Books are worse than cars in the resale world. It is so disappointing.
I found a 4th edition that sold (not asking but sold price) for 7.88.
A second edition may fetch 1/2 that, but unfortunately I did not see any examples of listed or sold at the moment. Finding an example of one that sold would give us today's actual market value.
It is probably worthless. It would only have value if it were an antique
Occasionally older school books are worth a few dollars but as a general rule, medical books do not have value. Not always the case but most of the time these books are constantly changing and students have to have the latest editions.
Once in a while someone (not a student) may buy an older medical book but I would not wish to count on this happening.
I have had to discard beautiful (expensive!) books that my children used in college and it is not easy to see them go in the recycle bin.
You can research any of your books that you are curious about by using Google and the title of the book. You'll have to check editions and publication dates but this will tell you if it is worth saving.
eBay and Amazon are the largest book selling sites but there are other sites that specialize in Medical books.
You can Google sell medical books and find some of these sites.
Medical book and other types of school books normally are hard to sell back because they update them so often. The books cost so much to buy when new and by the end of the school term they are worthless and hard to sell back. Your book does not hold much value as it is now and can be used as a reference book or just a book to look up something you are interested in.