Using the drugs.com drug interaction checker all of these drugs should be fine with vitamin C.
As for other interactions I'm sure you know Remicade & Azathioprine both suppress the immune system further.
Taking Synthroid & Colestod too close together can interfere with Synthroid absorption and effectiveness.
Pentasa may increase the effects of Azathioprone.
So in answering your question I found out more so just sharing but vitamin c is a go. Feel better.