Mr. S., a 68-year-old retired bus driver, has begun outpatient chemotherapy after a recent diagnosis of lung cancer. He has recovered well from a right lung lobectomy, the incisions are well healed,...

Mr. S., a 68-year-old retired bus driver, has begun outpatient chemotherapy after a recent diagnosis of lung cancer. He has recovered well from a right lung lobectomy, the incisions are well healed, and he is now physically and emotionally ready for a 3-month regimen of chemotherapy. The premedication orders call for a variety of drugs, including granisetron (Kytril). Mr. S. has a prescription for oral ondansetron (Zofran) for use at home. 1. What is the mechanism of action of granisetron that makes it effective in the management of chemotherapy-induced nausea and vomiting? 2. What important patient teaching points should you emphasize to Mr. S. about the ondansetron? 3. After 2 weeks of therapy, the oncologist discontinues the ondansetron because Mr. S. complains that it does nothing to help the nausea and vomiting. Mr. S. receives a prescription for dronabinol but expresses concern, exclaiming, “There’s marijuana in that pill!” What would you explain to Mr. S.?