Which statement correctly describes a pharmacokinetic advantage of intramuscular injection compared to subcutaneous administration?

• A. Bypasses liver first-pass metabolism
• B. Substantially slower onset for all drugs
• C. Requires lipophilic vehicles exclusively
• D. Always limited to small volumes

Answer: (A)

Parenteral routes bypass hepatic first-pass metabolism, so the drug reaches systemic circulation without being subject to the liver’s initial processing. Intramuscular injection shares this feature with subcutaneous administration, so describing it as bypassing liver first-pass metabolism is a true pharmacokinetic property of injectable routes in general. This makes it a valid advantage of IM use over oral dosing, and it’s the best fit among the options because the other statements aren’t universally true: onset with IM is not inherently slower for all drugs, IM does not require lipophilic vehicles exclusively, and IM is not limited to small volumes—it can accommodate larger volumes than subcutaneous administration.