 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  canister. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.The uses of Ondansetron HCl (PF) Injection: This medication is used alone or with other medications to prevent nausea and vomiting caused by cancer chemotherapy. It is also used to prevent and treat nausea and vomiting after surgery. It works by blocking one of the body's natural substances (serotonin) that causes vomiting. How to use Ondansetron Hcl (PF) 4 Mg/2 Ml Injection Solution To prevent nausea from chemotherapy, ondansetron is mixed in a solution and given by injection into a vein as directed by your doctor, usually over 15 minutes. This drug is usually started 30 minutes before your chemotherapy treatment begins. Do not give this medication any faster than recommended or take more than the recommended dose because this may increase the chance of serious side effects such as blurred vision or slowed/irregular heartbeat. The usual maximum single dose is 16 milligrams. Older adults are usually prescribed a lower dose to decrease the risk of side effects. Depending on the type of chemotherapy treatment </s>