Department of Pharmacology & Toxicology
College of Veterinary Science & Animal Husbandry
NAU Campus
Kamdhenu University
ROUTES OF DRUG ADMINISTRATION
Systemic routes
Oral
Parenteral
Inhalation
Local route
Topical
FACTORS GOVERNING THE CHOICE OF
ROUTE OF DRUG ADMINISTRATION
Physicochemical properties of the drug
Site of desired action of drug: Localized or
generalized
Rate and extent of absorption of the drug from
different routes
Effect of digestive juices, ruminal microflora and
first pass metabolism on the drug
FACTORS…
Rapidity with which the response is desired (routine
treatment / emergency)
Intensity of action desired
Type of response required
Accuracy of dosage required
Condition of the patient (unconscious, vomiting etc.)
ORAL / ENTERAL ADMINISTRATION
Advantages:
Safe and convenient
Drug preparation need not to be sterile
Both liquid and solid dosage forms can be given orally
Most suitable route for gastrointestinal tract infection
and GI parasites
Large volume of liquid drug preparation can be
administered
ORAL ROUTE…
Disadvantages:
Slower onset of action, so not suitable for emergency
situations
Drug absorption is irregular and unpredictable and
affected by ingesta and other GI disturbances.
Not suitable for uncooperative, unconscious or vomiting
patients. It is also not suitable for fractious, wild and zoo
animals.
It is not much useful in ruminants because presence of
large amount of ingesta in rumen decreases absorption of
drugs.
ORAL ROUTE…
Strong electrolyte and highly polar drugs are not absorbed
by oral route as they remain largely ionized in GI tract.
Poor administration technique may cause aspiratory
bronchopneumonia.
Not suitable for drugs which undergoes extensive
intestinal or hepatic first pass effect (metabolism during
the first passage through intestine or liver)
Chance of super infection: oral therapy with antimicrobial
suppresses the beneficial effects of ruminal and intestinal
microflora (inhibition of vitamin synthesis)
INTRAVENOUS ROUTE (IV)
Advantages:
Quick onset of action, so useful in emergency situations
Provide 100% bioavailability
Highly irritating and non-isotonic solutions can be given
by slow IV injection (because endothelium of blood vessel
does not contain nerve supply)
Large volume of fluids can be administered
Useful when precise control of the drug effect is required
Drugs that are rapidly metabolized can be infused slowly
over time
INTRAVENOUS ROUTE (IV)
Disadvantages:
It require special skill and technique
Extravasation of irritant drugs may cause phlebitis
(inflammation of vein) and necrosis of adjoining tissues
One of the least safe methods of drug administration because
vital tissues like heart, brain, kidneys may be affected. Over
dosage can lead to immediate toxicity.
Injection/ inoculum must be perfectly sterile, pure and soluble
Not suitable for insoluble drugs, oil substances or drugs in
suspension
It provide short duration of action
INTRAVENOUS ROUTE (IV)
INTRAMUSCULAR ROUTE (IM)
Advantages:
This route can be used for solutions, aqueous and oily
suspension and other depot preparation
Absorption is fairly rapid except for oily and depot
preparation
Mild to moderate irritant preparations can be injected but
are not generally advised
The duration of action is longer than IV route but usually
shorter than for SC administration.
Most suitable route for fractious, wild and zoo animals,
which may be difficult to restraint
INTRAMUSCULAR ROUTE (IM)
Disadvantages:
Large volume of fluids cannot be injected.
Possibility of improper deposition of drugs in
nerves, blood vessels, fat or connective tissues
Not suitable for emergency situation
SUBCUTANEOUS ROUTE (SC)
Advantages:
Large volume of nonirritant drug can be administered
Absorption of drugs is rapid, but slower than from IM
site
Suitable for pellet implantation and depot
preparation
Rate of absorption can be manipulated by application
of heat (increase) or cold (decrease)
SUBCUTANEOUS ROUTE (SC)
Disadvantages:
Not suitable for irritant drugs
It is not suitable in shock states because reduced
peripheral circulation may markedly decrease the
absorption rate.
INTRAPERITONEAL ROUTE (IP)
Advantages:
It provides fairly rapid absorption of drugs
Large volume of drugs may be administered
It is suitable for small size animals (e.g. rodents)
Disadvantages:
It is not suitable for irritating compounds because
they may induce peritonitis.
There is possibility of puncturing the intestine and
other abdominal organs
INTRAPERITONEAL ROUTE (IP)
INTRATHECAL ROUTE:
In intrathecal (intraspinal,
subarachnoidal)
administration, the drug is
deposited into the
subarachnoid space
EPIDURAL ROUTE:
Drug is deposited through a vertebral interspace into
the epidural space.
Needle does not penetrate in meninges and thus less
risk of traumatic injury.
Preferable site of injection is between first and
second coccygeal vertebrates in horse and cattle.
Other site for epidural route is sacro-coccygeal space.
EPIDURAL ROUTE:
OTHER ROUTES
Other routes Injection site
Intra-arterial route Artery
Intra-cardiac route Heart muscle
Intra-tracheal route Between rings of trachea
Intra-medullary route Bone marrow (medullary cavity) (used in
neonates)
Intradermal OR Within layers of skin (dermis)
Intra-cutaneous route
Intra-articular route Joint space
Intra-ruminal route Directly into rumen through hollow of flank
Intra-thoracic route OR Pulmonary space
Intra-pulmonary route
INHALATION / PULMONARY ROUTE
Advantages:
Alveoli offer vast surface for drug absorption. This facilitate
rapid onset of systemic effects for volatile liquids and gases.
Controlled administration of drug is possible for moment to
moment adjustment.
It avoids drug loss though hepatic and intestinal first pass
effect.
Suitable for respiratory tract disease
Disadvantages:
Require special technique, device and skill to operate.
Not suitable for irritant substances
Non convenient route for domestic animals
INHALATION / PULMONARY ROUTE
TOPICAL ADMINISTRATION/ LOCAL
APPLICATION
Skin:
Bath: Immersion of body in medicated water
Dip: It is a type of bath in which whole body is immersed for
a time in medicated fluid particularly insecticidal fluid. In
veterinary medicine, dips are generally used in small
animals to kill ectoparasites.
Inunction: Application of semisolid to liquid drug
preparation on the surface of body with smearing or
rubbing. E.g. ointments, liniments etc.
Dusting: Application of fine particles of solid matter on the
surface of body.
Mucous Membranes:
Topical application of drugs on mucous membranes is used for
local action.
Sublingual and buccal route: Used for highly lipid soluble and non-
irritating drugs. The drug avoids hepatic and intestinal first pass
effects.
Rectal/ Per rectal route: Used for insertion of drugs in rectum. E.g.
rectal suppository or Enema
Intra-ocular: Eye
Intra-nasal: Nose
Intra-mammary: Teats of mammary gland
Intra-uterine: In uterus
Intra-vaginal: In vagina
Aural: Ear
SPECIALIZED DRUG DELIVERY SYSTEMS
Transdermal Delivery System (TDS)
TDS are topically administered drug in form of
adhesive patches that deliver the contained drugs at
a predetermined and controlled rate into systemic
circulation via stratum corneum.
The TDS bypasses first pass effect and is considered
useful for drugs having either very short half-lives
or narrow therapeutic indices.
Liposomes (Lipid Bodies)
They are minute (25-5000 nm) of lipid bilayers enclosing an
aqueous compartment.
Water soluble drugs are enclosed in the aqueous compartment
while lipophilic drugs are incorporated in the lipid phase of the
liposomes.
After parenteral administration, the liposomal carrier systems
deliver the drug across cell membranes (e.g. by phagocytosis) not
normally permeable to free form.
Dermojet/ Hypospray
It is a special form of subcutaneous administration in which
needle is not used.
In this method, a high velocity jet of drug solution is projected
from a micro fine orifice using a gun like device.
Dermojet/ Hypospray
Thank You
