My medical school class has members from a variety of different allied health professions. We have a PA, several RNs, a DC, and some others.
Some of these students (at my school, University of New England) were allowed to test out of certain classes because they had taken them before, but the review of their academic credentials was apparently quite rigorous.
It will likely depend on the medical school, and the level of your previous coursework. At UNE, for example, the Gross Anatomy class for PAs is far less demanding than the course for medical students, so PAs are usually out of luck in that regard.
Best of luck to you...
