I'm going to tell a deep dark secret about the pharmacy school prerequisites:
"The hardest part of pharmacy school is getting in, not staying in." The modern curriculum for pharmacy should NOT be topically harder than the prerequisites, merely an extension of them.
The current state of the prerequisites to the major is meant to ensure that at least the candidate is trainable:
1. GChem, Physics, Calculus - Can the candidate do basic problem solving and use information for specific purposes (and weed out unnecessary information)?
2. OChem - Can the candidate understand, abstract, and apply (seemingly) arbitrary rules in novel ways?
3. English, Comm - Can the candidate write and speak in common English (this is one where I think we need to look at again seriously at ACPE, for any of you who've been on the opposite side of a phone conversation with an impossible-to-understand accent or diction)?
4. Analytical/Instrumental Analysis (if still required) - Is the candidate careful enough and neat enough to NOT endanger others in the hood?
5. Foreign language - Can you memorize a bunch of facts really quickly?
It's "nice" if you know some GChem and OChem, you need to actually have mastery over basic arithmetic to do drug calculations (and I mean ratios and proportions math), and it really helps if you have some idea of physiology to more easily understand how and why drugs and pharmacotherapy "can" be rational. But unless you go to a Basic Science heavy school (Rutgers, UConn, old UF, Wisc, Purdue), it is very doubtful that you will be taxed very hard on the basic sciences component or even the applied components of the curriculum.
For OChem, speaking from the faculty's viewpoint, I view someone having lower grades in OChem to be more of an inability to internalize and apply the rules (nomenclature, basic synthesis, mechanisms have rules that at some level, power memorizing won't work) rather than a lack of knowledge. Pharmacy as it is today, that's not a big problem as most go corporate, but I'd rather admit someone who demonstrates better abstract thinking ability as then I don't have to worry about them failing for lack of abstract reasoning alone. That abstract reasoning does come in handy with sympathetic system drugs (which they and their derivatives are basically a half of the major classes you'd need to pick up).
Assuming that you aren't struggling in your other classes, there is no reason why a B- in Ochem should keep you from going to pharmacy school.
I'll give a slight caveat that OChem and GChem are tiebreakers when we have lower SGPA's. A consistently low performance in those scores works against you. I do agree with Biding that it 'shouldn't' keep you from going, but the reality that I see is that they are still used as weed out scores even now though they are not as relevant to future success.
The research work on prerequisites is very equivocal on any one factor with the sole exception of background experience in pharmacy (meaning that you worked as a tech or as a volunteer above 400 hours). Grades, PCAT scores, degree completion, are very weak predictors of academic retention and NAPLEX scores. I know for me, I will excuse and vote for admission from a rather weak (I mean toward the 3.0 GPA and 2.8 SGPA) numbers candidate if they had serious tech or other healthcare worker experience. Not nice but worth saying, if I happen to be acquainted (if not outright know) the pharmacist who wrote the Letter of Recommendation and it is a good one, that's an almost certain admit for me. The network is something that I trust.
