Routes of administration

2. Route of administration
•Is the path by which a drug, fluid,
poison, or other substance is taken
into the body.
•Routes of administration are generally
classified by the location at which the
substance is applied.
•Routes can also be classified based
on where the target of action is.

3. •
ROA
ENTERAL
ORAL
SUBLINGUAL
RECTAL
PARENTERAL
S/C
I/M
I/V
OTHERS
OTHERS
TOPICAL
INHALATION

4. SELECTION OF ROUTES
• Must be correlate with the site of drug
action.
• Drug nature/characteristics of the drug.
• Duration of action.
• Effect of gastric pH, digestive enzymes.
• First-pass metabolism
• Patient status.
• Desire of the patient.

5. Enteral routes
(Through the intestines)
•In this route the drug is placed in the
Gastrointestinal Tract and then it
absorbs to the blood.
i. ORAL OR PER OS (P.O.)
Oral route is the most common
route of administration. It is safe,
convenient, cheap and does not
require the services of a skilled
personnel.

6. Advantages
• Safer.
• Cheaper.
• Painless.
• Convenient for
repeated and
prolonged use.
• Can be self-
administered.
Disadvantages
• Not suitable for emergency.
• It is not suitable for/in:
 Unpalatable and highly
irritant drugs.
Unabsorbed drugs (e.g.
aminoglycosides).
Drugs that are 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 diarrhoea.

7. Buccal and Sublingual (SL)
• Some drugs are taken as smaller tablets which are held in
the mouth or under the tongue.
• Buccal tablets are often harder tablets designed to
dissolve slowly.
• This ROA is also used for some steroids.
• E.g. nitroglycerine, Nicotine containing chewing gum,
testosterone and oxytocin

8. • ADVANTAGES
• Quick onset of action.
• Action can be
terminated by spitting
out the tablet.
• Bypasses first-pass
metabolism.
• Self-administration is
possible.
• Drug stability
• DISADVANTAGES
• Holding the dose in the
mouth is inconvenient.
• It is not suitable for:
Irritant and lipid-
insoluble drugs.
Drugs with bad smell
and taste.
• Unpleasant taste of
some drugs

9. Factors to be considered
1. Lipophilicity of drug.
2. Salivary secretion.
3. pH of the saliva.
4. Binding to oral mucosa.
5. Thickness of oral
epithelium.

10. Rectal administration
• Drugs given by the rectal route a most commonly given as
suppository or enema.
• Because the rectum's wall is thin and its blood supply rich,
the drug is readily absorbed.
• 1. Suppository: It can be used for local (topical) effect as
well as systemic effect, e.g. indomethacin for rheumatoid
arthritis.
• 2. Enema: Retention enema can be used for local effect
as well as systemic effect.
• The drug is absorbed through rectal mucous membrane
and produces systemic effect, e.g. diazepam for status
epilepticus in children.

11. Advantages
• Unconscious patients and
children
• If patient is having
nauseous or vomiting.
• By-pass liver - Some (but
not all) there may be a
reduced first-pass effect.
Disadvantages
• Erratic absorption.
• Absorption may be
variable.
• May cause irritation.
• The patient may be
embarrassed.

12. Parenteral routes
• In this route of administration the drug does not pass
through the gastrointestinal tract. It directly reaches to the
blood.
• It can further be classified into two classes:-
• 1. With injections e.g. Intravascular, Intramuscular,
Subcutaneous
• 2. Without injections: - e.g. Inhalations.

13. Advantages
i) Drug is neither invaded
nor destroyed by
digestive enzymes.
ii) A higher concentration
of drug in blood is
achieved.
iii) Absorption is complete
and predictable.
iv) In emergency this
method is particularly
useful.
Disadvantages
1. It is expensive.
2. Asepsis must be
maintained to avoid
infection.
3. Pain may accompany
or follow the injection.
4. It requires the services
of a professionally
skilled personnel.

14. • Onset of action often occurring in
15–30 seconds for IV, 10–20
minutes for IM and 15–30
minutes for SC
• They also have essentially 100%
bioavailability and can be used
for drugs that are poorly
absorbed or ineffective when they
are given orally.
• Some medications, such as
certain
• antipsychotics, can be
administered as long-acting
intramuscular injections.
• On-going IV infusions can be
used to deliver continuous
medication or fluids.

15. Intra Dermal
S/C I/M
I/V

16. INHALATION
• Inhalation
• May be used for a local effect, e.g. bronchodilators.
• Can be used for systemic effect, e.g. general anaesthesia.
• Rapid absorption by-passing the liver.
• Absorption of gases is relatively efficient, however solids
and liquids are excluded if larger than 20 micron and even
then only 10 % of the dose may be absorbed.
• Cromolyn is taken as a powder with 50 % of the particles
within the range of 2 to 6 micron. Larger than 20 micron
and the particles impact in the mouth and throat.
• Smaller than 0.5 micron and they aren't retained. Some
portion of the dose may be swallowed.

17. TOPICAL ROUTE
1. Skin
2. Mucous Membranes