How are most medications primarily transported throughout the body?

Most medications are primarily transported throughout the body bound to plasma proteins. This binding occurs mainly with proteins such as albumin. When drugs are bound to plasma proteins, they exist in a form that is not pharmacologically active, as only the unbound, or "free," drug can diffuse across cell membranes and exert an effect. The binding to plasma proteins facilitates the transportation of drugs in the bloodstream and helps regulate their availability and distribution in tissues.

This mechanism also serves to prolong the drug's half-life and modulate its effects by controlling the drug's release into the bloodstream. Binding can be influenced by various factors, including the drug’s chemical structure and the concentration of plasma proteins, which can affect the overall therapeutic effectiveness of the medication.

Other methods of transport, such as free drugs in circulation, lymphatic vessels, and cellular transport mechanisms, play roles in specific contexts but are not the primary method of transportation for most medications in standard pharmacological contexts. Thus, the notion that medications predominantly rely on plasma protein binding highlights an essential aspect of pharmacokinetics that influences dosing, efficacy, and safety assessments in clinical practice.