This powerpoint mainly used for the better understanding of different routes of drug administration and its several advantage and disadvantages.

1. Routes of
Administration of
DRUGS
By
Harshit Jadav

2. ROUTES OF DRUG ADMINISTRATION
• Often there is a great choice in selecting the
route by which a drug should be given to
patients.
• condition of the patient and knowledge of
advantages and disadvantages of various
routes are of prime importance in making the
selection of best suiting route.

3. Following are the different ways by which
a therapeutic agent could be given to
patients.
1 Enteral
2 Parenteral
3 Inhalation
4 Topical or Local

4. 1. ENTERAL
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.

5. Disadvantages
•Some drugs are unpalatable and cause irritation of the
intestinal tract resulting in nausea, vomiting and
diarrhea, in particular if these are given before meal.
•Some drugs are destroyed by intestinal enzymes e.g.
insulin is destroyed by intestinal enzymes.
•In case of emergency, when quick action of a drug is
desired this route is not suitable.
•This route is not suitable in the cases of unconscious
patients.
•There is a necessity for cooperation on the part of
patient.

6. f) A very important factor is that blood from
intestinal tract passes via portal vein to the liver
where the drug may be metabolized to a great
extent before being distributed to the site of
action. Thus oral route is not recommended for
drug undergoing extensive FIRST PASS EFFECT.

7. FIRST PASS EFFECT
First Pass Effect may be defined as the loss of
drug as it passes through the gastrointestinal
membranes and the liver, for the first time,
during the absorption process after oral
administration. This is also known Pre-
Systemic elimination.

8. ii SUBLINGUAL
• The tablet is placed under the tongue and
absorption form oral mucosa is rapid and
uniform.
• This route has special importance for certain
drugs.
• For example nitroglycerine is effective when
given sublingually but ineffective when
administered orally.
• The reason is that the drug has very high lipid
solubility.

9. • The major advantage of this route is that
venous drainage from mouth (bucal cavity) is
poured into the superior vena cava and the
drug is saved from first-pass effect.
• It nitroglycerine is given by oral route, the
hepatic first-pass effect is sufficient to
preclude the appearance of any intact
nitroglycerine in the systemic circulation.

10. iii) RECTAL ADMINISTRATION
• The drug may be given rectally for systemic
effect when the patient is either
unconscious or vomiting.
• However, absorption from rectum is
irregular and incomplete and may cause
irritation of rectal mucosa
• Also 50% of the drug absorbed from rectum
passes through liver before entering the
systemic circulation thus first-pass effect
cannot be fully avoided.

11. • The drugs administered reactally are in the
form of suppositories e.g. Ergotamine for the
treatment of migraine.
• Another form of preparation for rectal
administration is the ENEMA i.e. a solution or
suspension of the drug in water or some other
vehicle.
• Suppositories may also be given for local
treatment of rectal conditions e.g. benzocain
is used to relieve pain and itching caused by
haemorrhoids

12. Disadvantages of Rectal Administration:-
a) The patient may be embarrassed.
b) Inflammation of rectum may occur due to
repeated administration.
c) The absorption is irregular specially when
rectum is not empty.

13. 2 PARENTERAL
(Par-beyond enteral-intestine)
• The term parenteral administration implies
the routes through which the drug directly
reaches the body fluids
• By passing the preliminary process of
transport through the intestinal wall or
pulmonary alveoli which is an essential
process when drugs are taken orally, inhaled
or administered reactally.

14. a) Subcutaneous (S/C)
b) Intramuscular (I/M)
c) Intravenous (I/V)
d) Intraperitoneal (I/P)
e) Intradermal
f) Intra Medullary
g) Intrathecal
h) Intraarticular
i) Intra-cardiac
j) Intra arterial

15. Advantages
• Drug is neither invaded nor destroyed by
digestive enzymes.
• A higher concentration of drug in blood may
be achieved because the hepatic
metabolism of drug due to First-Pass effect
is avoided.
• Absorption is complete and predictable.
• In emergency this method is particularly
useful. If the patient is unconscious,
uncooperative or vomiting, the Parenteral
therapy becomes necessary.

16. Disadvantages
• It is expensive because all the parenteral
preparations should be sterilized.
• Asepsis must be maintained to avoid
infection.
• An intravascular injection may accidentally
occur when it is not actually intended.
• Pain may accompany or follow the injection.
• It requires the services of a professionally
skilled personnel because it is difficult for
the patient to perform the injection himself.

17. a) Subcutaneous:-
• The drug is dissolved in a small volume of
vehicle and injected beneath the skin from
where the absorption is slow and uniform.
• Substances causing irritation to the tissues
should not be injected otherwise they will
cause pain and necrosis (deadening of
tissues) at the site of injection.

18. A diabetic patient
making subcutaneous
injection
subcutaneous injection
in the mouse

19. Intramuscular:-
•Injection is made deep into the muscle tissue.
•In humans, the best site is deltoid muscle in the
shoulder or the gluteus muscle in the buttocks.
•This method is suitable for the irritating
substances that cannot be given by subcutaneous
route.
•The speed of absorption from site of injection is
dependent on the vehicle used, absorption is quick
from aqueous solutions and slow from oily
preparations. Absorption is complete, predictable
and faster than subcutaneous route.

20. Intramuscular injection in deltoid and gluteal
muscles

21. Intravenous:-
• Drug solution in injected directly into the
lumen of a vein so that it is diluted in the
venous blood.
• The drug is carried to the Heart and
circulated to the tissues.
• Drugs in oily vehicle or those that cause
haemolysis should not be given by this route.
• Since the drug is introduced directly into
blood, the desired concentration of the drug
is achieved immediately which is not possible
by any other procedure.

22. Intravenous Administration

23. This route is of prime importance in emergency. Also
certain irritant drugs could be given by this route.
Also this is the only route for giving large volume of
drugs e.g. blood transfusion.
However, there are certain disadvantages of this
procedure.
1. Once the drug is injected nothing can be done to
prevent its action.
2. I/v injection requires technical skill to minimize the
risk of leakage of irritant solution into the surrounding
tissues.
3. Air embolism may cause serious problems.

24. Intradermal
• Drug are injected into papillary layer of
skin.
• For example tuberculin injection for
montoux test and BCG vaccination for active
immunization against tuberculosis.
• BCG: Bacille Calmette-Guerin

26. Intradermal Injection

27. Intra Medullary:-
The needle is introduced into marrow cavity and
effects are similar to those following intravenous
injection.
This route is used when veins are not available
specially in children.
In adults the injection is made into marrow cavity
of sternum and under 3 years of age into that of
tibia or femur.

28. Intrathecal:-
• Blood brain barrier often prevents the entry of certain
drugs into the central nervous system.
• e.g. intrathecal injection of streptomycin in tuberculosis
and meningitis used to be used by this route
• The injection of local anaesthetics for the induction of
spinal anaesthesia is given by this route.

29. Intra Cardiac:-
In cardiac arrest intracardiac injection of
adrenaline is made for resuscitation.
Intra-arterial:-
Sometimes a drug is injected directly into
an artery to localize its effects in a particular
tissue or organ. However, the therapeutic value
of such practice is doubtful.

30. INHALATION
Inhalation or Pulmonary Absorption:
• Gaseous and volatile drugs may be inhaled.
• They are then absorbed by pulmonary
endothelium and mucous membrane of the
respiratory tract and reach circulation rapidly.
• Volatile or gaseous anaesthetics such as
halothane, enflurane and nitrous oxide are
administered by this route.

31. • Bronchodilators are generally given from
inhalers in aerosol form.
• Now inhalers have been developed which
allow the supply of accurately metered doses
of drugs.
• This development has greatly extended the
scope of this technique.

32. LOCAL OR TOPIOCAL APPLICATION
Skin
• Drugs applied locally on the skin are poorly
absorbed through the epidermis.
• However, dermis is permeable to many
solutes. Thus systemic absorption of drugs
occurs more readily through abraded,
burned or denuded skin.
• Inflammation and other conditions that
enhance cutaneous blood flow also promote
absorption.

33. • Drugs are applied in the form of ointments,
pastes, poultice and cream to the skin for
their local action.
• However, absorption through skin can be
increased by suspending the drug in an oily
vehicle and rubbing the preparation into the
skin. This method of administration is called
inunction.
Mucous Membranes:-
Drugs are applied onto the various mucous
membranes for their local action.

34. i) Mouth and Pharynx:-
Bitters are used for their reflex action to improve
digestion. Boroglycerine and gentian violet paint (as
astringent) are used for their effects on buccal
mucosa.
ii) Stomach & Intestine:-
Antacids (to neutralize secreted HCl) and emetics
( to induce emesis) are used for their local effect
iii) Rectum:-
Drugs are applied in the form of suppository
or enemas e.g. glycerin suppository for their
local action. Drugs are employed for relief of
itching and pain in haemorrhoid.

35. iv) Respiratory Tract:-
In infections of respiratory tract, tincture
benzoin co steam inhalations give relief from
nasal congestion, phenyl ephrine nasal drops
are also used for nasal congestion.
v) Vagina:-
The drugs are used in the form of pessary or
tablet to treat the vaginal infections. Although
this method can be applied for the drugs that
are absorbed through vaginal mucous
membrane into the circulation, it is restricted
to the local treatment of vaginal conditions

36. vi) Conjunctivae:-
Mydriatics ( to dilate pupil), miotics (to
constrict the pupil), local anaesthetics
antiseptics and antibiotics are applied to the
conjunctivae for their local action.
Conjunctiva: The delicate membrane lining the
eyelids and covering the eye ball.