It depends a bit on what you're looking for. A text used for my undergrad "Biomedical Ethics" course was _Intervention and Reflection/Basic Issues in Medical Ethics_, 5th ed., by Ronald Munsen, 1996. The case studies are great. (I am selling this book due to a new required text being used, which I like less, but need cash; send me a private message if interested.)
My course now uses _Resolving Ethical Dilemmas/A guide for Clinicians_ by Bernard Lo. It's more like a manual, which is sort of useful but offers less for reflection on your own. The AMA also puts out its of Code of Medical Ethics, a softbound book, prepared by their Council on Ethical and Judicial Affairs. It is not very readable, but is clear in delineating the guidelines for US physicians and the sources they used to help determine this. Good luck in your search!
