Any insur carrier including BCBS has hundreds if not thousands of plans. So it's not a question of what BCBS covers but what the plan you are in covers. State law often requires plans to cover certain things such as pre-existing conditions. So to some extent it's also specific to your state AND your plan. If you can't get an answer from BCBS or your husband's employer, try the state insurance office.
Logically speaking, if this medication prevents something bad from happening, eg your husband's heart medication, they should cover it. If not, they could end up covering husband's hospital stay, rehab, etc. Certainly a LOT more money for them. So I don't see why they wouldn't cover it.