Drug Administration Routes Overview

Drug Administration Routes

• Drugs are administered via various routes, affecting absorption, distribution, metabolism, and excretion (ADME).
• Routes influence drug effect onset, intensity, and duration.
• Route selection depends on drug properties (e.g., solubility, stability), patient condition, and desired therapeutic effect.

Oral Administration

• Drugs are taken orally, absorbed through the gastrointestinal tract.
• Advantages: ease, convenience, low cost.
• Disadvantages: variable absorption, first-pass metabolism, delayed onset.
• Factors affecting oral absorption include gastric emptying, intestinal motility, and drug-food interactions.

Intravenous Administration

• Drugs are injected directly into a vein.
• Advantages: rapid onset, precise control, suitable for large volumes.
• Disadvantages: risk of adverse effects (thrombosis, infections), extravasation risk.
• Requires trained personnel.

Intramuscular Administration

• Drugs are injected into muscle tissue.
• Advantages: slower, more prolonged absorption than IV, suitable for depot medications.
• Disadvantages: potential pain, discomfort, absorption variability depending on blood flow.

Subcutaneous Administration

• Drugs are injected beneath the skin.
• Advantages: slow, controlled absorption, suitable for prolonged or depot effects.
• Disadvantages: potential irritation, variable absorption.
• Commonly used for insulin delivery.

Topical Administration

• Drugs applied to skin or mucous membranes.
• Advantages: localized action, reduced systemic effects.
• Disadvantages: potential skin irritation, variable absorption.
• Used for treating localized infections, inflammation, skin conditions.

Inhalation Administration

• Drugs inhaled as gases or aerosols, reaching lungs rapidly.
• Advantages: rapid delivery to lungs, localized respiratory effects.
• Disadvantages: potential irritation, variability in deposition, specialized devices needed.
• Commonly used for bronchodilators, inhaled corticosteroids.

Rectal Administration

• Drugs administered rectally.
• Advantages: bypasses first-pass effect, suitable for unconscious or vomiting patients.
• Disadvantages: variable absorption, potential rectal irritation.
• Used for medications needing systemic effects.

Factors Affecting Drug Absorption

• Drug solubility (lipid and water solubility).
• Drug formulation (e.g., tablet, capsule, solution).
• Patient factors (age, health, diet).
• Site of administration.
• Blood flow to the absorption site.

Drug Distribution

• Absorbed drugs are distributed throughout the body.
• Distribution relies on blood flow, capillary permeability, and drug binding to plasma proteins.
• Drugs can concentrate in specific tissues/organs based on affinity.

Drug Metabolism

• Drugs undergo biotransformation in the liver and other organs.
• Metabolism aims to reduce drug concentration or change form for excretion.
• Metabolution can alter drug activity, causing side effects.

Drug Excretion

• Drugs and metabolites are eliminated from the body.
• Kidneys are the main excretion route; others include liver (bile), lungs, sweat glands.
• Excretion rate influences drug duration and intensity.

Dosage Considerations

• Correct dosage is vital for desired effect, minimizing adverse effects.
• Patient weight, age, organ function influence dosage determination.
• Dosage forms (e.g., tablets, capsules, liquids) affect absorption rate/extent.

Drug Administration Errors

• Proper techniques, precautions crucial for correct administration.
• Errors in route, dose, or timing cause adverse effects (toxicity, treatment failure).
• Monitoring drug levels and patient responses is critical.