Routes of drug administration Pharmacology and Toxicology by Devendra Kumar Rawat Assistant professor

1. Pharmacology and Toxicology
By- Devendra kumar Rawat
Assistant Professor
M.Pharm (Pharmacology)
B.M.S. College of Pharmacy, Nasratpur, Tiloi, Distt.-Amethi
(Lecture-2)
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2. Routes of Drug Administration
Most drugs can be administered by a variety of
routes.
The choice of appropriate route in a given situation
depends both on drug as well as patient related
factors.
Routes can be broadly divided into those for
a) Local action
b) Systemic action
 Drugs may be administered by Local or Systemic
routes.
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3. Local Routes
These routes can only be use for localized lesions.
This route is used only for those drugs whose
systemic absorption from these sites is minimal or
absent.
Side effects or toxicity are absent/minimal by this
route.
The local routes are:
1. Topical: This refers to external application of the
drug to the surface for localized action.
 Lotion, Ointment, Cream, Powder, Paints, Drops,
Spray, Suppositories or Pesseries are applied
topically.
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4. Local Routes
2. Deeper tissues: Some drugs are given in deep areas
of tissues by using a syringe and needle but the
systemic absorption is slow.
e.g. Intra-articular injection(Hydrocortisone acetate
in knee joint), Intrathecal injection (Lidocaine),
Retro bulbar injection (Hydrocortisone acetata
behind the eye ball).
3. Arterial supply: Close intra-arterial injection is
used for contrast media in angiography.
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5. Systemic Routes
The drug administered through systemic
routes is intended to be absorbed into the blood
stream and distributed all over, including the site of
action, through circulation.
Systemic routes are as following:
1. Oral or Enteral Route: Oral ingestion is the oldest
and commonest mode of drug administration.
 It is safer, more convenient and painless route.
 Both solid and liquid dosage forms are given orally.
E.g. Tablets, capsules, powders, elixirs, syrups,
emulsions and suspensions.
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6. Systemic Routes
2. Sublingual or buccal: The tablets or
pellet containing drug is placed under the
tongue or crushed in the mouth and spread over the
buccal mucosa.
 Only lipid soluble drugs can be administered by this
route.
 Absorption is very rapid; action can be produced in
minutes. E.g. Nitroglycerin.
3. Rectal: Certain unpleasant drugs can be put into
rectum as suppositories or retention enema for
systemic effect. Absorption is slower.
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7. Systemic Routes
4. Inhalation: Volatile liquids and gases
Are given by inhalation for systemic action, e.g.
general anaesthetics.
 Absorption takes place in alveoli – action is very
rapid.
5. Nasal: The mucous membrane of the nose can
readily absorb many drugs. Desmopressin applied
as a spray or nebulized solution have been used by
this route.
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8. Systemic Routes
6. Parenteral:
(Par – beyond, enteral – intestinal )
 Parenteral refers to administration by injection.
 Parenteral route takes the drug directly into the
tissue fluid or blood.
 Absorption is rapid and quick.
 Drug action is faster and surer.
 It is useful in emergency.
 It is useful in case of an unconscious patient.
 Pain may be produced by injection.
 Self medication is not possible.
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9. Parenteral Routes
A. Subcutaneous (s.c.): The drug is deposited
in the loose subcutaneous tissue which is richly
supplied by nerves.
 Irritant drugs cannot be injected.
 Absorption is slower than i.m.
 Only small volumes can be injected.
B. Intramuscular (i.m.): The drug is injected in one
of the large skeletal muscle – deltoid, triceps,
gluteus maximus, rectus femoris, etc.
 It is less painful.
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10. Different Intramuscular Sites
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11. Parenteral Routes
C. Intravenous (i.v.): The drug is injected as a bolus
or infused slowly over hours in one of the
superficial veins.
 The drug reaches directly into the blood stream and
effect are produced immediately.
 Only aqueous solutions are to be injected.
 Bioavailability is 100%.
D. Intradermal injection: The drug is injected into
the skin raising a bleb (e.g. BCG vaccine).
 This route is employed for specific purpose only.
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