Parenteral Route of Drug Administration

There might be a lot of confusion about what is the parenteral route? Well, any route that is not enteral (external) is called the parenteral route. Drug administration through the parenteral route is performed only by injection. Parenteral drug administration is done using a needle and a syringe or by inserting an indwelling catheter. Parenteral route of administration means drug administration by any non-oral means it specifically means injecting directly into the body, penetrating the skin and mucous membranes. The parenteral route of administration is preferred over other drug administration routes in emergencies such as cardiac arrest and anaphylactic shock (extreme allergic reaction). This type of drug administration has a lot of advantages like first-pass metabolism avoidance, better bioavailability compared to other drug administration routes, and reliable dosage. In the comparison of oral drug administration, parenteral drug administration or parenteral therapy has better control over the dose and rate of the medication, thus it generates better and predictable pharmaco-dynamic and pharmaco-kinetic profiles.

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Advantages of Parenteral Route

• One of the advantages of parenteral route of drug administration is specially chosen for drugs that have poor absorption in the gastrointestinal tract, and other drugs like insulin and heparin which are unstable in the gastrointestinal tract.

• Another reason for using the parenteral route is that it can be used on patients who are unconscious, uncooperative, and vomiting or on patients under circumstances that require rapid onset of action to stabilize them.

• Bioavailability in parenteral drug administration is faster and more predictable.

• Interference for the medication by liver metabolism is avoided in parenteral drug administration.

• There are zero chances of interference in the course of action of the medication by food or digestive enzymes.

• Absorption of the active form of the drug becomes easy, as it is essential in certain cases.

Although there are various advantages of parenteral route, there are a few disadvantages of this route of drug administration. A couple of disadvantages of the parenteral route are stated below:

• Drug administration by the parenteral route is irreversible and is riskier than the other routes of drug administration.

• Parenteral drug administration is an invasive route of drug administration, and thus it can cause pain, tissue damage, and infections.

• A parenteral injection has limitations for the delivery of protein products, specifically the ones that require sustained levels.

• Parenteral drug administration is riskier.

• The injection prepared to be injected always has to be sterile.

• Medical assistance or help is always required while administering any dose through parenteral injection.

Various Parenteral Route Types

A parenteral injection is of different types, each type is required for different forms of medication, and every type has a separate method. A few of the parenteral route examples are intramuscular, subcutaneous, intravenous, and intradermal injections. All the types are explained below:

• Intramuscular injection or IM is the injection of a medicine or drug into the muscles. It is one of the numerous methods used for the parenteral administration of medication into the patient’s body. Intramuscular injection is often preferred over other methods because muscles have numerous blood vessels than the subcutaneous tissue which fastens up the absorption of the drug than subcutaneous or intradermal injections. Medications or drugs that are administered through intramuscular injections are not subject to the first-pass metabolism effect which can affect other oral medications.

• A subcutaneous injection is directly administered into the subcutis. It is the layer directly below the dermis and epidermis. It is collectively referred to as the cutis. Subcutaneous injections are effective in administering medications like insulin and morphine among others. Subcutaneous tissues have very few blood vessels thus the drugs injected here are meant to act slowly at sustained rates of absorption.

• Intravenous injection often abbreviated as IV injection is a traditional medical technique that helps deliver fluids, medications, and nutrition to a person directly into their vein. Intravenous injection is also used to administer medical therapies and other medications like blood products or electrolytes to regulate electrolyte imbalances in the patient’s body. Intravenous therapy was recorded as early as the 14th century but failed to become widespread until the 19th century till the techniques were developed for safe and effective medical use.

• Intradermal injections, often abbreviated as ID, are shallow or superficial injections of any medication into the dermis, between the epidermis and the hypodermis. ID injections are complex and are not the preferred route of administration for injection. They are only used for certain therapies like tuberculosis tests and allergy tests.

Enteral Vs Parenteral Route

Enteral drug administration delivers the medication or the substance into the body through the gastrointestinal tract. In enteral drug administration both ends of the GI tract are utilized, the mouth and the anus. It is one the most common routes of drug administration.

Parenteral drug administration is preferred for therapies of serious infections. In parenteral drug administration, high therapeutic concentrations are achieved. It is reliable and rapid. This method is tried and tested and is reliable.

Conclusion

With the parenteral route, an immediate physiological response is achieved, which is vital in a condition such as cardiac arrest. Parenteral therapy is needed for drugs that are not effective in enteral routes. Parenteral therapy stabilizes disturbances of fluid and electronic balance in the body. If food or other medications cannot be taken by mouth they can be supplied by the parenteral route.