Routes of Drug Administration Overview

Study Notes

Drug Administration Routes

Routes are classified into enteral, parenteral, and other methods based on drug properties and therapeutic goals.

Enteral Routes

Simplest and most common drug administration method.

Oral Administration

Most frequently used method.
Advantages:
- Self-administration is easy.
- No sterilization required, reducing healthcare assistance needs.
- Overdose can often be treated with antidotes.
- Cost-effective compared to parenteral options.
Disadvantages:
- Inconsistent drug absorption.
- Drugs can be degraded in the harsh GI environment (e.g., first-pass metabolism affecting drugs like Propranolol).
- Possible nausea and vomiting.
- Not suitable in emergency situations.
- Can irritate stomach mucosa and have unpleasant taste.

Dosage Forms

Solid forms: Tablets, capsules, powders, and granules.
Liquid forms: Syrups, suspensions, and solutions.

Sublingual Route

Drug placed under the tongue for direct absorption into the systemic circulation.

Parenteral Routes

Involves drug delivery directly into the systemic circulation, bypassing GI tract absorption.
Advantages:
- Rapid absorption and onset of action.
- Convenient for patients needing immediate effects.
- Lower risk of infections with correct technique.
- Avoids GI toxicity and first-pass metabolism.
Disadvantages:
- Can taste unpleasant.
- Not suitable for long-term administration (e.g., nitroglycerin).

Types of Parenteral Routes

Intravenous (IV):
- Most common parenteral method; direct vein injection.
- Advantages:
  - Immediate and accurate drug action.
  - High control over drug levels.
  - Suitable for large-volume infusions.
- Disadvantages:
  - Risk of toxicity with rapid administration.
  - Limited to solutions.
  - Potential for local thrombosis and infections at the catheter site.
Subcutaneous (SC):
- Drug placed under the skin.
- Advantages:
  - Slow absorption rate; can be modified.
- Disadvantages:
  - Limited volume capacity.
  - Risk of lipoatrophy from repeated injections.
Intramuscular (IM):
- Drug injected into muscle mass.
- Advantages:
  - Faster absorption than SC; rate can be modified.
- Disadvantages:
  - Risk of infection or nerve injury.
  - Potential pain at injection site.

Injection Angles

Intramuscular: 90°
Subcutaneous: 45°
Intravenous: 25°
Intradermal: 10-15°

Other Routes of Administration

Inhalation:
- Quick delivery via respiratory tract; ideal for gaseous or aerosolized drugs (e.g., albuterol).
- Minimizes systemic side effects for respiratory conditions (e.g., asthma, COPD).
Intrathecal:
- Direct injection into cerebrospinal fluid; useful for conditions like cryptococcal meningitis.
Intracardiac:
- Direct injection into cardiac muscle, as in cardiac arrest scenarios (e.g., adrenaline).
Topical:
- Localized effect; e.g., clotrimazole for skin infections or tropicamide for pupil dilation.
Rectal:
- Beneficial in bypassing GI degradation; useful when oral intake is problematic.
- Advantages:
  - Protects drugs from digestive enzymes and low pH.
  - Useful for vomiting patients or unconscious individuals.
- Disadvantages:
  - Can cause discomfort and irritation of rectal mucosa.

Description

Explore the various routes of drug administration including enteral, parenteral, and more. This quiz covers the advantages of oral administration and the factors affecting drug absorption. Test your knowledge on how these routes influence therapeutic outcomes.