The administration of parenteral medication means delivering medication to outside of the gastrointestinal tract (GI)1. Parenteral drug administration is effective when other routes, such as oral and enteral routes, are difficult to use (i.e. unconscious or unresponsive patients, poor oral bioavailability, and the need for rapid relief of symptoms). The common routes used to deliver parenteral medications is intravenous (IV), intramuscular (IM), subcutaneous (SC), transdermal, topical and inhalation. This section addresses aspects of IV administration that are important to the pharmacist, including parenteral drug administration, IV drug compatibility and drug stability. IV injection can be administered directly into the vein (bolus) or injected into an access port on the IV line.
An IV line is a venous catheter that is inserted into a vein allowing infusion of medication and fluids to a patient (see figure 1 on the right)1. There's a variety of IV access types where the IV line can be placed, but this section will discuss the two most common IV access types, peripheral and central lines.
Venous Peripheral Catheter. Image reference: Creative Commons By 3.0. File:Intravenous therapy 2007- SEP-13-Singapore.JPG
A peripheral line is placed in a smaller vein, most commonly in the hand or arm. It can be inserted in the superficial vein of the feet for pediatrics or neonates. Peripheral lines are simple to insert, but they can only be good for short-term use (≤ 72 hours).
The catheter tip of the central line is placed in a larger vein, usually at the junction of the superior vena cava and right atrium, where the subclavian, jugular or femoral veins are located. With access to the large vein, central lines allow larger volumes of fluid to be infused and higher infusion rates to occur. Central lines are good for administrating irritating medication (i.e. chemotherapy, vasopressors, high concentrations of potassium chloride), and higher osmolality solutions (i.e. total parenteral nutrition). Central line catheters may stay in place for days to weeks. There are various types of lines within the central line. One of the commonly used central line types is peripherally inserted central catheters (PICC) lines. A catheter in this case is inserted peripherally into a vein in the upper arm and is threaded to the central vasculature. Because the tip of the catheter in a PICC line rests at the superior vena cava, and empties the fluid into the right atrium, it can be used for infusing home total parenteral nutrition (TPN), long-term antibiotics, and vesicant solutions (i.e. chemotherapeutic agents, vasopressors, quinupristin/dalfopristin, foscarnet, nafcillin, etc.). A PICC line is preferably used for infusing vasopressors that can cause severe damage to the surrounding tissue.