Routes of Drug Administration

Question 1

To administer a drug is to…

Answer 1

…make the drug accessible to the patient’s body where the effect is desired.

Question 2

Conditions for drug administration to be effective

Answer 2

The drug must come in contact with the tissues of organs and cells of tissues by one way or the other

Question 3

How is a drug able to come in contact with the tissues and cells where it is needed?

Answer 3

By the route of administration of drug.

Question 4

A route of administration in pharmacology…

Answer 4

The path by which a drug and other substances are taken into the body

Question 5

What influences the choice of route of administration?

Answer 5

1. Physioclinical nature of drug or dosage forms
2. Nature of drug - polar or non-polar
3. Desired bioavailability (how much will get into systemic circulation in a period of time)
4. Desired onset of action
5. Nature and location of disease
6. Desired duration of action
7. Clinical condition or patient

Question 6

Examples of drug dosage forms

Answer 6

Solid
Aerosol
Solution
Suspension
Ointment/Lotion
Volatile liquid

Question 7

Classification of route of drug administration

Answer 7

This is based on the site of application - systemic and local

Question 8

The routes of drug administration for systemic effect may be divided into…

Answer 8

2 major groups:

Oral (enteral)
Parenteral (systemic)

Question 9

Enteral drug administration

Answer 9

It has to do with the GI tract and includes oral, buccal, and rectal.

Question 10

Parenteral drug administration means…

Answer 10

…not through the alimentary canal or mouth. Here, drugs are administered without crossing the intestinal mucosa.

Question 11

Interrectal administration

Answer 11

Through rectum

Question 12

Sublingual administration

Answer 12

Under the tongue

Question 13

Examples of enteral administration

Answer 13

• Interrectal
• Sublingual
• Through intragastric tube

Question 14

Advantages of oral route

Answer 14

• Safe
• No sterility required
• Minimal danger of acute drug reaction
• Convenient
• Variety of dosage forms available

Question 15

Disadvantages of oral route

Answer 15

1-Ingestion could cause gastric irritation.
2-Nausea
3-Vomiting
4-Complexes formed with ingested drug could prevent the drug absorption
5-Drug destruction due to low pH
6-Hepatic first pass effect

Question 16

How does the hepatic first pass effect affect oral administration?

Answer 16

Drugs absorbed orally are transported to the general circulation via the liver. Thus drugs which are extensively metabolized will be metabolized in the liver during absorption.

Question 17

The most important and most frequently used parenteral routes are:

Answer 17

I.V. (intravenous route),
IM (intramuscular route)
SC (subcutaneous route)

Question 18

Less frequent parenteral routes

Answer 18

Tissue infiltration
Intra articular
Intradermal
Epidural (around dura matter of spinal cord)
Subarachnoid (between brain’s arachnoid membrane)
Intra-arterial
Intrathecal (within spinal theca)

Question 19

Advantages of parenteral route of drug administration

Answer 19

• Faster, predictable bioavailability.
• No gastric irritation and vomiting
• Can be used in unconscious, uncooperative and vomiting patients
• Interference of digestive enzymes eliminated
• Liver enzymes by-passed

Question 20

Disadvantages of parenteral routes

Answer 20

• More risky
• Sterile preparation required

- Intensive and painful

Question 21

Which route can by-pass hepatic first effect?

Answer 21

Drug administered by all routes except intra-arterial might still be eliminated by first pass elimination in liver prior to distribution to the rest of the body.

Question 22

Examples of local route of administration

Answer 22

Topical (skin)
Intranasal/Inhalational drops
Ocular drops
Transdermal medication

Question 23

What is local administration?

Answer 23

The local route is the simplest mode of administration of a drug at the site where the desired action is required.