What are the four most common parenteral routes of administration?

The four most common parenteral routes of administration are subcutaneous (SQ), intramuscular (IM), intravenous (IV), and intradermal (ID). These routes are considered "parenteral" because they involve administering medication directly into the body, bypassing the digestive system, which allows for quicker absorption and onset of action compared to oral routes.

Subcutaneous administration involves injecting medication into the fatty tissue just beneath the skin, which is suitable for certain vaccines and medications that require slow, sustained absorption. Intramuscular administration allows for a larger volume of medication to be delivered deep into muscle tissue, ideal for vaccines, hormones, and medications that need to be absorbed more rapidly than subcutaneous injections. Intravenous administration delivers medications directly into the bloodstream, resulting in an immediate effect, which is crucial for emergency situations or when precise dosing is needed. Intradermal administration is primarily used for allergy testing and vaccinations, as it allows for the assessment of the body’s immune response.

The other options contain routes that are not as commonly used in parenteral therapy. For instance, per os (PO) indicates oral administration, which is not considered parenteral. Other routes, like subcutaneous (SC) and intraperitoneal