Which statement is true about IM versus SubQ administration?

Which statement is true about IM versus SubQ administration?

• A. IM can accommodate larger volumes than SubQ
• B. IM has slower onset than SubQ
• C. SubQ bypasses first-pass metabolism
• D. SubQ is always faster than IM

Answer: (A)

Absorption and dosing capacity differ between intramuscular and subcutaneous routes because muscle tissue is more vascular and can hold larger fluid volumes than fat tissue. That vascularity and space allow intramuscular injections to deliver higher volumes (often several milliliters, depending on the site and patient), while subcutaneous injections are typically limited to smaller volumes (about 0.5 to 1 mL, sometimes up to 2 mL for certain products). This difference in volume tolerance also partly influences how quickly the drug enters systemic circulation, with intramuscular routes often providing faster onset due to better blood flow, though formulation specifics matter. Both intramuscular and subcutaneous injections bypass first-pass metabolism (it’s the oral route that undergoes hepatic first-pass), so the statement about first-pass is not correct. The claim that subcutaneous injections are always faster than intramuscular ones is also incorrect.

Absorption and dosing capacity differ between intramuscular and subcutaneous routes because muscle tissue is more vascular and can hold larger fluid volumes than fat tissue. That vascularity and space allow intramuscular injections to deliver higher volumes (often several milliliters, depending on the site and patient), while subcutaneous injections are typically limited to smaller volumes (about 0.5 to 1 mL, sometimes up to 2 mL for certain products). This difference in volume tolerance also partly influences how quickly the drug enters systemic circulation, with intramuscular routes often providing faster onset due to better blood flow, though formulation specifics matter. Both intramuscular and subcutaneous injections bypass first-pass metabolism (it’s the oral route that undergoes hepatic first-pass), so the statement about first-pass is not correct. The claim that subcutaneous injections are always faster than intramuscular ones is also incorrect.