Which form of a molecule is described as being ionized?

The term "ionized" specifically refers to a state of a molecule where it has gained or lost an electron, resulting in a net electrical charge. When a molecule is ionized, it can exist in forms known as cations and anions. A cation is a positively charged ion, while an anion is negatively charged.

In the context of local anesthetics, the ionized form of a molecule is crucial because it influences the drug's ability to penetrate nerve membranes and exert its effects. Typically, the ionized form, which is charged, is less able to cross lipid membranes compared to its unionized counterpart. Therefore, the term "ionized form" encompasses both cations and anions and is precisely what the question refers to.

The term "unionized form" describes a molecule that is neutral and uncharged, which allows for better permeability through cell membranes. The cationic form refers to a positively charged species, and the anionic form refers to a negatively charged species, both of which are subsets of the broader category of ionized forms. Thus, the correct characterization of the ionized state itself is accurately described by the term ionized form.