I've been given the choice of taking either 32 mg methylprednisolone at 12 and 2 hours or prednisolone 50mg at 13, 7, and 1 hr pre mri for a contrast allergy. how are these equivalent if 150mg of prednisone= 120mg of methylprednisolone?

Although both are steroids, they are different medicines so the dosing is different. But, the effect would be the same as both would help prevent a reaction to the contrast. I would choose whichever is easier for you! Good luck with your MRI!

That is a good question, and you are correct in noticing these two protocols are not exactly equivalent. Part of the issue stems from the lack of a "perfect" dose for steroid administration. I've looked and don't believe there is a great study that has rigorously tested all possible combinations and it often depends on which doses are given in common practice. Note one is IV, the other is oral.