Which route of administration is absorbed more slowly than IM injections?

Subcutaneous (SQ) administration is absorbed more slowly than intramuscular (IM) injections due to the differences in the vascularity of these tissue types. The subcutaneous tissue has fewer blood vessels compared to the muscles where IM injections are administered. As a result, medications injected subcutaneously are absorbed at a slower rate into the bloodstream because they must pass through the fewer available capillaries in the subcutaneous layer.

In contrast, intramuscular injections are delivered into a well-vascularized area, allowing for rapid absorption into the circulation. This difference in absorption rates is critical for determining the onset and duration of action of medication, especially when quick therapeutic effects are needed.

Other routes mentioned, such as intravenous (IV) and oral (PO), provide different absorption characteristics. IV injections are absorbed immediately since they are directly introduced into the bloodstream, while oral medications undergo extensive absorption processes through the gastrointestinal tract, which can also lead to variable absorption rates influenced by various factors. However, neither IV nor oral routes absorb more slowly than subcutaneous injections.