Lipophilicity: Lipophilic substances tend to permeate cell membranes more easily due to their affinity for lipid bilayers. Molecular Size: Smaller molecules generally have higher permeability, whereas larger molecules may require active transport mechanisms. Charge: Ionized substances often have reduced permeability compared to their neutral counterparts. pH and pKa: The permeability of weak acids and bases can depend on the pH of the environment and their dissociation constant (pKa).
