It would help to know the geographic area of interest so that responses will be more specific and helpful. I would start with a "History of Medicine in 18th century (country)" and collect some names of prominent physicians. Often if they are mentioned in an historical study it's because they wrote something. A search for those physicians mentioned should render some results. Also, you should search for 18th century educational reform plans in the geographic area of your interest. Reforming medical education was a prevalent focus of the Enlightenment scholars. Jose Celestino Mutis in New Granada (Colombia), for example wrote several study plans for medicine contrasting the outdated methods and topics of "the Ancients" with the then modern approach to medicine of the Enlightenment scholars. You may also want to check the journals of the learned societies for 18th century studies; occasional articles on the topic appears in them. Good and interesting topic, by the way. I wish you luck. If I can be of further help, let me know.
As I recently read your question, no specific article of bibliography came in my mind, but I immediately thought of a very interesting treatise of the eighteenth century in the military field (the domain I am specialized in):
John PRINGLE (Physician-General to his Majesty’s Forces employed abroad during the late War), Observations on the Diseases of the Army, in Camp and Garrison. In three Parts. With an Appendix, containing some Papers of Experiments, read at several Meetings of the Royal Society. London, A. Millar, 1753 (second edition).
This treatise is available on the Internet, on google.books.