2. ROUTES OF DRUG
ADMINISTRATION
o Refers to a path by which a drug, fluid or
other substance is taken into the body.
o The route of administration of a drug is
determined by the physical and chemical
properties of the drug, patient
characteristics, and the rapidity of
response desired. 2
4. 1. ENTERAL ROUTE OF
ADMINISTRATION
o Administration through the GIT.
o Includes Oral, rectal, sublingual, sublabial
4
5. ORAL ROUTE
o Is the safest, most economical and the
most convenient way of giving medicines.
o The dosage forms for oral route include
tablets, capsules, powders, mixtures,
syrups, and gels.
o Drugs in solution are absorbed faster
than in solid form.
5
6. ORAL ROUTE
o For rapid effect drug should be diluted
and given with water before meals, also
get faster absorption on an empty
stomach.
o If a drug is likely to cause gastric
irritation it is given with or immediately
after meals.
o If a medication such as syrup is given for
local effect on the throat it should not be
6
7. ORAL ROUTE
Disadvantages
o Has slower on set, and more prolonged,
but less potent-effect due to:
o gastric or intestinal pH (drug ionisation)
o gastric motility (contact time)
o variation in absorption due to food content
or pathology within the gut
o alteration of the drug due to its
inactivation or partial destruction by the
liver enzymes
7
8. ORAL ROUTE/DISADVANTAGES
o An objectionable odour or taste
which can affect compliance.
o Irritation of the gastric mucosa,
causing nausea and vomiting.
o Aspiration into the lungs
8
9. OTHER ENTERAL ROUTES
o Nasogastric or gastrostomy tubes – tubes placed
in gastro-intestinal tract in patients who cannot
swallow.
o Sublingual – drugs such as nitro glycerin (for
angina), are placed under the tongue and retained
until dissolved and absorbed or desired effect is
produced.
The rich capillary network and thin epithelium
under the tongue permits rapid absorption and
therefore quick drug action.
In addition drug is saved from hepatic inactivation
9
10. RECTAL
Used when stomach is non-receptive due to:
• vomiting,
• when drug has an objectionable taste or
odour, or
• can be destroyed by digestive enzymes or
• when patient is unconscious
• When drug is meant for local use in the
rectum.
Drugs like paracetamol, aminophylline, may be
administered rectally.
10
11. 2. PARENTERAL ROUTES
Parenteral route is used to give
injections:
• Intradermally
• Subcutaneously (SC)
• Intramuscularly (IM)
• Intravenously (IV)
11
12. PARENTERAL ROUTES
These routes are selected if the drug is;
• Poorly absorbed from the gut
• Inactivated by digestive enzymes
• Metabolized by liver enzymes
• Patient is unable to take or tolerate oral
medication
• Rapid effect is desired
• No other dosage form is available.
12
13. PARENTERAL ROUTES
o Aseptic technique must be employed when
the injection is given parenterally.
o Poor technique may cause infection at the
site of injection or systemic infection or
cause embolism.
13
14. PARENTERAL ROUTES
I. Intradermal Injection
o Drug injected in outer layer of the skin
(intracutaneous).
o Amount of drug given is small and absorption
slow. The medial (inside) forearm is usually used.
o Mostly used for diagnostic tests such as Schick
test for Diptheria also used for BCG vaccine.
14
15. PARENTERAL ROUTES
II. Subcutaneous Injection (SC)
o Injection is made into the loose subcutaneous
tissue under the skin.
o Common sites are outer surface of the fore
arm, abdomen and front of the thigh.
o Used for small amounts of drug (2ml or less),
absorption is slow but drug action lasts
longer.
e. g Used for administration of Insulin and
Morphine.
15
16. PARENTERAL ROUTES
III. Intramuscular Injection (IM)
o Needle penetrates the subcutaneous tissue, the
drug is deposited deep between layers of muscle.
o Suitable for administering solutions or
suspensions.
o The muscle is more vascular and less sensitive
than subcutaneous tissue therefore gives better
16
17. PARENTERAL ROUTES
… IM
o Oils or waxes along with drug to delay
absorption and prolonged action are used.
o IM is used for long acting esters such as sex
hormones, corticosteroids, or poorly soluble
salts such as Benzathine penicillin G or Procaine
Penicillin.
17
18. PARENTERAL ROUTES
IV. Intravenous Injection (IV)
o The drug is introduced directly into a
vein as an injection or by infusion.
o Used when an immediate effect is
desired or
o When for any reason the drug cannot be
injected into other tissues or
o When absorption can be inhibited by
poor circulation.
18
19. … IV
o The vein at the bend of the elbow is selected
although any other suitable site can be used.
o The dose has to be accurate because drug
directly reaches the blood stream.
o Small amounts of solution are given as a bolus
but slowly.
o Insoluble drugs, oily substances, or drugs in
suspension, markedly acid or alkaline salts
should never be given by IV route.
19
20. An Infusion
Is the intravenous administration of larger
amounts of fluid, varying from 200 ml to 2 litres.
Fluid flows by gravity from a graduated container
through an IV giving set. This gives a slow
administration of fluid into the body at a uniform
rate.
Used to relieve tissue dehydration, to restore
depleted blood volume etc.
20
21. PARENTERAL/IV
Limitations
o Drug is excreted rapidly, therefore duration
of action is short.
o Overdose can lead to immediate toxicity
o Leakage into surrounding tissue may cause
tissue damage.
o Special aseptic skill precautions are required.
o Accidents such as embolism or veno-
thrombosis may occur.
21
22. PARENTERAL ROUTES
V. Intramedullary injection
o This route is also called bone marrow
injection.
o The drug is injected in the bone marrow of the
sternum or tibia.
o Used when veins not available, whole blood,
normal saline, or glucose can be given this
22
23. PARENTERAL ROUTES
VI. Intra-arterial injection
o Needle is placed in artery, used for
drawing blood sample for blood gas
studies.
o Certain cytotoxic drugs may be perfused
this way to localise effect.
23
24. PARENTERAL ROUTES
VII.Intrathecal (Intraspinal) injection
o The drug is injected into the subarachnoid
space, into the spinal fluid, usually by
lumbar puncture.
o Is a specialized technique fraught with
danger of accidental puncturing of a nerve
fibre.
o Used in treating menengitis, and giving
spinal anaesthesia. 24
25. PARENTERAL ROUTES
VIII. Epidural injection
o Drug is deposited through a
vertebral interspace, used to
produce epidural nerve block by
depositing a local anaesthetic.
25
27. PARENTERAL ROUTES
X. Intra-articular injection
o The drug (usually a glucocorticoid) is
injected into the joint space to attain
high local concentration within the
inflammed joint without much danger
of systemic steroid toxicity.
27
28. PARENTERAL ROUTES
XI. Intraperitoneal injection
o Needle is inserted into the peritoneal
space, and special fluid circulated through
the space to remove toxins or drugs in
cases of poisoning.
o Route most used in peritoneal dialysis.
28
29. 3. DERMAL APPLICATION
o There are 3 principal targets for topical drug
delivery;
the skin surface
the skin itself (epidermis or dermis) or
the systemic circulation
o The dosage forms applied topically to the
skin are: powders, lotions, liniments,
ointments, creams, pastes, and gels.
29
30. DERMAL APPLICATION
o These preparations are used mostly for their
local antiseptic, antipruritic, analgesic,
emollient and healing effects.
o Absorption of drugs through the skin is
proportional to their lipid solubility, because
the epidermis acts like a lipid membrane
barrier.
30
31. DERMAL APPLICATION
DRUG PENETRATION PATHWAYS
There are critically 3 ways in which a drug
molecule can cross the intact stratum
corneum:
• skin appendages (shunt routes)
• by a transcellular route
• through the intercellular lipid domains
A particular drug is likely to permeate by a
combination of these routes 31
32. DERMAL
APPLICATION/ADVANTAGES
o Facilitates sustained delivery of drug, achieving a steady-
state profile. This reduces the likelihood of peak-
associated side effects, and ensures that drug levels are
above the minimal therapeutic concentration.
o Avoids 1st pass metabolism
o Ease of use negates the need for specialised healthcare
staff to administer drugs, potentially reducing treatments
costs.
o Dosage form can be easily removed in the event of
32
33. DERMAL
APPLICATION/LIMITATIONS
o Owing to the excellent barrier properties of the skin,
permeated amounts tend to be low. Therefore, only
potent drugs are applicable to this administration
route
o Skin irritation. Drugs and excipients may cause
sensitisation, reactions such as erythema and oedema
o Patches tend to be relatively complex systems, which
are expensive to develop and manufacture
33
34. DERMAL APPLICATION
To do
The difference between topical and
transdermal drug delivery.
Strategies for enhancing drug penetration
through the skin.
Maximum 2 pages
34
35. OTHER ROUTES
Vaginal
Used mostly for:
Treating local infections.
Obstetrics
Dosage forms used:
Pessaries
Douches
Creams and Gels
35
36. OTHER ROUTES
Nasal
Mostly used for:
Local effect in the nose.
Effect on the respiratory tract.
Anaesthetic administration
Oxygen administration
Avails rapid onset of action due to high capillary
vascularity.
36
37. OTHER ROUTES/NASAL
Prevents drug from systemic degradation.
Difficult to administer exact dose.
The route is used to administer:
Volatile products such as:
Gaseous anaesthetics
Vapours
Oxgen
Non-volatile products such as:
Powders, liquids
37
38. OTHER ROUTES/NASAL
Devices used include:
Anaesthetic and oxygen masks.
Vapourisers
Atomizers
Nebulizers
Inhalers
Spinhalers.
38
39. OTHER ROUTES
Eye and Ear
Used for local drug effect.
Avails rapid onset of action.
Protects drug from degradation.
Dosage forms used:
Drops
Ointment
Washes
Oils
39
40. TEXTBOOKS
o Basic and Clinical pharmacology 10th
Edition, B. G. Katzung
o Intergrated Pharmacology 3rd Edition,
Page et al
o Rang and Dale’s Pharmacology 8th
edition
40
