Non-peroral extra-vascular routes refer to drug administration methods outside the gastrointestinal (GI) tract.
These routes offer various advantages, such as avoiding first-pass metabolism and enabling targeted drug delivery.
The major routes include:
1) Topical/Transdermal
Mechanism: Drugs are applied to the skin and absorbed into systemic circulation.
Examples: Creams, ointments, patches, gels.
Advantages
Non-invasive administration
Prolonged drug release
Avoids first-pass metabolism
Useful for local and systemic effects
Disadvantages
Limited penetration of certain drugs
Potential for skin irritation
Inconsistent absorption
Factors Affecting Absorption
Skin integrity, hydration, thickness
Molecular weight and lipophilicity of the drug
Use of penetration enhancers
2) Inhalation
Mechanism: Drugs enter through the respiratory tract and are absorbed via alveoli.
Examples: Aerosols, powders, gases.
Advantages
Rapid drug onset
High bioavailability
Avoids first-pass metabolism
Targeted delivery for respiratory conditions
Disadvantages
Risk of respiratory irritation
Difficult to control dosage
Requires proper inhalation technique
Factors Affecting Absorption
Lung surface area and blood flow
Drug particle size and solubility
Inhalation device efficiency
3) Rectal
Mechanism: Drugs are absorbed through the rectal mucosa into circulation.
Examples: Suppositories, enemas.
Advantages
Avoids first-pass metabolism
Useful for patients unable to take oral medications
Provides local or systemic effects
Disadvantages
Discomfort and patient reluctance
Inconsistent absorption
Factors Affecting Absorption
Rectal mucosal surface area and blood flow
Drug’s molecular weight and lipophilicity
Formulation (e.g., suppository base)
4) Sublingual/Buccal
Mechanism: Drugs dissolve in the oral mucosa and enter the bloodstream directly.
Examples: Sublingual tablets, buccal patches.
Advantages
Rapid onset of action
Avoids first-pass metabolism
Suitable for patients unable to swallow pills
Disadvantages
May cause local irritation
Limited to specific drugs with appropriate solubility
Factors Affecting Absorption
Oral mucosal surface area and blood flow
Drug’s molecular weight and lipophilicity
Tablet or patch formulation
5) Intramuscular (IM) Injection
Mechanism: Drugs are injected into muscle tissue and absorbed through capillaries.
Examples: Vaccines, analgesics, antibiotics.
Advantages
Rapid and consistent absorption
Suitable for large drug volumes
Effective for long-acting formulations
Disadvantages
Pain and discomfort at the injection site
Risk of tissue damage or infection
Factors Affecting Absorption
Drug solubility and formulation
Injection site (e.g., deltoid, gluteal muscle)
Patient’s age, weight, and health status
6) Subcutaneous (SC) Injection
Mechanism: Drugs are injected beneath the skin and absorbed into circulation.
Examples: Insulin, heparin, biologics.
Advantages
Slow and sustained drug release
Suitable for self-administration
Disadvantages
Pain at the injection site
Risk of tissue irritation and infection
Factors Affecting Absorption
Drug solubility and stability
Injection site (e.g., abdomen, thigh)
Patient-specific factors
7) Intravenous (IV) Injection
Mechanism: Drug is directly injected into a vein, bypassing absorption.
Examples: Antibiotics, chemotherapy, emergency medications.
Advantages
Immediate drug action
100% bioavailability
Suitable for large volumes and precise dosing
Disadvantages:
Requires trained personnel
Risk of infection, vein damage, and adverse reactions
Factors Affecting Administration
Drug solubility and stability
Patient’s vein condition
Infusion rate
8) Pulmonary (Inhalation Therapy)
Mechanism: Drug is inhaled and absorbed through alveolar membranes.
Examples: Bronchodilators, anesthetic gases.
Advantages
Rapid onset of action
Requires lower doses compared to oral administration
Effective for respiratory diseases
Disadvantages
Risk of lung irritation
Limited to drugs that can be aerosolized
Factors Affecting Absorption
Drug particle size and solubility
Inhalation technique and device efficiency
9) Intraocular (Ophthalmic)
Mechanism: Drug is administered directly into the eye for local absorption.
Examples: Eye drops, ointments.
Advantages
Targeted delivery for eye conditions
Reduces systemic side effects
Disadvantages
Risk of eye irritation and infection
Limited systemic absorption
Factors Affecting Absorption
Drug solubility and pH
Tear production and drainage
10) Vaginal
Mechanism: Drug is absorbed through the vaginal mucosa for local or systemic effects.
Examples: Vaginal tablets, creams, rings.
Advantages
Targeted delivery for reproductive health
Avoids first-pass metabolism
Disadvantages
Potential for irritation
Limited systemic absorption
Factors Affecting Absorption
Vaginal mucosal permeability
Drug formulation and solubility
Here is the table with the route, mechanism, and examples of drug absorption from non-peroral extra-vascular routes
Route | Mechanism | Examples |
Topical/Transdermal | Drug diffuses through skin into circulation | Creams, ointments, patches |
Inhalation | Drug absorbed via alveoli in lungs | Aerosols, powders, gases |
Rectal | Drug absorbed through rectal mucosa | Suppositories, enemas |
Sublingual/Buccal | Drug dissolves in oral mucosa and enters bloodstream | Sublingual tablets, buccal patches |
Intramuscular (IM) | Injected into muscle, absorbed via capillaries | Vaccines, antibiotics |
Subcutaneous (SC) | Injected under skin, absorbed into circulation | Insulin, heparin |
Intravenous (IV) | Direct injection into a vein, bypassing absorption | Antibiotics, chemotherapy |
Pulmonary | Drug inhaled, absorbed through alveoli | Bronchodilators, anesthetics |
Intraocular | Drug applied to eye, absorbed locally | Eye drops, ointments |
Vaginal | Drug absorbed through vaginal mucosa | Vaginal tablets, creams |
