Drugs with affinity for the vessel-poor group have what effect on volume of distribution?

Drugs with affinity for the vessel-poor group have what effect on volume of distribution?

• A. Higher volume of distribution
• B. Lower volume of distribution
• C. No effect on volume of distribution
• D. Volume of distribution equals total body water

Answer: (A)

Volume of distribution reflects how far a drug spreads from the bloodstream into the body's tissues. When a drug has affinity for the vessel-poor group—tissues with low blood flow such as adipose or certain poorly perfused compartments—it tends to be sequestered in those tissues rather than remaining in plasma. This distribution lowers the plasma concentration for a given amount of drug, so the calculated Vd (Dose divided by plasma concentration) becomes larger. In other words, extensive tissue uptake, especially into poorly perfused tissues, makes the apparent volume of distribution higher. If the drug stayed mostly in plasma or stayed bound to plasma proteins, the Vd would be lower; conversely, distribution into tissues aligns with a higher Vd.

Volume of distribution reflects how far a drug spreads from the bloodstream into the body's tissues. When a drug has affinity for the vessel-poor group—tissues with low blood flow such as adipose or certain poorly perfused compartments—it tends to be sequestered in those tissues rather than remaining in plasma. This distribution lowers the plasma concentration for a given amount of drug, so the calculated Vd (Dose divided by plasma concentration) becomes larger. In other words, extensive tissue uptake, especially into poorly perfused tissues, makes the apparent volume of distribution higher. If the drug stayed mostly in plasma or stayed bound to plasma proteins, the Vd would be lower; conversely, distribution into tissues aligns with a higher Vd.