Orally administered drugs that are ________ are more rapidly absorbed.

• A. Ionized
• B. Nonionized
• C. Water-Soluble
• D. Lipid-Soluble

Answer: (D)

Oral absorption relies on a drug’s ability to cross the lipid membranes of the intestinal wall. Lipid-soluble (lipophilic) drugs readily dissolve in the cell membrane’s fatty core and diffuse quickly into the bloodstream, leading to faster absorption. In contrast, water-soluble drugs have to move through aqueous pathways or rely on transport mechanisms, which typically results in slower uptake. Ionized (charged) forms are even less able to cross membranes, while nonionized forms can cross more easily, but the general rule is that lipid-soluble compounds are absorbed more rapidly due to their ease of traversing the lipid barrier.