Which method of medication administration provides the client with the greatest first-pass effect?

The oral method of medication administration is associated with the greatest first-pass effect because it involves the drug being absorbed through the gastrointestinal tract and then transported via the portal vein to the liver. During this process, a significant portion of the drug can be metabolized by the liver before it reaches systemic circulation. This metabolic action can greatly alter the concentration of the drug that ultimately becomes bioavailable to the body.

In contrast, sublingual administration bypasses the gastrointestinal tract and portal circulation, leading to faster absorption and a minimal first-pass effect. Intravenous administration delivers the drug directly into systemic circulation, avoiding the liver entirely at the outset and thus eliminating the first-pass effect. Similarly, subcutaneous administration also allows for the medication to enter systemic circulation without passing through the liver first. Therefore, among these routes, oral administration presents the greatest potential for first-pass metabolism and reduced bioavailability of the drug.