Routes of Drug Administration – Types, Sites, and Angles

Medication administration is one of the most crucial responsibilities in healthcare practice. For drugs to work effectively, they must reach the site of action in the right concentration and at the right time. This depends largely on the route of administration — the path through which a drug enters the body.

Each route has its own advantages, disadvantages, and specific techniques. Understanding these is vital for all nursing, pharmacy, and medical learners to ensure safe, accurate, and effective medication delivery.

Definition of Route of Administration

The route of administration refers to the path by which a drug, fluid, or other substance is brought into contact with the body for absorption and distribution. The choice of route depends on factors like drug properties, required speed of action, patient condition, and convenience.

Major Categories of Drug Administration

Broadly, medication can be given through two main categories:

1. Enteral Routes – through the gastrointestinal tract (e.g., oral, sublingual, buccal)

2. Parenteral Routes – bypassing the digestive system (e.g., injections, topical, ocular, etc.)

Let’s explore each in detail.

Enteral Routes

a) Oral Route (PO – “Per Os”)

Meaning: The drug is swallowed and absorbed through the digestive system.

Common Forms: Tablets, capsules, syrups, and solutions.

Advantages: Simple, safe, convenient, and cost-effective.

Disadvantages: Slower onset; not suitable for unconscious or vomiting patients.

Example: Paracetamol tablet, Ibuprofen capsule.

b) Sublingual Route

Meaning: Medication is placed under the tongue for quick absorption through oral mucosa.

Advantage: Rapid onset; avoids liver first-pass metabolism.

Example: Nitroglycerin tablets for angina.

c) Buccal Route

Meaning: Medication is placed between the cheek and gum.

Advantage: Rapid absorption, bypasses the liver.

Example: Buccal midazolam for seizures.

Topical Routes

a) Skin (Topical)

Meaning: Drug is applied directly to the skin surface.

Forms: Creams, ointments, gels.

Use: Local effect (antifungal, anti-inflammatory).

Example: Hydrocortisone cream.

b) Transdermal Route

Meaning: A medicated patch that allows the drug to be absorbed slowly through the skin into systemic circulation.

Example: Nicotine patch, Fentanyl patch.

Ophthalmic Route (Eye)

Meaning: Medications applied to the eyes as drops, ointments, or irrigations.

Purpose: Treat eye infections, glaucoma, or inflammation.

Example: Timolol eye drops for glaucoma.

Otic Route (Ear)

Meaning: Drug administered into the ear canal in liquid form.

Use: Treat ear infections, wax buildup, or inflammation.

Example: Ciprofloxacin ear drops.

Parenteral Medication Administration

“Parenteral” means the drug bypasses the digestive tract and is delivered directly into tissues or the bloodstream using injections. It ensures rapid absorption, precise dosing, and quick therapeutic effect.

There are four primary parenteral routes, each defined by its site, angle, and purpose.

a) Intramuscular (IM) Injection

Definition: Medication is injected deep into a muscle for absorption through blood vessels.

Angle: 90°

Common Sites:

• Deltoid (upper arm)
• Ventrogluteal (buttocks)
• Vastus lateralis (thighs)

Advantages: Faster absorption than subcutaneous; suitable for oily or irritating drugs.

Example: Vitamin B12 injection, Vaccines.

b) Intravenous (IV) Injection

Definition: Medication delivered directly into the bloodstream through a vein.

Angle: 25°

Sites:

• Radial vein
• Cephalic vein
• Basilic vein
• Median cubital vein

Advantages: Immediate effect, precise control, suitable for emergency drugs.

Example: IV antibiotics, fluids, chemotherapy.

c) Subcutaneous (SQ or SC) Injection

Definition: Medication injected into the fatty layer beneath the skin but above the muscle.

Angle: 45°

Common Sites:

• Abdomen
• Back of the arm

Advantages: Slow, sustained absorption.

Example: Insulin, Heparin.

d) Intradermal (ID) Injection

Definition: Medication injected just under the epidermis into the dermis layer of the skin.

Angle: 10–15°

Sites:

• Forearm
• Upper back

Advantages: Used for sensitivity testing.

Example: Tuberculin test (Mantoux), Allergy tests.

Table: Comparison of Parenteral Routes

Route	Angle	Common Sites	Absorption Speed	Example
Intramuscular (IM)	90°	Arm, Buttock, Thigh	Moderate to Fast	Vaccine
Intravenous (IV)	25°	Veins of arm	Immediate	Saline, Antibiotics
Subcutaneous (SQ)	45°	Abdomen, Upper arm	Slow	Insulin
Intradermal (ID)	10–15°	Forearm, Upper back	Very Slow	Tuberculin test

Rights of Medication Administration

Medication safety is the foundation of nursing practice. The Six Rights of Medication Administration ensure that every patient receives the correct medicine, dose, and care.

1. Right Patient – Verify the patient’s identity before giving any drug.

2. Right Drug – Check that the medication matches the prescription.

3. Right Dose – Confirm dosage calculations before administration.

4. Right Route – Ensure the drug is administered through the correct route.

5. Right Time – Administer at the prescribed interval.

6. Right Documentation – Record the medication details immediately after administration.

A helpful mnemonic for remembering these is:
“Patients Do Drugs Round The Day.”

Right	Purpose
Right Patient	Prevents giving drug to the wrong person
Right Drug	Ensures medication accuracy
Right Dose	Avoids under or overdose
Right Route	Ensures correct absorption
Right Time	Maintains therapeutic effect
Right Documentation	Provides legal and professional proof

Factors Affecting Route Selection

Patient’s Age and Condition: Infants, elderly, and unconscious patients may need specific routes.

Drug Nature: Some drugs are destroyed by stomach acid and need parenteral administration.

Desired Speed of Action: Emergencies require IV; chronic therapy may use oral or transdermal routes.

Safety and Convenience: Oral is safest and easiest, whereas injections require sterile techniques.

Importance of Aseptic Technique

When administering medications via parenteral routes, aseptic (sterile) technique must be followed to prevent infections.
Always:

• Wash hands before and after.
• Use sterile syringes and needles.
• Clean the injection site with antiseptic.
• Dispose of sharps safely.

All Routes of Administration

Route Type	Example Form	Site of Action	Onset	Remarks
Oral	Tablet, Syrup	GI Tract	Slow	Convenient, safe
Sublingual	Tablet	Oral mucosa	Rapid	Avoids liver metabolism
Buccal	Film	Oral mucosa	Rapid	Useful for emergencies
Topical	Cream	Skin	Variable	Local effect
Transdermal	Patch	Skin	Slow, steady	Sustained delivery
Ophthalmic	Drops	Eyes	Local	Treats eye disorders
Otic	Drops	Ear canal	Local	Ear infections
IM	Injection	Muscle	Fast	Moderate duration
IV	Injection	Vein	Immediate	Rapid effect
SQ	Injection	Fat tissue	Slow	Long-lasting
ID	Injection	Skin dermis	Very slow	Diagnostic testing

Safety and Patient Education

Before administering any medication:

• Explain the purpose and possible side effects to the patient.
• Observe for allergic reactions.
• Encourage patients to report any discomfort.
• Never reuse needles or share medications.

Educating patients about why a certain route is chosen improves compliance and safety.

Clinical Relevance

Understanding the routes of administration helps:

• Choose the most appropriate route for each patient.
• Minimize drug errors and complications.
• Improve therapeutic outcomes.

For example, a nurse giving insulin subcutaneously or a doctor prescribing sublingual nitroglycerin must understand how absorption differs by route.

The route of administration plays a key role in the success of therapy. From oral tablets to complex intravenous infusions, every route demands precision, safety, and understanding.

For healthcare learners, mastering these routes is not just about memorizing angles and sites — it’s about ensuring patient well-being through accurate, ethical, and evidence-based medication practices.

FAQs

Q1. What is the most common route of drug administration?

A: The oral route is most common because it is safe, simple, and economical.

Q2. Which injection has the fastest effect?

A: Intravenous (IV) injection gives an immediate effect since it directly enters the bloodstream.

Q3. Why are different injection angles used?

A: Angles ensure the drug reaches the correct tissue layer — IM (muscle), SQ (fat), ID (skin).

Q4. What is the difference between topical and transdermal routes?

A: Topical acts locally on the skin, while transdermal delivers drugs systemically through skin absorption.

Q5. What are the “Six Rights” in medication administration?

A: Right patient, drug, dose, route, time, and documentation.

Q6. Why is aseptic technique crucial in parenteral routes?

A: To prevent infections, abscesses, and sepsis due to contamination.