Statuses can differ between therapeutic categories. For instance, a drug can be preferred in one category and approved in another category. You will need to check with your health plan to ensure they will reimburse you for a drug not on their formulary. In general, if the drug has a status of 'approved' or 'preferred', it will be reimbursed. If the drug has a status of 'non-formulary' or 'prior authorization', it may be reimbursed as usual, at a different rate or not at all.
Doctors can prescribe any medication they choose.
However, if the drug is not listed on the formulary and you cannot obtain it through the plan's prior authorization process, you may have to pay the total cost of the medication.