A 15 year old male arrives to the outpatient clinic for his…

A 15 year old male arrives to the outpatient clinic for his chemotherapy infusion.  The teenager begins vomiting as soon as he gets into his room and sees the nurse who will be accessing his Port-a-cath to start the infusion.  What medication would be the BEST choice for this patient at this time and what is the rationale for selecting this medication?   (short answer please)