Which theory describes oriented-wedge?

• A. Plastic/interfacial film theory
• B. Solubilization theory
• C. Micellar theory
• D. Oriented-wedge theory

Answer: (D)

The idea being tested is how molecules arrange themselves at interfaces and how that orientation affects solubility and dissolution. The oriented-wedge theory specifically describes surfactant or amphiphile molecules organizing at a hydrophobic–water interface in a tilted, wedge-like arrangement. This structured, oriented layer around the interface lowers interfacial tension and creates a favorable pathway for solubility and transfer of drug molecules across the interface. This focus on the geometry and directional organization at the interface is what sets oriented-wedge theory apart from the other theories. The plastic/interfacial film theory envisions a solid-like film at the surface that acts as a barrier to dissolution rather than a specific orientation of molecules; the solubilization theory and the micellar theory describe solubilization mechanisms in solution via micelles rather than the interfacial orientation of wedge-shaped molecules.