Formulary (pharmacy)

A formulary is a list of prescription drugs covered by a particular drug benefit plan.

Formularies are based on evaluations of efficacy, safety, and cost-effectiveness of drugs. Patients pay varying co-pays for drugs that are on formulary. For drugs that are not on formulary, patients must pay a larger percentage of the cost of the drug, sometimes 100%. Formularies vary between drug plans and differ in the breadth of drugs covered and costs of co-pay and premiums. Most formularies cover at least one drug in each drug class, and encourage generic substitution. Also known as a preferred drug list.