Freakdog (2008)

A young doctor in a hospital administers a powerful and untested cocktail of drugs to a coma victim. But instead of curing him, it triggers a powerful "out-of-body" experience and enables the patient, a depraved and dangerous loner, to inhabit other people's bodies and, through them, take revenge on the bullying medical students who were accidentally responsible for his condition. The doctor, who was herself a part of this group, is also targeted, and as her colleagues are singled out and relentlessly picked off, she realises that she can trust no one, friend or stranger, as this comatose killer moves in and out of bodies at will, getting ever closer as his murderous supernatural powers increase.