I have always liked Lippincott's guides...they have one for just about any nursing subject. Most recently I bought How to Get an A in (put in the subject--med/surg, mental health, mother/child, etc.) There was a different series about 5 years ago, I have those books also, but don't see them published by Lippincott. Those books are very good and will give you the basics of the program...although you will still need to study your course's books. I have used them to study for the NCLEX. Lippincott should have a guide to pharmacology.
I bought my books from Amazon and I was able to see reviews from those who bought the book. You want to go to your college's bookstore or a large bookstore to actually look through the book you are considering buying...but buy the book online, used if you can. It will save you $'s.
Get a good NCLEX book that has a condensed explanation of each section--something like a quick and dirty review at the beginning of each seciton (some NCLEX books do not have this review; I don't remember which NCLEX books offer this benefit). Read the NCLEX book, start answering the questions, and check your answers in the back of the book. If you got a good book, it will not only give you the answer, but the rationale why the answer is correct and why the other answers are incorrect.
I found that having more than one book on a subject helped me understand what I was learning. Best to you