extravascularly

Extravascularly means located or occurring outside the blood vessels. In medical writing, it describes processes that involve movement, delivery, or localization in tissues outside the vasculature, as opposed to intravascular or intravenous contexts.

From Latin extra- "outside" + vasculum "vessel," with the suffix -ary forming extravascular, and the adverbial form extravascularly is created in English by adding -ly.

Extravascular administration refers to drug delivery by routes other than injection into a vein or artery, such as oral, subcutaneous, intramuscular, or rectal routes. Drugs absorbed from extravascular sites must cross capillary walls to reach systemic circulation; thus, bioavailability can be incomplete and variable, with typically slower onset than intravenous administration.

In clinical practice, extravascular events describe drugs or fluids that leak into surrounding tissue during IV therapy, a phenomenon known as extravasation. This can cause inflammation, pain, swelling, and potential tissue necrosis, requiring prompt management and sometimes local treatment or antidotes.

Extravascular spaces include the interstitial space and the lymphatic system, where fluids and solutes exchange with the blood plasma. The term is used to describe localization of substances or cells outside the vasculature, such as particles or reagents detected in tissue samples.

See also: intravascular, intravenous, extravasation, routes of administration.