Which of the following is a characteristic of a closed formulary?

A closed formulary is a specific type of health insurance plan design where only a subset of medications is covered, particularly those that fall within a designated list. The key characteristic that defines a closed formulary is that it restricts coverage to a limited number of medications, and often requires prior authorization for certain drugs.

When it comes to the option indicating that it does not cover formulary drugs without prior authorization, this aligns with the nature of closed formularies. Patients may need to provide justification to their insurer to receive coverage for certain medications, thus restricting access unless those criteria are met.

In contrast, the other options describe features that do not align with a closed formulary. A formulary that covers all medications would be classified as open, not closed. Allowing unlimited access to brand-name drugs suggests a lack of restrictions that contradicts the concept of a closed formulary, which often emphasizes the use of generic alternatives or formulary-specific medications. Additionally, offering a wide range of over-the-counter medications is not a typical characteristic of closed formularies, as these plans are primarily focused on prescription medications and their covered alternatives.