I purchased a physicians desk reference book and a nurses guide to drugs based on the recommendation of a nurse friend. I also have numerous other medical references. My goal is to have a basic level of knowledge myself and supplies for most basic problems. Perhaps if its something serious there will be someone around who can use those items to help.
As you say its unrealistic to develop this level of knowledge as a hobby.
One thing you need to understand is that the PDR is basically a reprint of what the drug company puts in the box with the meds. It is a good basic guide but cross check what you read there.