Bio-Transport 56: The Oie-Tozer Equation for the Apparent Distribution Volume скачать в хорошем качестве

Bio-Transport 56: The Oie-Tozer Equation for the Apparent Distribution Volume

In pharmacokinetics, the apparent volume of distribution is a critical parameter for understanding how a drug disperses throughout the body. However, this volume is not a straightforward measurement of physical space. Instead, it is a derived quantity influenced by the physiological and biochemical interactions of the drug, particularly its binding to plasma and tissue proteins. The true complexity of this distribution becomes evident when considering protein binding, which can drastically skew the apparent volume compared to the actual anatomical distribution. To explore this complexity, Oie and Tozer, in their seminal 1979 study, proposed a conceptual framework and corresponding equation that models how protein binding affects drug distribution across body compartments. In their model, the body is partitioned into three major compartments relevant to drug distribution: the plasma compartment (P), the extracellular fluid compartment outside of plasma (E), and the remainder of the body (R). The last compartment includes intracellular spaces where the drug may bind to cell-surface receptors or be internalized through various transport processes. The key assumption is that unbound drug—the pharmacologically active form—is able to freely equilibrate between these compartments.