bdpy, I think it is a "DMARD" which is quite a powerful drug, that has the ability to cause a whole host of potential adverse effects.
I'm not an AME, but I'm guessing that that the authorities will be interested in several things: Is the underlying condition stable ? Has it resulted in incapacitating episodes ? How often do exacerbation's occur ? What was the result of those exacerbations ? (eg hospitalisation/time off work)
The medicine itself can be quite toxic, to some people. The fact that you are stable goes in your favour. I'm guessing that you are carefully monitored, in terms of blood tests. Your quack should quite easily be able to print off your results. LFT's, U+E's and FBC's (white cells and neutrophils) will be of interest to the AME's. Try and print out the "reference ranges" (limits of normal) as AME's, despite being well educated, sometimes need you to lead them to the answers !
If all are stable, then I suspect you have nothing to worry about.