Hi Zena,
I don`t know much about the MTX injections, but I had a similar problem a few years ago with my humira injections. They have to be stored in the fridge, and I was concerned after a fairly lengthy power cut, whether they would still be valid. I phoned my provider - Healthcare at Home - who got one of their pharmacists to speak to me. She asked me how long the power had been off, had we needed to open the fridge door regularly etc., then said the epipens would be OK, but if the power went off again, while the same batch was in use I would have to let them know, as they would need to be replaced. I didn`t have anyone nearby whose fridge I could "borrow," as all my neighbours, and my dad and son were all on the same electricity circuit.
If your injections come from H@H they will certainly advise, otherwise perhaps either your local pharmacist or the hospital pharmacy might help, or your rheumy nurse.
Sorry if this is a bit long-winded!
Kathleen x