Route of drug administration

The path taken by the drug to get into the
body is known as the route of drug
administration.

Route of drug
administration
Systemic
Enteral Parenteral
Local

the alimentaryEnteral route is through
canal. It might be:
• Oral
• Sublingual
• Rectal

•Oral route is the most common route of drug
administration.
•It may be in the form of tablets, capsules, syrup
emulsions or powders.
e.g. paracetamol tablet for fever, omeprazole capsule for
peptic ulcer are given orally
Advantages:
It is convenient
It is the cheapest available route
Painless
It is safe and acceptable.
Can be self administered

Disadvantages:
•Some of the drug is destroyed by gastric juices
e.g. adrenaline, insulin, oxytocin
•Unabsorbable drugs(e.g. aminoglycosides)
•Unconscious patients
•Patients with severe vomiting and diarrhoea
•Drugs with extensive first pass metabolism
•Unpalatable and highly irritant drugs
First Pass Effect:
•
• First pass effect is the term used for hepatic metabolism
of drug when absorbed and delivered through portal
blood.
Greater the first pass effect, less amounts of the drug
reach the systemic circulation.

Sublingual route involves tablets placed under the tongue or
between cheeks or Gingiva.The drug is absorbed through the
buccal mucous membrane and enters the systemic circulation
directly. The drug should be lipid soluble and small.
Advantages:
•Rapid absorption takes place.
•Drug is dissolved easily
•Drug enters the blood directly
•Spitting out of the drug removes its effect
Disadvantages:.
Irritation of the mucous membrane might occur
Person may swallow the drug
Might be unpleasant in taste.
Examples of drugs given by this route include
nitroglycerin, isoprenaline and oxytocin. Nifedipine used
for the treatment of hypertension in emergency is given by
sublingual route.

Drugs in solid forms such as suppositories or in liquid forms such
as enema are given for systemic effect.
Advantages:
• This route is used when patient having recurrent vomiting or is
unconscious.
• Diazepam solution and paracetamol suppository are rapidly and
dependably absorbed from the rectum in children.
Disadvantages:
• It is inconvenient and embarassing
• Absorption is slower, irregular and often unpredictable
Locally acting drugs include glycerin and Bisacodyl
suppository.

Parenteral route includes: ( based on Site of release)
•
•
•
•
•
•
•
•
•
•
•
Intra muscular
Intra venous
Intra-arterial
Intra-cardiac
Intra-thecal
Intraosseous- into bone marrow
Intrapleural
Intraperitoneal
Intra-articular
Intradermal (Intracutaneous)
Subcutaneous route (Hypodermic)

•Advantages:
• Onset of action of drugs is faster, hence suitable
for emergency
• It is useful for uncooperative patients
• It is useful for unconscious patients
• Inactivation by GIT enzymes is avoided
• First pass effect is avoided
• Bioavailability is 100%
Disadvantages:
• Require aseptic conditions
• Cannot be self administered
• Require invasive techniques, which is painful
• This method is expensive
• Can cause local injury to nerves, vessels etc.

• Subcutaneous route might be used for the arm, forearm,
thigh and subscapular space.
• Insoluble suspensions like insulin, adrenaline applied
by this route.
Advantages:
•
•
Absorption is slow and constant
Self administration is possible
Disadvantages:
•
•
It might lead to abscess formation
Drug absorption is slow, not
suitable for emergency

• Intramuscular route might be applied to the deltoid,
gluteus maximus and vastus lateralis.
• A volume of 5-10ml can be given at a time
Advantages:
•Absorption is rapid as compared to oral route
•Oily preparations, mild irritants, depot injections,
soluble substances and suspensions can be
given by this route.
Disadvantages:
• Using this route might cause nerve or vein damage.

• Intravenous injections might be applied to the cubital,
basilic and cephalic veins.
Advantages:
•
•
•
•
•
•
•
•
•
Immediate action takes place
This route is preferred in emergency situations
This route is preferred for unconscious patients.
Titration of dose is possible.
Large volume of fluids might be injected by this route
Diluted irritant might be injected
Absorption is not required
No first pass effect takes place.
Blood plasma or fluids might be injected.

• Once the drug is injected, its action can’t be halted
• Local irritation may cause phlebitis
• Self-medication is usually not possible
• Strict aseptic conditions are needed
• Infiltration of surrounding tissues might result.
• This method is not suitable for oily preparation
• Extravasation of some drug may cause injury,
necrosis and sloughing of tissues

d. Intradermal injections:
• This route is mostly used for diagnostic
purposes and is involved in:
Schick test for Diphtheria
Vaccines include DBT and BCG
Sensitivity to penicillin vaccine
Sensivity test like tuberculin and
allergy test

e. Intraarterial route:
• This method is used for chemotherapy in cases
of malignant tumors and in angiography.
f. Intracardiac route:
• Injection can be applied to the left ventricle in
case of cardiac arrest.
g. Intrathecal route:
• Intrathecal route involves the subarachnoid
space. Injection may be applied for the lumbar
puncture, for spinal anesthesia and for
diagnostic purposes. This technique requires
special precautions.

h. Intra-articular route:
• Intra-articular route involves injection into the joint cavity.
Corticosteroids may be injected by this route in acute
arthritis.
example: hydrocortisone in rheumatoid arthritis
i. Intraperitoneal route:
• Intraperitoneal route may be used for peritoneal dialysis.
j. Intrapleural route:
• Penicillin may be injected in cases of lung empysema
by intrapleural route.
k. Injection into bone marrow
• This route may be used for diagnostic or therapeutic
purposes.

 Rapid absorption
 Rapid onset of action
 This route has minimum side effects.
 Effective for patients with respiratory problems
 Fewer systemic side effects
 Effective and convenient for patients with respiratory disorders
3. Inhalation
Inhalation routes provide rapid delivery of a drug across the
large surface area of the mucous membranes of the
respiratory tract and pulmonary epithelium.
Advantages:
Disadvantages:
•Most addictive route (drug can enter the brain quickly)
•Irritation of the respiratory tract may take place.
•It require training

Topical administration is the application of a drug
directly to the surface of the skin
Includes administration of drugs to any mucous
membrane
eye
nose
ears
lungs

 Advantages and Disadvantages of the
Topical Route
Local therapeutic effects
Not well absorbed into the deeper layers of the
skin or mucous membrane
lower risk of side effects
Transdermal route offers steady level of drug
in the system
sprays for inhalation through the nose may be
for local or systemic effects

Route of drug administration

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