Which statement correctly distinguishes absorption from distribution?

Which statement correctly distinguishes absorption from distribution?

• A. Absorption Occurs at Site of Action
• B. Distribution to Target Tissue Occurs After Absorption
• C. Absorption Happens After Metabolism
• D. Absorption Does Not Involve the Bloodstream

Answer: (B)

Absorption is the process by which a drug enters the bloodstream from the site of administration, while distribution is the subsequent movement of that drug from the blood into tissues, including the target site. In pharmacokinetics, the typical sequence is absorption first, then distribution (and then metabolism and excretion can follow). Therefore, saying that distribution to the target tissue occurs after absorption correctly reflects the order in which the drug reaches and then leaves the bloodstream to reach tissues. Absorption does not occur at the site of action—the site of action is where the drug exerts its effect, which is often in a different tissue after distribution. Metabolism can occur after absorption, but it is not the defining sequence for distinguishing absorption from distribution. And absorption inherently involves entry into the bloodstream (directly or via first-pass routes); saying it does not involve the bloodstream would be incorrect.

Absorption is the process by which a drug enters the bloodstream from the site of administration, while distribution is the subsequent movement of that drug from the blood into tissues, including the target site. In pharmacokinetics, the typical sequence is absorption first, then distribution (and then metabolism and excretion can follow). Therefore, saying that distribution to the target tissue occurs after absorption correctly reflects the order in which the drug reaches and then leaves the bloodstream to reach tissues.

Absorption does not occur at the site of action—the site of action is where the drug exerts its effect, which is often in a different tissue after distribution. Metabolism can occur after absorption, but it is not the defining sequence for distinguishing absorption from distribution. And absorption inherently involves entry into the bloodstream (directly or via first-pass routes); saying it does not involve the bloodstream would be incorrect.