Pharmacology: Routes of Drug Administration

Routes of Drug Administration

• There are different routes by which drugs can be applied or introduced to the body.

Factors Affecting Route of Administration

• The drug itself
• The state of the patient
• Cost of the drug
• Site of action of the drug (local or systemic)

Oral Route

• Drugs are introduced through the mouth in various dosage forms (solutions, emulsions, suspensions, powders, cachets, tablets, and capsules)
• Not suitable for:
  • Emergency situations due to slow onset of action
  • Irritant drugs
  • Unabsorbable drugs (e.g., aminoglycosides)
  • Drugs destroyed by digestive juices (e.g., insulin)
  • Drugs with extensive first-pass metabolism (e.g., lignocaine)
  • Unconscious patients
  • Uncooperative and unreliable patients
  • Patients with severe vomiting and diarrhea

Parenteral Route

• Faster onset of action, making it suitable for emergency situations
• Useful for:
  • Unconscious patients
  • Uncooperative and unreliable patients
  • Patients with vomiting and diarrhea
  • Irritant drugs
  • Drugs with high first-pass metabolism
  • Drugs not absorbed orally
  • Drugs destroyed by digestive juices

Disadvantages of Parenteral Route

• Expensive
• Requires aseptic conditions
• Invasive techniques can be painful
• Cannot be usually self-administered

Importance of Route of Administration

• The quantitative response to a drug depends largely upon its route of administration
• The qualitative response to a drug may also be modified by the route of administration