Which statement about oleaginous bases is true?

• A. Water-soluble drugs release well from oleaginous bases.
• B. Lipid-soluble drugs release best from oleaginous bases.
• C. Drug release is independent of solubility.
• D. Oleaginous bases cannot dissolve any drug.

Answer: (A)

Drug release from oleaginous bases depends on how well the drug dissolves in the oil phase. Oleaginous bases are hydrophobic and dissolve lipophilic (lipid-soluble) drugs readily, allowing them to diffuse out into the skin more easily. Water-soluble drugs, on the other hand, do not dissolve well in these bases, so their release is poor. This is why the statement that lipid-soluble drugs release best from oleaginous bases is true. The other propositions fail because they ignore the solubility relationship: water-soluble drugs do not release well from oil bases; release is not independent of solubility; and oleaginous bases can dissolve drugs that are lipophilic.