Lääkejakautuminen

Lääkejakautuminen refers to the process by which a drug distributes throughout the body's various tissues and fluids after administration. Once a drug enters the bloodstream, it can move to different parts of the body, such as organs, fat tissue, and even across the blood-brain barrier. This distribution is influenced by several factors, including blood flow to different tissues, the drug's ability to cross cell membranes, its binding to plasma proteins and tissue components, and the physicochemical properties of the drug itself, such as its lipid solubility and ionization state.

The extent to which a drug distributes into different compartments of the body is often quantified by the volume of distribution (Vd). Vd is not a literal physical volume but rather a theoretical volume that represents the amount of fluid required to contain the total amount of drug in the body at the same concentration as in the plasma. A high Vd suggests that the drug distributes widely into tissues outside the bloodstream, while a low Vd indicates that the drug remains primarily within the plasma.

Understanding lääkejakautuminen is crucial for determining appropriate drug dosages and predicting therapeutic effects and potential toxicity. For example, drugs with a high Vd may require higher loading doses to achieve therapeutic concentrations in the plasma and target tissues. Conversely, drugs that are highly bound to plasma proteins will have a smaller fraction of free, active drug available to distribute and exert their effects. Factors like age, disease states, and concurrent medications can also significantly alter drug distribution patterns.