Can a bachelors degree in nursing be a premedical degree?

It really depends on the actual classes you took to get a BA in nursing. I have a friend who was a dance major at Loyola Marymount University and went to Georgetown University Medical School. She made sure to take all the individual pre-requisite classes for medical school and scored competitively on the MCAT.

I would look at all the individual pre-requisite courses for medical schools and see how they match up to the individual classes you took to get your BA in nursing. Then you will have a good idea about how many classes you will need to take to qualify to be a med school candidate or if you are qualified already.

Not really.

The problem is, the course versions of chemistry, physics and biology that are part of nursing curricula are not compatible with the requirements set by most med schools. You will wind up repeating a lot of coursework.

Imagine having to take two semesters of anatomy/physiology with lab, then having to take two more semesters of introductory bio. Or doing a semester of remedial physics, then having to retake a full year of it with calculus. Also, nursing chemistry combines biochem, remedial o-chem (as if o-chem could be remedial, but I digress) and some general chem. But as a pre-med, then you'd have to take the harder versions of those courses separately on top of that.

Frankly, the redundancy would be a complete waste of your time. If you wanted to do a BSN, I'd recommend you apply that coursework to a graduate program as a physician assistant. Grad-level PA programs have the same pre-reqs as nursing programs.

FYI for pre-meds Baccalaureate coursework must include:
1 year general chem (with lab)
1 year organic chem (with lab)
1 year general biology (with lab)
1 year intro. physics (with lab)
1 year English
1 year calculus
Suggested coursework includes: psychology, statistics, biochemistry, humanities