Parenteral medications and nutrition

Medications that are given intravenously bypass the digestive processes. These medications reach the bloodstream almost immediately and can be useful in emergency situations where fluid replacement is needed and another dosage form is not appropriate. A parenteral dosage form may be administered several ways, including methods such as intravenous (IV), intramuscular (IM), intracardiac (IC), and intrathecal (IT).

Intravenous (IV) injection medications are administered directly into the bloodstream through a vein. It is the most common parenteral route, and it has rapid effects. Injections can be via a syringe and needle, or in some cases through a pump or programmable machine, such as for pain or diabetes control. This route is administered either through a peripheral line or a central line. A peripheral line goes into the extremities, such as the arm, hands, and feet.

Peripheral veins are smaller, which allows medication to be injected easier. This is the most common method of administration. A central line is used for a weak patient or one who has weak peripheral veins. Medications, such as total parenteral nutrition (TPN) or chemotherapy, are usually too concentrated for peripheral veins and are given centrally through an implanted port because there is more blood volume running through these larger veins.

Intramuscular (IM) injections, such as hormones, vaccinations, and some antibiotics, are given directly into the muscle. Intracardiac (IC) injection medications are usually used in emergencies and typically found on emergency or crash carts. These medications, such as epinephrine, are often used quickly to resuscitate a patient and therefore are packaged in prefilled disposable syringes with attached needles. The intradermal (ID) route is used to inject medications in the capillary rich layer below the epidermis, such as in a skin test for tuberculosis. The intrathecal (IT) route is used for injections directly into the space surrounding the spinal cord. Meningitis patients often receive injections through the IT route when a spinal tap is performed. All medications given through this route are preservative free because the body may not be able to break them down, which could cause permanent paralysis. Intra-arterial injections may be used to inject anesthesia medications or dyes into an artery during a procedure, such as a heart catheterization. The subcutaneous route of administration is used for slowly absorbed medications like insulin or heparin.

A direct injection, often called a bolus or IV push (IVP), is a small amount of medication in a syringe injected directly into a port in an existing IV line over 5 to 15 minutes, such as a pain medication. Pain or nausea medications for a hospital patient may be injected through the IV line for patients who already have an IV line inserted. This type of injection allows the patient to receive necessary medications without the additional “stick” or puncture.

Epidural injections are given into the epidural space, such as anesthesia medication during labor.

Oral dosage forms must pass through the digestive processes to reach the bloodstream and be distributed to the organs and tissues.

Some drugs, such as heparin (an anticoagulant), are broken down completely by stomach acids and for this reason must be given parenterally. Therefore, much of what determines the best route of administration is due to the drug’s effectiveness. There are also diseases or conditions that lead to the inability of a patient to be able to take an oral dose form, such as a tablet or an oral solution. These may include patients who are:

Intravenous administration

There are different types of IV administration. An IV injection can be a small amount of medication in a syringe injected directly into the vein through the skin, such as a pain medication. This method is called IV push. Sometimes these are injected directly into a port in an existing IV line to avoid an additional puncture in the skin. If a larger amount of medication is need, it may be given as an IV infusion. This is designed to allow the medication to flow into the bloodstream over a longer period of time, such as in a blood transfusion or antibiotic treatment, which takes about 30 minutes.

IV medications may be given continuously or intermittently. This is usually in the form of a large volume parenteral (LVP) between 250 to 1000 mL and over 2 to 24 hours. The orders will determine a rate of infusion, which is the amount of fluid that should enter the body over a certain period of time (Figure 2-1). This is often regulated with an infusion pump or electronic device. Examples of IV injections include hydration fluids, blood products, or drugs that need to be maintained at a constant or steady level for the patient.

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