Absorption of drug from Non per-oral extra-vascular routes

Absorption of drug from non per-oral extra-vascular routes covers intramuscular, subcutaneous, inhalation, and transdermal pathways.

Absorption of drug from Non per-oral extra-vascular routes

• 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
     • Suitable for large volumes and precise dosing
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   • 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
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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
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   • 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
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   • Disadvantages:

     • Risk of eye irritation and infection
     • Limited systemic absorption

   • Factors Affecting Absorption:

     • Drug solubility and pH
     • Tear production and drainage
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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
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Here is the table with the route, mechanism, and examples of drug absorption from non-peroral extra-vascular routes

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