Routes of Administration

1. Session 8 : Routes of Drug
Administration
1

2. Learning objectives
By the end of this session students are
expected to be able to:
Define Route of Drug Administration
Explain the Major Routes of Drug
Administration
Explain Advantages and Disadvantages
of Each Route of Drug Administration
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3. Activity: Brainstorming!!??!
What is a route of drug administration?
3

4. Definition of Route of Drug
Administration
A route of drug administration is the path by which
a drug is brought into contact with the human
body
The choice of which route of drug
administration to be used depends on two
factors which are:
i. The existing preparations of the drug
ii. The state of the patient:
When administering a drug, ensure that the
pharmaceutical preparation is appropriate for
the route specified
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5. Activity: Buzzing!?!
What are the major routes of drug
administration?
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6. Major Routes of Drug
Administration
There are four major routes of drug
administration which are commonly used:
1. Enteral route
2. Parental route
3. Topical route
4. Inhalation route
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7. Enteral route
 This is the route which involves part of
gastrointestinal tract
 Drugs are absorbed into the bloodstream
and pass through the liver on the way to
their target organ/tissue
 Enteral route includes Oral route,
Sublingual route, Buccal route and Rectal
route
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8. Parental route
This involves injection via a hollow
needle into the body at various sites and
to varying depth
Parenteral routes includes Intradermal,
Subcutaneous route (S.C),
Intramuscular route (I.M), Intravenous
injections (I.V)
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9. Topical route
Drugs are applied topically to the skin or
mucous membranes, mainly for local
action
Inhalation route
Medication is sprayed or inhaled into
nose, throat, and lungs
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10. Small group discussion
What are the advantages and
disadvantages of the different routes of drug
administration?
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11. Enteral Route
Oral route: The mouth is commonly used route
for administering drugs
Advantage of oral route administration
1. Most convenient to use
2. Safe, does not break the skin barrier
3. The gastrointestinal tract provides a huge
surface area for absorption
4. The drug can be taken at home by a patient
5. Portable
6. No pain, easy to take
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12. Disadvantage of oral route administration
• Absorption can also depend on the stomach
contents.
• Drugs may affect gastric emptying and this
may affect absorption
• Inappropriate for patient with nausea and
vomiting
• Drug may have unpleasant taste and odour
• Inappropriate if patient cannot swallow or is
unconscious
• Drugs may irritate gastric mucosa
• Some of the drugs may be destroyed by the
gastric juices example insulin 12

13. Oral route
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14. Sublingual route
The medication is placed under the
tongue and allowed to dissolve slowly
Because of the rich blood supply in this
region, there is rapid onset of the action
The patient is instructed not to move the
drug with the tongue not to eat or drink
anything until the medication has
completely dissolved
14

15. Advantage of sublingual route
administration
Same as oral route, plus
1. Drug can be administered for the local
effects
2. More potent than oral because the drug
directly enter the circulation and
bypasses the liver metabolism(first
pass effect)
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16. Disadvantage of sublingual route
administration
1. If swallowed drug may be inactivated
by gastric juice
2. Drug must remain under the tongue
until dissolved and absorbed
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17. Sublingual route
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18. Buccal route
The tablet or capsule is placed in the
oral cavity between the gum and the
cheek
The client is instructed not to manipulate
the medication with the tongue;
otherwise, it could get displaced to the
lingual area where it will be more rapidly
absorbed or to the back of the throat
where it could be swallowed
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19. Advantage of buccal route administration
Same as sublingual route
Disadvantage of buccal route administration
The same as sublingual plus
1. Dose absorbed is unpredictable
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20. Buccal route
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21. Rectal Route
This means the drugs passed through
the rectum
Rectal drugs are normally in suppository
form, although a few laxatives and
diagnostic agent are given via enema
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22. Advantage of rectal route
1. Favours the drugs which has offensive taste
or odour, or when it can be changed by
digestive enzymes
2. Drug released at slow steady rate
3. It avoids irritation of the upper
gastrointestinal tract
4. Is convenient and safe method of giving
drugs when the oral method is unsuitable
5. Venous blood from the rectum does not
pass to the liver thus no first pass effect
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23. Disadvantage of rectal route
1. Absorption is slower than other routes
2. Irregular and uncompleted absorption
3. Causes irritation to the rectum
4. Inconvenience to administer
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24. Inhalation route
Inhalation is the breathing of air vapour or
volatile drugs into the lungs
The gaseous drugs are inhaled and
absorbed through epithelium of the alveoli
of the lungs
Drug administered through this route may
be for the local or systemic effects
Examples of the drug are volatile
anaesthetic agents such as ether and
halothane 24

25. Inhalation route
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26. Advantage of inhalation route
1. Acts very quickly because the lungs
have a larger surface area for
absorption and reach blood supply
2. Drugs act at the site of action e.g. in
asthmatic condition
3. Introduces the drug throughout
respiratory tract
4. Can be used to unconscious patients
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27. Disadvantage of inhalation route
1. Poor regulation of dosage
2. Inconvenience in use
3. Drug intended for localized effect can
have systemic effects
4. Limited to respiratory system only
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28. Topical Route
This means application of drug locally at an
intended site such as skin, eye, ear or nose
Used for smoothing and softening the dry and
rough areas of the skin
May also be used to provide antiseptic or
bacteriostatic effects in order to inhibit the
growth and multiplication of micro organism
May also be used to provide a cleansing
effects for the removal of dirt dermis or
infected tissue
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29. Topical route
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30. Advantage of topical applications
1. Provide a local effect
2. Few side effects
Disadvantage of topical route
1. Drug can enter body through abrasions
and cause systemic effects
2. May stain clothes
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31. Parenteral route
The term parenteral is used to indicate the
administration of drugs by “Injections”
The common types of injections includes,
intradermal, subcutaneous, intramuscular
and intravenous
Drugs given parenterally must be sterile,
readily soluble, absorbable, and non-
irritating
Sterile aseptic technique must be used to
avoid infection 31

32. Intradermal route
Injection is made in the upper layer of
the skin to the dermis
The amount of drug given is small and
absorption is slow
Common method used for allergy
testing
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33. Intradermal route
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34. Advantage of intradermal route of
administration
1. Absorption is slow (this is an
advantage in testing for allergies)
Disadvantage of intradermal route
1. Amount of drug administered must be
small
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35. Subcutaneous route
Small amount of drug in solution are given
subcutaneously (hypodermically)
The needle is inserted through the skin
with quick movement, but the injection is
made slowly and steadily
Advantage of subcutaneous route
1. Onset of drug action is faster than oral
route
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36. Subcutaneous route
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37. Disadvantage of subcutaneous route
1. Involve sterile technique
2. More expensive than oral
3. Only small volume of drug can be
administered
4. Some drugs can irritate tissue and
cause pain
37

38. Intramuscular route
Injections are made through the skin and
subcutaneous tissue into the muscular tissue
Muscle tissue has a rich blood supply,
medication moves quickly into blood vessels
to produce more rapid onset of action than the
oral route
The anatomical structure of the muscle
permits this tissue to receive a larger volume
of medication.
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39. Intramuscular route
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40. Advantage of intramuscular injection
1. Pain from irritating drug is minimized
2. Can administer larger volume than
subcutaneous
3. This injection is technically easier than
via I.V route
4. The gastrointestinal tract and first pass
metabolism are avoided
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41. Disadvantage intramuscular injections
1. Break skin barrier
2. Can produce anxiety
3. Injections can be painful
4. Self-administration is difficult
5. Rarely, abscesses can form at the site of
injection
6. The needle may puncture a small blood
vessel and cause bruising of the skin
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42. Intravenous injections
Medications and fluids are administered
directly into the blood stream.
is used when a very rapid onset of
action is desired
It requires skill and sterile asepsis,
I.V route is of great value in
emergencies
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43. Intravenous injections
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44. Advantage of I.V route
1. A rapid onset of action
2. The entire injected dose is almost
instantly available, since it bypasses the
gastrointestinal tract and first pass
metabolism
3. A lower dose is administered than if the
drug is given orally
4. Administration is useful for drugs that are
irritant when administered intramuscularly
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45. Disadvantage of I.V routes
1. Break skin barrier
2. Limited to highly soluble drugs
3. Drug distribution inhibited by poor
circulations
4. The drug has to be administered by
trained person
5. Involuntary injection into an artery can
cause arterial spasm with resulting tissue
damage
6. Accidental overdose can have serious
consequences 45

46. Key points
• A route of drug administration is the path by
which a drug is brought into contact with the
human body
• The choice of which route of drug administration
to be used depends on the existing preparations
of the drug and the state of a patient
• There are four major routes of drug
administration which are commonly used. These
are enteral, inhalation, parenteral and topical
routes
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47. Evaluation
• What is the route of drug administration?
• What are the types of parenteral route?
• Which are factors to consider when
selecting the route of drug administration?
• What are the advantages of Intravenous
route over oral route?
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48. References
• Aulton, M.E., Taylor, M.K. (2001).
Pharmaceutics: The Science of dosage form
design (2nd ed.). USA: Churchill Livingstone
• Cooper, J.W., Gunns, C., & Carter, S.J. (2008).
Dispensing for Pharmaceutical Students (12th
end). Delhi, India: CBS Publishers and
Distributors.
• Rawlins, E.A. (2001).Bentley’s Textbook of
Pharmaceutics (8th ed.). London, UK: Bailliere
Tindall.
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