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Understanding the Different Routes of Medication Administration

In 2020, it was estimated that around $1.3 trillion was spent on prescription medication around the world. In 2011, 8.3% of the annual budget of the NHS was spent on prescriptions – and there were over 1 billion of them dispensed by GPs alone. By 2020, this had risen to £9.61 billion and 1.11 billion prescription items. However, there are lots of different types of medication and routes for its administration. From oral ingestion to intravenous infusion, healthcare professionals have an important decision to make to ensure the best outcomes for patients and their medical conditions. In this article, we explore the different routes of medication administration to create a comprehensive guide.

Importance of Selecting the Appropriate Route

Choosing the appropriate route of medication administration is essential for ensuring the effectiveness and safety of pharmacotherapy. The route of medication administration impacts several aspects:

  • Its absorption
  • Its distribution
  • How it is metabolised
  • How it is excreted
  • Its ultimate therapeutic outcomes.

Various factors, including the chemical properties of the medication, patient-specific considerations and the desired clinical effects, need to be weighed up to determine the most suitable method of administration.

Firstly, the nature of the medication is important when selecting the route. Some drugs are created specifically for oral ingestion. Others, however, need parenteral routes like intravenous or intramuscular injection. This is because they are unable to withstand gastrointestinal degradation or because they need a quicker onset.

This all requires an understanding of pharmacokinetic and pharmacodynamic properties.

Pharmacokinetic properties

Pharmacokinetics refers to how a drug moves through the body. It involves the processes of absorption, distribution, metabolism and excretion (ADME). Understanding this is crucial in determining the concentration of the drug at its site of action. It also helps with the understanding of its potential interactions with other drugs and knowing how long its effects will last. 

Understanding pharmacokinetics means you can optimise dosage regimens and predict any adverse effects. Ultimately, this aids the safe and effective use of the medication. 

Pharmacodynamic properties

This relates to the effects the drug has on the body. While pharmacokinetics is all about how the body affects the drug, pharmacodynamics is all about how the drug affects the body. This includes its mechanism of action, its efficacy, its potency, and the onset and duration of the action. It also encompasses its therapeutic and toxic effects. 

Understanding these properties means you can predict the benefits of the drug on the patient and deal with any side effects that are likely. 

Patient individuality and preference

To understand administration routes of medication, it’s also important to consider individual patient needs and preferences. For example, their age, swallowing ability, gastrointestinal function and other medications taken can impact the feasibility of certain medication administration routes. For instance, paediatric patients or the elderly may have difficulty swallowing pills. Additionally, patients who have liver or kidney problems may require adjustments to their dosage or avoidance of certain routes to prevent toxicity or other adverse effects.

Women taking a tablet

Common Routes of Medication Administration

There are a range of medication administration routes through which drugs can be delivered into the body to achieve therapeutic effects. When all routes are understood, healthcare professionals can select the most appropriate method for their patients and the medication they need. Here are the most common routes of medication administration:

  • Oral administration: This means giving medication by mouth through tablets, capsules, liquids or powders. These medications are absorbed through the gastrointestinal tract. These are often absorbed more slowly compared to other routes and, depending on the medication, may be subject to degradation or altered absorption in the stomach.
  • Intravenous (IV) administration: This means giving medication directly into a vein. It means the onset of action is rapid and precise. It is a common route for emergency situations and in critical care settings. IV administration ensures 100% bioavailability of the drug because it bypasses gastrointestinal absorption barriers.
  • Topical administration: This involves applying medications directly onto the skin or mucous membranes. It includes creams, ointments, gels, lotions and transdermal patches.
  • Injection routes: This involves delivering medications through a needle and syringe. The injections can be intramuscular (IM), which are inserted into a muscle. This allows for slow and sustained absorption. Examples include vaccines, antibiotics and hormonal injections. They can also be subcutaneous (SC), which are inserted into the fatty tissue just beneath the skin. This provides it faster than oral administration and is often used for insulin and medication for autoimmune diseases.

Let’s look at each of these in more detail.

Intravenous (IV) administration

Intravenous (IV) administration is a method of delivering medications directly into the bloodstream through a vein. This route offers several advantages. These include:

  • Rapid onset of action
  • Precise control over drug dosage
  • The ability to administer large volumes of fluid or medication.

However, IV administration also requires meticulous attention to detail and adherence to sterile techniques to ensure patient safety and therapeutic efficacy.

One of the challenges of IV administration is the preparation and administration of the medications. Healthcare professionals must accurately calculate drug dosages and dilute medications as necessary. They must also ensure the drugs are compatible with IV fluids or other medications. Errors in dosage calculations or preparation can have serious consequences for the patient. This includes overdose or adverse drug reactions.

Maintaining sterility throughout the IV administration process is also important. This is in order to prevent infections and complications. Healthcare providers must adhere to strict techniques when handling IV catheters and tubing, for example. This includes thorough handwashing, wearing sterile gloves and using sterile equipment and supplies.

The IV catheter must also be selected and placed with precision. Healthcare professionals must carefully assess the patient’s veins to determine the most appropriate site for catheter insertion. They need to consider factors like vein size, integrity and accessibility.

Improper catheter placement can lead to complications like:

  • Infiltration: This occurs when the IV fluid or medication leaks into the surrounding tissue instead of entering the bloodstream. This happens when the catheter punctures through the vein wall or if it is dislodged. Signs of infiltration include swelling, coolness or pallor around the site. If it is severe, it can lead to tissue damage, impaired circulation and necrosis.
  • Phlebitis: This means that the vein is inflamed. It is often triggered by trauma or irritation. Symptoms include redness, warmth, tenderness and swelling along the vein. It might also feel uncomfortable. Phlebitis can occur for a range of reasons, including catheter movement, chemical irritation from medications or infection. If left untreated, it can progress to more severe complications like thrombophlebitis, where blood clots form in the vein. This poses a risk of embolism or deep vein thrombosis (DVT).

During the IV administration process

While the patient is having IV medication, they must be monitored and assessed throughout. Healthcare professionals must assess for signs of complications such as redness, swelling or pain at the IV site. They also need to check the patient’s vital signs like heart rate, blood pressure and respiratory rate. This is especially true when the patient is having treatment or medications that may affect cardiovascular or respiratory function.

Oral administration

Arguably the most common and convenient route for delivering medication is orally. This means taking the medication through the mouth for it to be absorbed through the gastrointestinal tract and enter the bloodstream.

There are a range of different oral formulations to accommodate different medications and patient preferences. Here are some of the most common oral administration methods:

Tablets

Tablets are a solid form of medication. They contain one or more medications compressed into a small disc shape. These can be scored down the middle to facilitate dose splitting and swallowing. Tablets can be designed to release the medication straight away (called immediate-release tablets) or gradually (called extended or sustained-release tablets).

Liquid medication

This is formula where the active drug is dissolved or suspended in a liquid. These medications are often preferred for young patients or the elderly who have difficulty swallowing solid medication. They come in a range of types. These include syrups, solutions, suspensions and emulsions.

Capsules

These are gelatine or polymer shells that contain powdered or liquid medication. There are two main types: hard capsules, which are typically filled with granules or powders, and soft capsules which contain liquid.

Capsules are good because they mask the taste or smell of medications. They’re also easier to swallow for some people.

Considerations with oral medication administration

When it comes to oral medication, patient compliance is an important consideration. This refers to how well patients adhere to their prescribed medication regimen. Several factors influence this:

  • Dosage form: Patients might prefer a certain dosage based on how easy it is to swallow – or its taste. Healthcare providers should consider patient preferences to improve compliance.
  • Dosage schedule: This is the frequency and timing of medication dosing which can also have an impact on patient compliance. A simple dosing schedule that allows patients to align their medication with their daily routine can help.
  • Instructions and education: Providing clear instructions on how to take medications, including the dosage, timing and other considerations (e.g., taking with food or on an empty stomach) can enhance compliance.
  • Monitoring: Regular follow-up appointments, medication reminders and monitoring can help patients stick to their medication schedule.

Topical administration

Topical administration involves applying medication directly onto the skin or mucous membranes for either local or systemic effects. This offers several advantages. These include the targeted delivery to specific areas, reduced systemic side effects and the convenience of application. These come in various forms:

Creams

These are semi-solid emulsions consisting of a water phase and an oil phase along with emulsifying agents and other additives. Creams are easy to apply. They spread easily over the skin, which makes them suitable for conditions like psoriasis, fungal infections and eczema. Creams provide hydration and occlusive properties. They help to soothe and moisturise the skin while delivering active ingredients.

Ointments

These are semi-solid preparations that consist of a base like petrolatum or lanolin. They have a greasy texture and provide a protective barrier over the skin. They allow for enhanced absorption of medications. These are often used in the treatment of dry or irritated skin conditions. They also deliver medications that require prolonged contact with the skin like antimicrobial agents or corticosteroids. 

Transdermal patches

These are adhesive patches that contain a reservoir of medication. This is gradually released through the skin and into the bloodstream. The patches offer controlled and sustained drug delivery over an extended period of time. This ranges from hours to days. Transdermal patches are often used for delivering medication like hormone replacement therapy (HRT), nicotine replacement therapy and pain management. They are convenient and non-invasive and avoid the need for frequent dosing. They also minimise fluctuations in drug concentration.

Different-Types-of-medication

Injection routes: intramuscular (IM) and subcutaneous (SC)

Injection routes offer effective means of delivering medications directly to the body’s tissues for rapid absorption and systemic distribution. Whether it’s intramuscular (IM) or subcutaneous (SC), each route has distinct characteristics and applications. 

Intramuscular (IM) injection 

Intramuscular injections involve administering medications directly into the muscle tissue. This route offers several advantages. These include rapid absorption and the ability to deliver larger volumes of medication compared to subcutaneous (SC) injections. 

IM injections are commonly used for medications that require rapid onset of action, prolonged duration or effect. They are also given if the medication might irritate subcutaneous tissue. 

IM injections are often used to:

  • Administer vaccines against influenza, tetanus and hepatitis.
  • Deliver antibiotics or treat bacterial infections.
  • Administer hormonal medications like testosterone or progesterone.
  • Pain management like anti-inflammatory drugs or analgesics.

Subcutaneous (SC) injection

These involve delivering medications into the fatty tissue layer under the skin. This offers slower absorption compared to intramuscular injections. It is good for medications that require sustained release or a prolonged duration of action. Subcutaneous injections are commonly used by patients self-administering medications. These injections are less painful too as the area has fewer nerve endings.

SCs are often used for:

  • Insulin to manage diabetes mellitus (Type 1).
  • Anticoagulant medications like heparin. For example, medications after a caesarean section.
  • Vaccines like measles, mumps and rubella.
  • Epinephrine – in emergencies with anaphylaxis, epinephrine is often administered in an EpiPen to allow for rapid absorption when treating severe allergic reactions.
  • Injections of hormones during in vitro fertilisation (IVF) treatment.
  • Certain pain management medications (certain opioids or non-steroidal anti-inflammatory drugs (NSAIDs)).

Both types of injections require proper techniques. This minimises complications and ensures optimal delivery of the medication. Healthcare providers are tasked with selecting the appropriate needle length based on the patient’s anatomy and injection site. Proper injection site preparation and technique are also crucial for the prevention of infection and complications.

Special Considerations and Patient Preferences

When considering any medication, it’s important to take into account patient preferences as well as all of the other factors that may impact the patient’s ability to adhere to their treatment plan. 

Here are some key considerations:

Patient preference

Some patients may have a strong preference for oral medications while others may prefer injections or topical formulations. Understanding their preference can enhance treatment adherence and patient satisfaction. 

Ability to swallow

Patients who have difficulty swallowing such as the elderly, young children, or those with medical conditions like dysphagia may struggle with oral medication. In these cases, alternative routes of administration such as injections or liquid formulations may be more appropriate.

Gastrointestinal absorption

Certain medications have poor bioavailability. They could be susceptible to degradation in the gastrointestinal tract, for example. In these cases, intravenous or subcutaneous injections may be the preferred method. This means the medication can bypass the gastrointestinal system and achieve therapeutic concentrations more reliably.

Dosage form

The formulation of medication can influence the route selection. For example, patients who struggle to apply topical creams might prefer transdermal patches due to their ease of use. Those who require precise dosing or rapid onset of action, however, will benefit from intravenous administration.

Injection phobia

Many patients fear needles, which means they might be less willing to comply with treatment. In some cases, alternative routes of administration should be explored to minimise patient discomfort. 

Doctor giving an injection to a patient

Conclusion 

To summarise, understanding the different routes of medication administration is important for optimal patient care and treatment outcomes. From oral treatments to intravenous infusion, each route has advantages and considerations. To select the appropriate route requires an assessment of the medication’s pharmacokinetic and pharmacodynamic properties as well as patient preferences and needs. 

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About the author

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Louise Woffindin

Louise is a writer and translator from Sheffield. Before turning to writing, she worked as a secondary school language teacher. Outside of work, she is a keen runner and also enjoys reading and walking her dog Chaos.



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