Drugs can be administered through various routes including oral, injection, inhalation, rectal, topical, and others. The choice of route depends on factors like the drug's properties, the desired site of action, rate of absorption, and patient condition. Oral administration is the most common due to convenience, but other routes like injection allow for more rapid onset when needed. Each route has advantages and disadvantages related to factors like onset of action, bioavailability, risk of side effects, and patient acceptability.

1. Route of Drug Administration
By Abubakar salisu fago.

2. Drugs are introduced into the body by several routes. They
may be taken by mouth (orally); given by injection into a vein
(intravenously), into a muscle (intramuscularly), into the
space around the spinal cord (intrathecally), or beneath the
skin (subcutaneously); placed under the tongue
(sublingually); inserted in the rectum (rectally) or vagina
(vaginally); instilled in the eye (by the ocular route); sprayed
into the nose and absorbed through the nasal membranes
(nasally); breathed into the lungs, usually through the mouth
(by inhalation); applied to the skin (cutaneously) for a local
(topical) or bodywide (systemic) effect; or delivered through
the skin by a patch (transdermally) for a systemic effect. Each
route has specific purposes, advantages, and disadvantage

3. Most of the drugs can be given through number of routes.
Choice of proper route is depend on factors which are related to patient and
drugs as well.
Important factors which govern the choice of route of drug administration are
a. Physical and chemical properties of drugs ( solid/liquide/gas/stability/PH /
irritancy
b. Site of desire action- localized and approachable and generalized and
nonapproacheable
c. Rate and extent of drug absorption
d. Effect of digestive juice and first pass metabolism of drugs
e. Rapidity at which response is desired
f. Accuracy of dose required
g. Condition of patients

4. Grossly we can divide into those for
a. Local action
b. Systemic action
Local routes of drug administration
a. Topical
b. Dipper tissue
c. Arterial
Systemic routes
Oral
Sublingual (S.I) or buccal
Rectal
Cutaneous
Inhalation
Nasal
Parenteral
a. Subcutaneous (S.C) – Dermojet, Pellet
Implantation, Sialistic (nonbiodegradable)
and biodegradable
b. I.M
c. I.V
d. Intradermal injection

5. Local route s
These route can be use for localized lesions at accesible
sites and drugs whose systemic absorption is minimal
or absents. Thus higher concentration is attained at the
site of desire without exposing the rest of the body.
Topical:
Refers to external application of the drug to the surface
of the body for their localized action. It is more
encouraging and often convenient.
Drugs can be efficiently delivered to the localized lesion
on the skin, eye, ears, nose, oropharyngeal /nasal
mucus, rectum , vagina in the form of
powder, lotion, ointment, cream, suspension, emulsion,
suppositories, logenzegs.
Non-absorbable drug can be given orally into the GI
mucosa eg. Sucralfalte or Vancomycine .

6. Deeper tissue:
Certain deep area can be approach through syringe and
needle but drug should be such that systemic absorption
is slow.
Eg. Intra-articular injection (hydrocortisone) or intrathecal
injection ( hydrocortisone)

7. Intra-Arterial route- Close intra-arterial injection
used for contrast media in angiography
Anti-cancer drug can be infused in femoral or brachial
artery to localized the effect for lower limb
malignancy.

8. Intra-arterial route (IA)
The parenteral formulation is injected into an
accessible artery.
This route requires specialist training to administer
therapeutic agents as if the artery is missed, possible
damage to adjacent nerves may result.
The IA route is used to administer radiopaque media
to visualize organs, e.g. heart, kidney.

9. Intradural and extradural routes
Intradural and extradural administration is
employed to achieve spinal anaesthesia.
 Intradural administration involves injection of the
therapeutic agent within the dural membrane
surrounding the spinal cord.
 Extradural administration involves injection of the
therapeutic agent outside the dural membrane and
within the spinal caudal canals

11. Systemic Routes
Oral
Oldest and common mode of drug
administration
 Safer and more convenient and does
not need any assistance
 Noninvasive and often painless
 Product need not to be sterile so drugs
is cheaper
 Both solid and liquid dosage form can
be administer

12. Oral route of drug administration
What is First pass metabolism?
First pass effect

13. Oral Route of drug administration
Limitations
Action is slow thus not suitable for emergency
 Unpalatable drugs are difficult to administer
(Chloramphenicol) drug may be circumvent with capsule
 May causes nausea and vomiting
 Can not be used for noncooperative patients/
Unconscious and vomitous patients
 Absorption of drug is variable
 Others are destroyed the drug with digestive juice
(pen) or in liver (GTN, testosterone, lidocaine)

14. Sublingual or Buccal
The tablet or pellet containing drugs placed under the tongue or
crushed in mouth and spread over the buccal mucosa.
Only lipid soluble non-irritating drugs can be give in this route.
Absorption is relatively rapid-action can be produce in a minutes
Though it is inconvenient one can spit the drug once the desired
action of drug obtained.
The cheap advantages is liver is by passed thus drugs are protected
from fast pass metabolism and drugs are directly into the systemic
circulation.
Eg. GTN, desamino oxytocin.

15. Rectal:
Certain irritating and unpleasant drug can
be given through rectal route in the form of
suppositories or retention enema for their
systemic effects.
•It is rather inconvenient and
embracing, absorption is slower, irregular
and often unpredictable.
•Drug absorbed through external
haemorrhoidal (50% by passed) and
internal haemorrhoidal veins.
Rectal inflammation and leaking can occur.
eg.Diazepam, Indomethacine, paraldehyde.

16. Vaginal Route: Some drugs may be administered
vaginally to women as a
solution, tablet, cream, gel, suppository, or ring. The
drug is slowly absorbed through the vaginal wall. This
route is often used to give estrogen to women at
menopause, because the drug helps prevent thinning
of the vaginal wall, an effect of menopause (see
Menopause: Hormone Therapy).

17. Cutaneous:
Highly lipid soluble drug can be applied over the skin for
slow, constant and prolong absorption. Drugs usually in
the form of ointment , cream, or in the form of specially
designed device like transdermal drug delivery system are
given in this route.
> The drug should be highly lipid soluble and non-irritant
in nature.
> Liver is by passed.
>Absorption can be enhanced by rubbing the drugs over
the skin.
>Transdermal drug delivery system:

18. Inhalation:
Volatile liquid and gases are given in this route
for their systemic actions. Eg. General anesthesia.
 Absorption take place from the vast surface of
alveoli- action is very rapid.
 When administration is discontinued the drug is
defused back into the exhaled air and eliminate
and action slowly subside.
 Thus control administration is possible in
moment to moment by adjustment.
 Irritant vapor cause inflammation to respiratory
tract and cause excessive secretion
and may choke the air way.

20. Nasal Route: If a drug is to be breathed in and
absorbed through the thin mucous membrane that
lines the nasal passages, it must be transformed into
tiny droplets in air (atomized). Once absorbed, the
drug enters the bloodstream. Drugs administered by
this route generally work quickly. Some of them
irritate the nasal passages. Drugs that can be
administered by the nasal route include nicotine
(for smoking cessation), calcitonin (for
osteoporosis), sumatriptan (for migraine
headaches), and corticosteroids (for
allergies).

21. Parentral route of drug administration

23. Subcutaneous (S.C)
The drug is deposited into the loose subcutaneous tissue
which is richly supplied by nerves (irritant drug can not be
injected) but less vascular ( absorption is slower). Only
small volume of drug can be injected through this route.
Self injection is possible because deep penetration is not
needed.
The route should be avoided to shock patient who are
vasoconstricted.
Some special forms of these routes
a. Dermojet
b. Pellet implantation
c. Sialistic and biodegradable implants

24. Dermojet:
In this method needle is not
needed, a high velocity jet of
solution is projected from the
micro fine orifice of a gun like
implements. The solution is
cross the superficial layer and
deposited into the
subcutaneous tissue. It is
usually painless.

25. Pellet Implantation:
Drug in the form of solid pellet is introduce under the skin with a trocher and cannula. This
provides sustained release of drugs over weeks together to few months.
Eg. DOCA and testosterone.

26. A- Intravascular (IV, IA):
- placing a drug directly into blood stream.
-May be - Intravenous (into a vein) or - intraarterial (into an
artery).
Advantages
1- precise, accurate and immediate onset of action, 100%
bioavailability.
Disadvantages
1- risk of embolism.
2- high concentrations attained rapidly leading to greater risk
of adverse effects

27. B-Intramuscular :(into the skeletal muscle).
Advantages
1- suitable for injection of drug in aqueous solution
(rapid action) and drug in suspension or emulsion
(sustained release).
Disadvantages
1- Pain at injection sites for certain drugs.