Routes of Drug Administration

Question 1

What are the different routes of administration?

Answer 1

-Oral
-Sublingual/Buccal
-Rectal
-Intravenous
-Subcutaneous
- Intramuscular
-Inhalation
-Skin

Question 2

Describe oral route

Answer 2

-The drug is administered orally through the mouth then it undergoes dissolution in the stomach followed by absorption in the stomach then liver
-From the liver the drug is distributed to the tissue via portal vein before it exert its therapeutic effect

Question 3

Describe the sublingual/buccal route

Answer 3

-Sublingual (under the tongue), Buccal (between cheek and gum) the blood vein in the oral mucosa directly drain into the systemic circulation bypassing drug metabolism in the liver and intestines.
- This route provides rapid absorption and is suitable for administration in emergency condition but also for lipid-soluble drugs.

Question 4

Describe the rectal route

Answer 4

-Rectal administration is convenient in the following cases: persistent vomiting, difficulty swallowing or in the case of irritant
-It can be used for both systemic and local administration

Question 5

What is systemic drug administration

Answer 5

It is when the drug is carried from the site of administration to site of action (potentially exposing all body to the drug)

Question 6

What is site specific /local administration

Answer 6

It is when the administration route is also the site of the drug action (reduces systemic side effects)

Question 7

Describe intravenous route

Answer 7

-Administration of the drug directly into the systemic circulation and the bioavailability is 100%
-This route is suitable in case of emergency and it is also only suitable for aqueous solution where the patient is monitored

Question 8

Describe the subcutaneous route

Answer 8

-The drug is deposited in the subcutaneous layer it has poor blood vessel so absorption is slow
-Self administration is easy but this route is not suitable for irritant.

Question 9

Describe the intramuscular route

Answer 9

-Direct injection of the drug into the fibres of larger muscles
-Can be used for irritant drug and for the administration of larger quantity of the drug
-Drug absorption depends on the size of the muscle, blood vessel and the nature of the drug administered

Question 10

Describe the inhalation route

Answer 10

-Can be used for both local and systemic actions this is where volatile liquid and gases are administered via inhalation
-Large surface area of the alveoli region provide excellent absorption and rapid onset action

Question 11

Describe the skin route

Answer 11

-Can be used for both local and systemic action
-Skin layers are barrier for drug absorption
-Mostly suitable for lipid soluble drugs

Question 12

What are factors that affect the routes of drug administration?

Answer 12

• Drug liberation
• Drug absorption
• Drug distribution
  -Drug elimination

Question 13

What are the factors that determine the choice of route of administration?

Answer 13

-Patient compliance (easy of administration, palatable,
Age-group)
-Patient condition (conscious, persistent vomiting)
-Site of action (local vs systemic
-Onset of Action (consider enteral and parenteral routes)
-Duration of action (consider LADME)
-Drug quantity (consider IV infusion, or bolus vs Oral)
-Drug metabolism (consider systemic circulation, bioavailability)