Routes of Drug Administration Flashcards
To administer a drug is to…
…make the drug accessible to the patient’s body where the effect is desired.
Conditions for drug administration to be effective
The drug must come in contact with the tissues of organs and cells of tissues by one way or the other
How is a drug able to come in contact with the tissues and cells where it is needed?
By the route of administration of drug.
A route of administration in pharmacology…
The path by which a drug and other substances are taken into the body
What influences the choice of route of administration?
- Physioclinical nature of drug or dosage forms
- Nature of drug - polar or non-polar
- Desired bioavailability (how much will get into systemic circulation in a period of time)
- Desired onset of action
- Nature and location of disease
- Desired duration of action
- Clinical condition or patient
Examples of drug dosage forms
Solid Aerosol Solution Suspension Ointment/Lotion Volatile liquid
Classification of route of drug administration
This is based on the site of application - systemic and local
The routes of drug administration for systemic effect may be divided into…
2 major groups:
Oral (enteral)
Parenteral (systemic)
Enteral drug administration
It has to do with the GI tract and includes oral, buccal, and rectal.
Parenteral drug administration means…
…not through the alimentary canal or mouth. Here, drugs are administered without crossing the intestinal mucosa.
Interrectal administration
Through rectum
Sublingual administration
Under the tongue
Examples of enteral administration
- Interrectal
- Sublingual
- Through intragastric tube
Advantages of oral route
- Safe
- No sterility required
- Minimal danger of acute drug reaction
- Convenient
- Variety of dosage forms available
Disadvantages of oral route
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
How does the hepatic first pass effect affect oral administration?
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.
The most important and most frequently used parenteral routes are:
I.V. (intravenous route),
IM (intramuscular route)
SC (subcutaneous route)
Less frequent parenteral routes
Tissue infiltration
Intra articular
Intradermal
Epidural (around dura matter of spinal cord)
Subarachnoid (between brain’s arachnoid membrane)
Intra-arterial
Intrathecal (within spinal theca)
Advantages of parenteral route of drug administration
- 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
Disadvantages of parenteral routes
- More risky
- Sterile preparation required
- Intensive and painful
Which route can by-pass hepatic first effect?
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.
Examples of local route of administration
Topical (skin)
Intranasal/Inhalational drops
Ocular drops
Transdermal medication
What is local administration?
The local route is the simplest mode of administration of a drug at the site where the desired action is required.
