Routes of Administration

Intravascular administration

[ROUTES OF ADMINISTRATION]

Places a drug directly into the bloodstream, resulting in immediate effect and 100% bioavailability.

Intravascular administration

[ROUTES OF ADMINISTRATION]

This route does not undergo absorption; the drug is directly distributed.

Dissolution

Rate-limiting step prior to absorption

Bioavailability

How much of the drug reaches the systemic circulation.

Extravascular administration

[ROUTES OF ADMINISTRATION]

Involves the drug being delivered to a site outside the bloodstream, requiring an absorption process that leads to delayed and potentially incomplete bioavailability.

Intravascular

[ROUTES OF ADMINISTRATION]

Intravascular vs. Extravascular route

• Direct to bloodstream; 100% bioavailability

Extravascular

[ROUTES OF ADMINISTRATION]

Intravascular vs. Extravascular route

• Requires absorption

• potentially incomplete bioavailability

• Intravenous (IV)

• Intra-arterial

• Intracardiac

Example of Intravascular route [3]

• Parenteral (Extravascular)

• Oral

• Subcutaneous

• Intramuscular

• Intranasal

• Intradermal

• Intrathecal

• Sublingual

• Rectal

• Ocular

• Urethral

• Vaginal

• Transdermal
  

Example of Extravascular route [13]

Intravenous (IV)

[ROUTES OF ADMINISTRATION]

• Immediate onset of action

• 100% bioavailability

• Precise dose control

Intravenous (IV)

[ROUTES OF ADMINISTRATION]

• Risks: Toxicity, infection, embolism

• Cannot be recalled once given

Intravenous (IV)

[ROUTES OF ADMINISTRATION]

Best for: Emergencies

Embolism

Can dislodge a blood clot, causing it to travel through the bloodstream

Pulmonary embolism

[Types of Venous thromboembolism]

Clot travels to lungs

Deep vein thrombosis

[Types of Venous thromboembolism]

Clot forms in deep veins, usually legs

Intra-Arterial (IA)

[ROUTES OF ADMINISTRATION]

Delivers drug directly to target organ

Intra-Arterial (IA)

[ROUTES OF ADMINISTRATION]

Used in chemotherapy and imaging

Intra-Arterial (IA)

[ROUTES OF ADMINISTRATION]

• High risk of tissue necrosis – maximum concentration in the organ

• Rarely used routinely

• Example: Regional cancer chemotherapy

Tissue necrosis

The tissue/organ dies

Intracardiac (IC)

[ROUTES OF ADMINISTRATION]

• Emergency-only route

• Direct injection into the heart

Intracardiac (IC)

[ROUTES OF ADMINISTRATION]

• Very high risk

• Largely replaced by IV route

Intracardiac (IC)

[ROUTES OF ADMINISTRATION]

• Example: Cardiac resuscitation (historical use)

Enteral Route

Extravascular Route is also known as ____ ?

Oral (PO)

[ROUTES OF ADMINISTRATION]

Most common and convenient route

Oral (PO)

[ROUTES OF ADMINISTRATION]

Subject to First-pass effect metabolism (in the liver)

Onset

Refers to “How long before the drug takes effect”

Oral (PO)

[ROUTES OF ADMINISTRATION]

• Variable absorption (affected by food, pH, motility)

• Slower onset compared to parenteral routes

Oral (PO)

[ROUTES OF ADMINISTRATION]

• Not suitable for patients who are vomiting, unconscious, or NPO (Nothing By Mouth)

• Avoid for: Acid-labile drugs, emergencies

Oral (PO)

[ROUTES OF ADMINISTRATION]

Examples: Paracetamol, Amoxicillin

Sublingual (SL)

[ROUTES OF ADMINISTRATION]

• under the tongue; directly connected to superior vena cava

Sublingual (SL)

[ROUTES OF ADMINISTRATION]

• Absorbed directly via the oral mucosa

• Bypasses first-pass metabolism

Sublingual (SL)

[ROUTES OF ADMINISTRATION]

Rapid onset – but may also be excreted quickly

Sublingual (SL)

[ROUTES OF ADMINISTRATION]

Drug must be lipophilic and potent

Sublingual (SL)

[ROUTES OF ADMINISTRATION]

• Patient must not swallow the drug

• Example: Nitroglycerin (NTG)

• Sublingual (SL): 2–3 kg hardness

• Buccal: 8–10 kg hardness → HARDER

Between sublingual (SL) and buccal, which tablet is harder?

Buccal

[ROUTES OF ADMINISTRATION]

• Slower onset than sublingual

• More sustained absorption

Buccal

[ROUTES OF ADMINISTRATION]

• Bypasses first-pass metabolism

• Less irritation than sublingual route

Buccal

[ROUTES OF ADMINISTRATION]

Examples: Buccal testosterone, Fentanyl

Fentanyl

______-

• 300x more potent than morphine

• Opioid analgesic

• Side Effect (SE): Respiratory depression

Rectal

[ROUTES OF ADMINISTRATION]

• Useful if oral route is not possible

• Partially bypasses first-pass metabolism

  • 1/3 (upper part) → Hepatic Portal Vein → Subject to First-Pass (FP) metabolism

  • 2/3 (middle and lower part) → Iliac vein→ No First-Pass (FP) metabolism

Rectal

[ROUTES OF ADMINISTRATION]

• Absorption can be erratic

• Useful in pediatrics and geriatrics

Rectal

[ROUTES OF ADMINISTRATION]

• Example: Diazepam suppository (for Seizure)

seizure

Diazepam suppository is for ____ ?

Rectal suppository

[Type of Suppository Bases]

Made of Theobroma cacao (cocoa butter)

Vaginal suppository

[Type of Suppository Bases]

Made of Polyethylene Glycol (PEG)

Subcutaneous (SC)

[ROUTES OF ADMINISTRATION]

• Slower absorption than IM

• Limited volume (≤ 1–2 mL)

Subcutaneous (SC)

[ROUTES OF ADMINISTRATION]

• Absorption affected by blood flow

• Suitable for self-administration

Subcutaneous (SC)

[ROUTES OF ADMINISTRATION]

• Examples: Insulin, Heparin

• Avoid: Irritant drugs

Subcutaneous (SC)

[ROUTES OF ADMINISTRATION]

Injection sites should be rotated to prevent tissue damage.

Lipodystrophy

An alteration in fat cells due to repeated injections at the same site (common with insulin).

True

[True or False]

• Blood flow affects the rate of absorption.

90° angle

[ROUTES OF ADMINISTRATION]

Intramuscular (IM) is conducted in _____ angle

Intramuscular (IM)

[ROUTES OF ADMINISTRATION]

Faster absorption than subcutaneous (SC)

Intramuscular (IM)

[ROUTES OF ADMINISTRATION]

• Larger volume allowed (2–5 mL)

• Can use depot preparations

Intramuscular (IM)

[ROUTES OF ADMINISTRATION]

• Risk of pain and nerve injury

• Examples: Vaccines, Benzathine penicillin

Depot preparation

A preparation in which the drug is stored and released slowly over time

Sciatic nerve

If the ____ nerve is hit during intramuscular injection, can lead to paralysis.

Intradermal (ID)

[ROUTES OF ADMINISTRATION]

• Very small volume (≤ 0.1 mL)

• Slow absorption

Intradermal (ID)

[ROUTES OF ADMINISTRATION]

Mainly for diagnostic purposes

Intradermal (ID)

[ROUTES OF ADMINISTRATION]

Examples:

• Tuberculin skin test

• Allergy testing

Tuberculin skin test

Used for diagnosing tuberculosis (TB).

Intrathecal (IT)

[ROUTES OF ADMINISTRATION]

• Injected directly into cerebrospinal fluid (CSF)

Intrathecal (IT)

[ROUTES OF ADMINISTRATION]

Bypasses blood–brain barrier

Intrathecal (IT)

[ROUTES OF ADMINISTRATION]

Requires strict aseptic technique

Intrathecal (IT)

[ROUTES OF ADMINISTRATION]

High risk of neurotoxicity

Intrathecal (IT)

[ROUTES OF ADMINISTRATION]

Examples:

• Methotrexate

• Spinal anesthesia

Inhalational

[ROUTES OF ADMINISTRATION]

• Rapid absorption due to large surface area of the lungs

• Avoids first-pass metabolism

Inhalational

[ROUTES OF ADMINISTRATION]

Useful for local and systemic effects

Inhalational

[ROUTES OF ADMINISTRATION]

Technique-dependent (patient must use correctly)

Inhalational

[ROUTES OF ADMINISTRATION]

Examples:

• Salbutamol

• Anesthetic gases

Salbutamol (also known as Albuterol)

_______-

• It is used for acute asthma.

• It is a β₂ agonist (bronchodilator).

Inranasal

[ROUTES OF ADMINISTRATION]

• Rapid onset

• Bypasses first-pass metabolism

Inranasal

[ROUTES OF ADMINISTRATION]

• Limited dose volume

• Possible nasal irritation

Inranasal

[ROUTES OF ADMINISTRATION]

Examples:

• Desmopressin (analogue of vasopressin)

• Naloxone (for opioid poisoning)

Naloxone

Analogue of vasopressin

Naloxone

Used for opoid poisoning

Ocular (Ophthalmic)

[ROUTES OF ADMINISTRATION]

• Mainly local effect

• Minimal systemic absorption

Ocular (Ophthalmic)

[ROUTES OF ADMINISTRATION]

• Requires sterility

• Frequent dosing needed

Ocular (Ophthalmic)

[ROUTES OF ADMINISTRATION]

Examples:

• Timolol

• Aantibiotics (Tobramycin)

Tobradex

Used for sore eyes (eye infections/inflammation).

• Contains:

  • Tobramycin (antibiotic)

  • Dexamethasone (corticosteroid)

Vaginal

[ROUTES OF ADMINISTRATION]

• Local or systemic effect

• Bypasses first-pass metabolism

• Variable absorption

Vaginal

[ROUTES OF ADMINISTRATION]

Useful for hormonal therapy

Vaginal

[ROUTES OF ADMINISTRATION]

Examples:

• Clotrimazole

• Estrogen creams

fungal infection

Clotrimazole is for _____infection.

Urethral

[ROUTES OF ADMINISTRATION]

• Local action

• Rarely used

Urethral

[ROUTES OF ADMINISTRATION]

Limited patient acceptability

Urethral

[ROUTES OF ADMINISTRATION]

Example: Alprostadil (for erectile dysfunction)

Alprostadil

A very small tablet for erectile dysfunction

Transdermal

[ROUTES OF ADMINISTRATION]

Use for both local and systemic

Transdermal

[ROUTES OF ADMINISTRATION]

• Sustained drug release

• Bypasses first-pass metabolism

Transdermal

[ROUTES OF ADMINISTRATION]

Requires potent, lipophilic drugs

Transdermal

[ROUTES OF ADMINISTRATION]

Skin irritation possible

Transdermal

[ROUTES OF ADMINISTRATION]

• Fentanyl

• Nicotine

• NTG patch

• Scopolamine patch

Angina pectoris

NTG (Nitroglycerin) patch is used for _____ ?

Angle for Administration of Injection