What is high volume of distribution mean?

A high volume of distribution (Vd) indicates that a drug extensively distributes throughout the body's tissues and compartments, rather than remaining confined to the bloodstream. This suggests that the drug may have a high affinity for tissues or can permeate cell membranes easily. A high Vd often correlates with a longer duration of action and may require higher doses for effective therapeutic levels in the plasma. It can also imply that the drug is less likely to be effectively cleared by the kidneys or liver.