The process in which a drug in a higher concentration passes through a permeable membrane to a lower concentration is known as what?

The correct answer to the question is diffusion. This process involves the movement of molecules from an area of higher concentration to an area of lower concentration through a permeable membrane. It is a fundamental concept in pharmacology and biology, as it explains how substances, including drugs, move within the body or in different environments.

In diffusion, the molecules naturally spread out in an attempt to achieve equilibrium, which is when the concentration is uniform across the area. This process does not require energy, making it a passive transport mechanism.

Osmosis, on the other hand, specifically refers to the movement of water across a semi-permeable membrane and involves the concentration of solutes rather than the solutes themselves. Thus, while both diffusion and osmosis involve the movement of substances across membranes, osmosis is exclusive to water movement, making diffusion the more appropriate choice in this context.

Filtration relates to the movement of particles through a membrane under pressure, and exfiltration is a term not commonly used in this physical context, further supporting that diffusion is the relevant process being described.