What does the first letter 'A' in the Orange Book signify?

The first letter 'A' in the Orange Book signifies that a drug product is considered therapeutically equivalent to another product. The Orange Book, formally known as the "Approved Drug Products with Therapeutic Equivalence Evaluations," is published by the FDA and provides guidance on the therapeutic equivalence of various drug products. When a drug is labeled with an 'A,' it indicates that it meets the necessary criteria for bioequivalence, meaning that it is expected to have the same clinical effect and safety profile when administered to patients under the conditions specified in the labeling. This classification is crucial for pharmacists and healthcare providers because it ensures that patients can safely substitute one medication for another when necessary, promoting access to affordable medications while maintaining efficacy and safety.