parenterally

Parenterally refers to the administration of substances by routes other than the gastrointestinal tract, thereby bypassing digestion and absorption in the gut. The term derives from the Greek para, meaning beside or beyond, and enteron, meaning intestine.

Common parenteral routes include intravenous (IV), intramuscular (IM), subcutaneous (SC or SQ), and intradermal injections. Other non-oral routes used in medicine include intrathecal and epidural injections, regional nerve blocks, and intraosseous access. IV administration is usually the fastest option and may involve peripheral veins or central venous access for large volumes or irritating solutions.

Parenteral administration is used for drugs that are poorly absorbed from the gut, are unstable in the gastrointestinal environment, require rapid onset, or when patients cannot take medications by mouth. It is also used for parenteral nutrition, where nutrients are supplied intravenously (total parenteral nutrition, TPN).

Safety and handling require aseptic technique, sterile preparations, and proper compatibility of solutions and medications. Potential risks include infection, phlebitis, infiltration or extravasation, air embolism, and febrile reactions. Long-term use may require specialized devices such as central venous catheters, and monitoring for metabolic or electrolyte disturbances is necessary with nutrition support.