Milling is primarily utilized to improve bioavailability for which BCS class drugs?

Milling is an essential process in pharmaceutical formulation, particularly for enhancing the bioavailability of drugs. Bioavailability refers to the extent and rate at which the active ingredient or active moiety is absorbed and becomes available at the site of action.

Drugs categorized as Class 2 according to the Biopharmaceutical Classification System (BCS) are poorly soluble but highly permeable. These drugs often face challenges in absorption due to their low solubility, meaning milling can significantly enhance their dissolution rate and, consequently, their bioavailability. Reducing the particle size increases the surface area and can help overcome solubility limitations.

On the other hand, Class 3 drugs are highly soluble but have low permeability, while Class 4 drugs are both poorly soluble and poorly permeable. For Class 3, milling is not typically needed since their high solubility assists in absorption. Class 4 drugs might benefit from milling to a certain degree, but improving their bioavailability is often more complex than just particle size reduction.

Class 1 drugs, which are both highly soluble and highly permeable, do not require milling to improve their bioavailability as they already exhibit optimal absorption characteristics.

Within this framework, the correct choice reflects the understanding that milling is particularly useful for