Here are some key books in the area of Business Ethics:
A Companion to Bioethics (Blackwell Companions to Philosophy), edited by Helga Kuhse, Peter Singer (2001) [An excellent anthology.]
Principles of Biomedical Ethics, 6th edn., by Tom Beauchamp and James Childress. [This is effectively the textbook of the field of Bioethics.]
Doing Right: A Practical Guide to Ethics for Medical Trainees and Physicians, by Philip C. Hébert [A smart, practically-minded text aimed at physicians and physicians-in-training.]
Ethics & Issues in Contemporary Nursing (Cdn Edition), by Burkhardt, Nathaniel & Walton [Link is to Amazon.ca]
Oxford Textbook of Clinical Research Ethics, by Emanuel et al.
Stakes and Kidneys: Why Markets in Human Body Parts are Morally Imperative, by James Stacey Taylor [A good example of how careful argumentation can make an implausible thesis seem entirely reasonable.]
No Margin, No Mission: Health Care Organizations and the Quest for Ethical Excellence, by Steven D. Pearson, James Sabin, and Ezekiel J. Emanuel