Which serves as the conduit delivering drug from the site of administration to tissues?

• A. Lymph
• B. Blood
• C. Bile
• D. Urine

Answer: (B)

Drugs reach tissues from the administration site primarily through the circulatory system. After absorption, the drug enters capillaries and becomes part of the blood plasma, which carries it to various tissues. Exiting the blood to enter cells depends on factors like blood flow to the tissue, capillary permeability, and the drug’s ability to cross membranes. The lymphatic system does play a role for certain drugs (especially large or lipid‑soluble ones) but it isn’t the main conduit for delivering drugs to tissues. Bile and urine are mainly involved in elimination (biliary excretion and renal excretion), not distribution to tissues. So the bloodstream is the conduit that delivers the drug from the administration site to tissues.