I will tell you how my daughter has fared with the drugs she has taken that you listed. The ones I do not talk about were never taken by her. Everyone reacts differently to these drugs, so just letting you know how she reacted to them.
Hydrocodone- She feels it is not very effective alone, but used with Morphine it can be effective for pain. Her pain is not as severe now so she only takes long acting Morphine 2X daily and fast acting Morphine for any breakthrough pain maybe once or twice a week.
Zofran- Gave her migraine like headaches. She takes Compazine and Ativan for nausea and they both work well. Ativan is also for anxiety.
I would let your Dad eat whatever he is hungry for, no matter how much he does or doesn't eat. After Lauren has chemo, she likes bland comfort food like chicken noodle soup, creamed chicken, rice, mashed potatoes, oatmeal. She also has a little trick that if she gets nauseous, she chews spearmint gum and it usually settles her stomach.
I hope this helps. My best to you and your Dad.
Hoping for a miracle for my daughter, Lauren.
My comments, suggestions, and opinions are based on my experience as a caretaker for my daughter, Lauren and from reading anything I can get my hands on about Cholangiocarcinoma. Please consult a physician for professional guidance.