Premed major trying to learn a little bit ahead,looking: books on cells in the brain vs.manufactured chemical?

I doubt you will find any textbooks that cover the mechanism of action of that drug and only that drug. However, if you are interested in Neuroscience (which is basically the subject that deals with antidepressants, etc...) then I strongly recommend Stahl's Essential Psychopharmacology by Stephen M. Stahl. The book goes over all of the major concepts in neurobiology in a very easy to understand matter. A few medical schools use this book to teach neuroscience and having read it myself, I think it does a pretty good job. Hope this helps.