I know nothing about the antihistamine. I recommend doing a site search for both meds, and using the drug interaction link in the Resources Compilation sticky thread for the two medicines together.
Propanolol has been discussed on the forum in the past as you'll find from doing a search. A minimum of 8g is recommended for a propanolol OD, and adding a calcium channel blocker will increase the effects.
Edit: Search Odanestron as well. You'll need an antiemetic, which is not the same as an antinausea medication.