Compared to IM, subQ injections have slower and more constant absorption.

• A. False
• B. Sometimes faster
• C. True
• D. Depends on drug formulation

Answer: (D)

Absorption rate depends on both the route and the drug’s formulation. Muscle tissue has higher blood flow than subcutaneous tissue, so many drugs reach the bloodstream faster when given intramuscularly. But this isn’t universal. Subcutaneous injections can be absorbed slowly and steadily if the formulation is designed as a depot or extended-release, while some drugs given subcutaneously as solutions may be absorbed quickly. Likewise, certain formulations intended for IM administration can have slower or more variable absorption depending on particle size, suspensions, or tissue factors.

So whether subcutaneous absorption is slower and more constant than intramuscular absorption isn’t fixed for all drugs; it depends on how the drug is formulated. This is why the best answer is that absorption characteristics depend on the drug formulation.