed of the increased risk of serotonin syndrome, especially if Palonosetron HCl Injection is used concomitantly with other serotonergic drugs [see Drug Interactions (7.1)].