Which type of formulary allows only listed drugs, except in cases of medical necessity with preauthorization?

A closed formulary is a type of formulary that includes a specific list of covered medications, and typically requires preauthorization for drugs not included on that list, except in cases where there is a documented medical necessity. This means that patients and prescribers may have to go through a process to justify the use of a non-formulary drug based on individual health needs.

This approach helps control costs and encourages the use of medications that are deemed safe and effective while managing the budget for pharmacy benefit plans. In contrast, open formularies include a wide range of drugs, allowing more freedom for prescribers but potentially leading to higher costs. Exclusionary formularies focus on excluding certain high-cost medications while providing coverage for others without as much restriction. Comprehensive formularies aim to cover a wide range of drugs without specific limitations.

In summary, the closed formulary is characterized by its restrictions on drug selection, requiring justification for exceptions, thereby ensuring careful management of pharmaceutical expenditures within a defined scope of medications.