Which letter in the Orange Book denotes an injectable solution made with oils?

In the context of the Orange Book, which is a resource published by the FDA that provides information on the therapeutic equivalence of drug products, the letters assigned to different categories are important for understanding their formulations.

The letter "O" specifically denotes injectable solutions made with oils. This classification is crucial because it informs pharmacists and healthcare providers about the characteristics of the injectable solutions, including their stability and compatibility with other formulations. Recognizing that "O" is assigned to oil-based injectable solutions helps ensure safe and effective medication administration, as oil-based formulations can have different pharmacokinetic properties and potential interactions compared to aqueous or other types of solutions.

The other letters represent different categories of drug formulations. For example, "A" typically indicates products that are considered therapeutically equivalent to their reference counterparts, "B" refers to products that are not therapeutically equivalent, and "P" denotes products that are considered to meet specific criteria but are not classified as oil solutions. Understanding these distinctions is vital for pharmacists to make informed decisions about drug substitutions and patient care.