Intravenous
From Memory Alpha, the free Star Trek reference.
Intravenous (Latin for "within a vein") refers to delivering medicine, fluids or nutrients into the body's blood via a vein. Veins are commonly used for delivery of fluids and nutrients over time because venous pressure does not vary as much as arterial pressure, permitting more consistent, accurate delivery. Medications that are most effectively delivered over time are commonly administered intravenously, also, either by hypospray or by intravenous unit.
Intravenous injection is impossible for Andorians because of their unusual physiology; instead a doctor has to opt for intramuscular injection. (TOS: "Whom Gods Destroy")
