What are the requirements to become a physicians istant from having engineering and management degree?

I have BS in Interdisciplinary Engineering and management (my university's way saying industrial engineering and management) I have taken electrical and material science cles, chemistry one and two and physics one and two as well as calc 1-3 and diff eq. part of my electives I took some basic biology. I realize I need some organic chemistry courses at least. But what else would I have to do to get a Physician's istant Degree? And which would be better an Nurse Practitioner or Physician's istant in the long run to becoming a M.D.?