I've seen a post like this so many times, i feel like those that allow themselves to fail classes without help or not withdrawing from the course in time, is going to have a hard time in any professional school in the future (sorry for the generalization becuz i don't know your background story). That saying, professional school takes a lot of dedication and focus and esp. hard work and time management. In addition, if you're having a hard time with your class load, lessen it. It's always better to end the semester strong than try to fix your GPA in the future.
Needless to say: a failing grade in any pharmacy/med pre-reqs is unacceptable. Some schools will not accept anything lower than a C as their minimum. AND you have to remember that even if you do end up retaking it, some schools will hold that against you in the admission process because your first grade was a D/F (or lower than a C). Retaking any pre-req that was lower than a C to begin with does not look good on your app.
Good luck, i hope everything works out